AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/10/15 11:30	flow	patch-triage	1m Args: null Results: { "EnableConfigs": null, "FocusSymbols": [], "KMSANReasoning": "", "NeedsKMSAN": false, "Reasoning": "All modified functions (including fdt_scan_reserved_mem, __reserved_mem_init_reg, __reserved_mem_reserve_reg, __rmem_check_for_overlap, and unflatten_device_tree) are marked __init and execute strictly during early boot. Their memory is reclaimed at free_initmem() before user space initializes, making them unreachable by syzkaller. Furthermore, early device tree reserved memory scanning (fdt_scan_reserved_mem via early_init_fdt_scan_reserved_mem) is exclusive to architectures such as ARM, ARM64, PowerPC, and RISC-V, and is not called on the target architecture (amd64).", "WorthFuzzing": false }
1/1	2026/10/15 11:30	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit fbb3cd8c7b1055d78ff134cad6158f7bca85efee\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Thu Oct 15 11:30:41 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/drivers/of/fdt.c b/drivers/of/fdt.c\nindex ecc9231026224..a58efdcbac7f1 100644\n--- a/drivers/of/fdt.c\n+++ b/drivers/of/fdt.c\n@@ -1283,9 +1283,6 @@ void __init unflatten_device_tree(void)\n {\n \tvoid fdt = initial_boot_params;\n \n-\t/ Save the statically-placed regions in the reserved_mem array /\n-\tfdt_scan_reserved_mem_late();\n-\n \t/ Populate an empty root node when bootloader doesn't provide one /\n \tif (!fdt) {\n \t\tfdt = (void ) __dtb_empty_root_begin;\ndiff --git a/drivers/of/of_private.h b/drivers/of/of_private.h\nindex 0ae16da066e2c..895f868b4cfa1 100644\n--- a/drivers/of/of_private.h\n+++ b/drivers/of/of_private.h\n@@ -9,7 +9,6 @@\n /\n \n #define FDT_ALIGN_SIZE 8\n-#define MAX_RESERVED_REGIONS 64\n \n /\n struct alias_prop - Alias property in 'aliases' node\n@@ -186,7 +185,6 @@ static inline struct device_node __of_get_dma_parent(const struct device_node \n #endif\n \n int fdt_scan_reserved_mem(void);\n-void __init fdt_scan_reserved_mem_late(void);\n \n bool of_fdt_device_is_available(const void blob, unsigned long node);\n \ndiff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c\nindex 8c9d6395d6a39..0fd1683cba011 100644\n--- a/drivers/of/of_reserved_mem.c\n+++ b/drivers/of/of_reserved_mem.c\n@@ -27,10 +27,10 @@\n \n #include \"of_private.h\"\n \n-static struct reserved_mem reserved_mem_array[MAX_RESERVED_REGIONS] __initdata;\n-static struct reserved_mem reserved_mem __refdata = reserved_mem_array;\n-static int total_reserved_mem_cnt = MAX_RESERVED_REGIONS;\n+static struct reserved_mem reserved_mem __refdata;\n+static int total_reserved_mem_cnt;\n static int reserved_mem_count;\n+static bool reserved_mem_reserve_failed __initdata;\n \n static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,\n \tphys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,\n@@ -59,57 +59,28 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,\n }\n \n /\n- * alloc_reserved_mem_array() - allocate memory for the reserved_mem\n- * array using memblock\n- \n- This function is used to allocate memory for the reserved_mem\n- * array according to the total number of reserved memory regions\n- * defined in the DT.\n- * After the new array is allocated, the information stored in\n- * the initial static array is copied over to this new array and\n- * the new array is used from this point on.\n+ * On some architectures (e.g. ARM64) the linear mapping is not yet usable\n+ * during the early reserved memory scan, so the array has to be accessed\n+ * through a temporary early mapping. PPC64 runs the scan before early_ioremap\n+ * is initialized, but the memory returned by memblock is already accessible.\n /\n-static int __init alloc_reserved_mem_array(void)\n+#if defined(CONFIG_GENERIC_EARLY_IOREMAP) \u0026\u0026 !defined(CONFIG_PPC64)\n+#include \u003casm/early_ioremap.h\u003e\n+static inline void early_array_map(void array, size_t size)\n {\n-\tstruct reserved_mem new_array;\n-\tsize_t alloc_size, copy_size, memset_size;\n-\tint ret;\n-\n-\tif (!total_reserved_mem_cnt)\n-\t\treturn 0;\n-\n-\talloc_size = array_size(total_reserved_mem_cnt, sizeof(new_array));\n-\tif (alloc_size == SIZE_MAX) {\n-\t\tret = -EOVERFLOW;\n-\t\tgoto fail;\n-\t}\n-\n-\tnew_array = memblock_alloc(alloc_size, SMP_CACHE_BYTES);\n-\tif (!new_array) {\n-\t\tret = -ENOMEM;\n-\t\tgoto fail;\n-\t}\n-\n-\tcopy_size = array_size(reserved_mem_count, sizeof(new_array));\n-\tif (copy_size == SIZE_MAX) {\n-\t\tmemblock_free(new_array, alloc_size);\n-\t\tret = -EOVERFLOW;\n-\t\tgoto fail;\n-\t}\n-\n-\tmemset_size = alloc_size - copy_size;\n-\n-\tmemcpy(new_array, reserved_mem, copy_size);\n-\tmemset(new_array + reserved_mem_count, 0, memset_size);\n-\n-\treserved_mem = new_array;\n-\treturn 0;\n-\n-fail:\n-\tpr_err(\"Failed to allocate memory for reserved_mem array with err: %d\", ret);\n-\treserved_mem_count = 0;\n-\treturn ret;\n+\treturn early_memremap(__pa(array), size);\n+}\n+static inline void early_array_unmap(void map, size_t size)\n+{\n+\tearly_memunmap(map, size);\n+}\n+#else\n+static inline void early_array_map(void array, size_t size)\n+{\n+\treturn array;\n }\n+static inline void early_array_unmap(void map, size_t size) {}\n+#endif\n \n static void fdt_init_reserved_mem_node(unsigned long node, const char uname,\n \t\t\t\t phys_addr_t base, phys_addr_t size);\n@@ -174,222 +145,39 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,\n \t} else {\n \t\tpr_err(\"Reserved memory: failed to reserve memory for node '%s': base %pa, size %lu MiB\\n\",\n \t\t uname, \u0026base, (unsigned long)(size / SZ_1M));\n+\t\treserved_mem_reserve_failed = true;\n \t}\n \treturn 0;\n }\n \n /\n- * __reserved_mem_check_root() - check if #size-cells, #address-cells provided\n- * in /reserved-memory matches the values supported by the current implementation,\n- * also check if ranges property has been provided\n- /\n-static int __init __reserved_mem_check_root(unsigned long node)\n-{\n-\tconst __be32 prop;\n-\n-\tprop = of_get_flat_dt_prop(node, \"#size-cells\", NULL);\n-\tif (!prop \|\| be32_to_cpup(prop) != dt_root_size_cells)\n-\t\treturn -EINVAL;\n-\n-\tprop = of_get_flat_dt_prop(node, \"#address-cells\", NULL);\n-\tif (!prop \|\| be32_to_cpup(prop) != dt_root_addr_cells)\n-\t\treturn -EINVAL;\n-\n-\tprop = of_get_flat_dt_prop(node, \"ranges\", NULL);\n-\tif (!prop)\n-\t\treturn -EINVAL;\n-\treturn 0;\n-}\n-\n-static int __init __rmem_cmp(const void a, const void b)\n-{\n-\tconst struct reserved_mem ra = a, rb = b;\n-\n-\tif (ra-\u003ebase \u003c rb-\u003ebase)\n-\t\treturn -1;\n-\n-\tif (ra-\u003ebase \u003e rb-\u003ebase)\n-\t\treturn 1;\n-\n-\t/\n-\t Put the dynamic allocations (address == 0, size == 0) before static\n-\t * allocations at address 0x0 so that overlap detection works\n-\t * correctly.\n-\t /\n-\tif (ra-\u003esize \u003c rb-\u003esize)\n-\t\treturn -1;\n-\tif (ra-\u003esize \u003e rb-\u003esize)\n-\t\treturn 1;\n-\n-\treturn 0;\n-}\n-\n-static void __init __rmem_check_for_overlap(void)\n-{\n-\tint i;\n-\n-\tif (reserved_mem_count \u003c 2)\n-\t\treturn;\n-\n-\tsort(reserved_mem, reserved_mem_count, sizeof(reserved_mem[0]),\n-\t __rmem_cmp, NULL);\n-\tfor (i = 0; i \u003c reserved_mem_count - 1; i++) {\n-\t\tstruct reserved_mem this, next;\n-\n-\t\tthis = \u0026reserved_mem[i];\n-\t\tnext = \u0026reserved_mem[i + 1];\n-\n-\t\tif (this-\u003ebase + this-\u003esize \u003e next-\u003ebase) {\n-\t\t\tphys_addr_t this_end, next_end;\n-\n-\t\t\tthis_end = this-\u003ebase + this-\u003esize;\n-\t\t\tnext_end = next-\u003ebase + next-\u003esize;\n-\t\t\tpr_err(\"OVERLAP DETECTED!\\n%s (%pa--%pa) overlaps with %s (%pa--%pa)\\n\",\n-\t\t\t this-\u003ename, \u0026this-\u003ebase, \u0026this_end,\n-\t\t\t next-\u003ename, \u0026next-\u003ebase, \u0026next_end);\n-\t\t}\n-\t}\n-}\n-\n-/\n- fdt_scan_reserved_mem_late() - Scan FDT and initialize remaining reserved\n- * memory regions.\n- \n- This function is used to scan again through the DT and initialize the\n- * \"static\" reserved memory regions, that are defined using the \"reg\"\n- * property. Each such region is then initialized with its specific init\n- * function and stored in the global reserved_mem array.\n+ * __reserved_mem_init_reg() - initialize a static reserved memory region\n+ * described in the first entry in 'reg' property\n /\n-void __init fdt_scan_reserved_mem_late(void)\n+static int __init __reserved_mem_init_reg(unsigned long node,\n+\t\t\t\t\t const char uname)\n {\n-\tconst void fdt = initial_boot_params;\n \tphys_addr_t base, size;\n-\tint node, child;\n-\n-\tif (!fdt)\n-\t\treturn;\n-\n-\tnode = fdt_path_offset(fdt, \"/reserved-memory\");\n-\tif (node \u003c 0) {\n-\t\tpr_info(\"Reserved memory: No reserved-memory node in the DT\\n\");\n-\t\treturn;\n-\t}\n-\n-\t/ Attempt dynamic allocation of a new reserved_mem array /\n-\tif (alloc_reserved_mem_array())\n-\t\treturn;\n-\n-\tif (__reserved_mem_check_root(node)) {\n-\t\tpr_err(\"Reserved memory: unsupported node format, ignoring\\n\");\n-\t\treturn;\n-\t}\n-\n-\tfdt_for_each_subnode(child, fdt, node) {\n-\t\tconst __be32 prop;\n-\t\tconst char uname;\n-\t\tu64 b, s;\n-\t\tint ret;\n-\t\tint len;\n-\n-\t\tif (!of_fdt_device_is_available(fdt, child))\n-\t\t\tcontinue;\n-\n-\t\tprop = of_flat_dt_get_addr_size_prop(child, \"reg\", \u0026len);\n-\t\tif (!prop \|\| !len)\n-\t\t\tcontinue;\n-\n-\t\tret = fdt_validate_reserved_mem_node(child, NULL);\n-\t\tif (ret \u0026\u0026 ret != -ENODEV)\n-\t\t\tcontinue;\n-\n-\t\tof_flat_dt_read_addr_size(prop, 0, \u0026b, \u0026s);\n-\t\tbase = b;\n-\t\tsize = s;\n-\n-\t\tif (size) {\n-\t\t\tuname = fdt_get_name(fdt, child, NULL);\n-\t\t\tfdt_init_reserved_mem_node(child, uname, base, size);\n-\t\t}\n-\t}\n-\n-\t/ check for overlapping reserved regions /\n-\t__rmem_check_for_overlap();\n-}\n-\n-static int __init __reserved_mem_alloc_size(unsigned long node, const char uname);\n-\n-/\n- fdt_scan_reserved_mem() - reserve and allocate memory occupied by\n- * reserved memory regions.\n- \n- This function is used to scan through the FDT and mark memory occupied\n- * by all static (defined by the \"reg\" property) reserved memory regions.\n- * Then memory for all dynamic regions (defined by size \u0026 alignment) is\n- * allocated, a region specific init function is called and region information\n- * is stored in the reserved_mem array.\n- /\n-int __init fdt_scan_reserved_mem(void)\n-{\n-\tint node, child;\n-\tint dynamic_nodes_cnt = 0, count = 0;\n-\tint dynamic_nodes[MAX_RESERVED_REGIONS];\n-\tconst void fdt = initial_boot_params;\n-\n-\tnode = fdt_path_offset(fdt, \"/reserved-memory\");\n-\tif (node \u003c 0) {\n-\t\ttotal_reserved_mem_cnt = 0;\n-\t\treturn -ENODEV;\n-\t}\n-\n-\tif (__reserved_mem_check_root(node) != 0) {\n-\t\tpr_err(\"Reserved memory: unsupported node format, ignoring\\n\");\n-\t\ttotal_reserved_mem_cnt = 0;\n-\t\treturn -EINVAL;\n-\t}\n-\n-\tfdt_for_each_subnode(child, fdt, node) {\n-\t\tconst char uname;\n-\t\tint err;\n-\n-\t\tif (!of_fdt_device_is_available(fdt, child))\n-\t\t\tcontinue;\n+\tconst __be32 prop;\n+\tint len, err;\n+\tu64 b, s;\n \n-\t\tuname = fdt_get_name(fdt, child, NULL);\n+\tprop = of_flat_dt_get_addr_size_prop(node, \"reg\", \u0026len);\n+\tif (!prop \|\| !len)\n+\t\treturn -ENOENT;\n \n-\t\terr = __reserved_mem_reserve_reg(child, uname);\n-\t\tif (!err)\n-\t\t\tcount++;\n+\terr = fdt_validate_reserved_mem_node(node, NULL);\n+\tif (err \u0026\u0026 err != -ENODEV)\n+\t\treturn err;\n \n-\t\t/\n-\t\t Save the nodes for the dynamically-placed regions\n-\t\t * into an array which will be used for allocation right\n-\t\t * after all the statically-placed regions are reserved\n-\t\t * or marked as no-map. This is done to avoid dynamically\n-\t\t * allocating from one of the statically-placed regions.\n-\t\t /\n-\t\tif (err != -ENOENT \|\| !of_get_flat_dt_prop(child, \"size\", NULL))\n-\t\t\tcontinue;\n+\tof_flat_dt_read_addr_size(prop, 0, \u0026b, \u0026s);\n+\tbase = b;\n+\tsize = s;\n \n-\t\tif (dynamic_nodes_cnt == MAX_RESERVED_REGIONS) {\n-\t\t\tpr_err(\"too many defined dynamic regions, skip '%s'\\n\",\n-\t\t\t uname);\n-\t\t\tcontinue;\n-\t\t}\n+\tif (!size)\n+\t\treturn -ENOENT;\n \n-\t\tdynamic_nodes[dynamic_nodes_cnt] = child;\n-\t\tdynamic_nodes_cnt++;\n-\t}\n-\tfor (int i = 0; i \u003c dynamic_nodes_cnt; i++) {\n-\t\tconst char uname;\n-\t\tint err;\n-\n-\t\tchild = dynamic_nodes[i];\n-\t\tuname = fdt_get_name(fdt, child, NULL);\n-\t\terr = __reserved_mem_alloc_size(child, uname);\n-\t\tif (!err)\n-\t\t\tcount++;\n-\t}\n-\ttotal_reserved_mem_cnt = count;\n+\tfdt_init_reserved_mem_node(node, uname, base, size);\n \treturn 0;\n }\n \n@@ -523,6 +311,185 @@ static int __init __reserved_mem_alloc_size(unsigned long node, const char unam\n \treturn 0;\n }\n \n+/\n+ * __reserved_mem_check_root() - check if #size-cells, #address-cells provided\n+ * in /reserved-memory matches the values supported by the current implementation,\n+ * also check if ranges property has been provided\n+ /\n+static int __init __reserved_mem_check_root(unsigned long node)\n+{\n+\tconst __be32 prop;\n+\n+\tprop = of_get_flat_dt_prop(node, \"#size-cells\", NULL);\n+\tif (!prop \|\| be32_to_cpup(prop) != dt_root_size_cells)\n+\t\treturn -EINVAL;\n+\n+\tprop = of_get_flat_dt_prop(node, \"#address-cells\", NULL);\n+\tif (!prop \|\| be32_to_cpup(prop) != dt_root_addr_cells)\n+\t\treturn -EINVAL;\n+\n+\tprop = of_get_flat_dt_prop(node, \"ranges\", NULL);\n+\tif (!prop)\n+\t\treturn -EINVAL;\n+\treturn 0;\n+}\n+\n+static int __init __rmem_cmp(const void a, const void b)\n+{\n+\tconst struct reserved_mem ra = a, rb = b;\n+\n+\tif (ra-\u003ebase \u003c rb-\u003ebase)\n+\t\treturn -1;\n+\n+\tif (ra-\u003ebase \u003e rb-\u003ebase)\n+\t\treturn 1;\n+\n+\t/\n+\t Put the dynamic allocations (address == 0, size == 0) before static\n+\t * allocations at address 0x0 so that overlap detection works\n+\t * correctly.\n+\t /\n+\tif (ra-\u003esize \u003c rb-\u003esize)\n+\t\treturn -1;\n+\tif (ra-\u003esize \u003e rb-\u003esize)\n+\t\treturn 1;\n+\n+\treturn 0;\n+}\n+\n+static void __init __rmem_check_for_overlap(void)\n+{\n+\tint i;\n+\n+\tif (reserved_mem_count \u003c 2)\n+\t\treturn;\n+\n+\tsort(reserved_mem, reserved_mem_count, sizeof(reserved_mem[0]),\n+\t __rmem_cmp, NULL);\n+\tfor (i = 0; i \u003c reserved_mem_count - 1; i++) {\n+\t\tstruct reserved_mem this, next;\n+\n+\t\tthis = \u0026reserved_mem[i];\n+\t\tnext = \u0026reserved_mem[i + 1];\n+\n+\t\tif (this-\u003ebase + this-\u003esize \u003e next-\u003ebase) {\n+\t\t\tphys_addr_t this_end, next_end;\n+\n+\t\t\tthis_end = this-\u003ebase + this-\u003esize;\n+\t\t\tnext_end = next-\u003ebase + next-\u003esize;\n+\t\t\tpr_err(\"OVERLAP DETECTED!\\n%s (%pa--%pa) overlaps with %s (%pa--%pa)\\n\",\n+\t\t\t this-\u003ename, \u0026this-\u003ebase, \u0026this_end,\n+\t\t\t next-\u003ename, \u0026next-\u003ebase, \u0026next_end);\n+\t\t}\n+\t}\n+}\n+\n+/\n+ * fdt_scan_reserved_mem() - reserve and allocate memory occupied by\n+ * reserved memory regions.\n+ \n+ This function is used to scan through the FDT, mark all static (defined by\n+ * the \"reg\" property) reserved memory regions as reserved or no-map. Then\n+ * the reserved_mem array is allocated and a region specific init function\n+ * is called for each static region. Finally, memory for all dynamic regions\n+ * (defined by size \u0026 alignment) is allocated and their init functions are\n+ * called. Region information is stored in the reserved_mem array.\n+ /\n+int __init fdt_scan_reserved_mem(void)\n+{\n+\tstruct reserved_mem array, map;\n+\tbool bottom_up = memblock_bottom_up();\n+\tsize_t array_bytes;\n+\tint node, child, cnt = 0;\n+\tconst void fdt = initial_boot_params;\n+\n+\tnode = fdt_path_offset(fdt, \"/reserved-memory\");\n+\tif (node \u003c 0)\n+\t\treturn -ENODEV;\n+\n+\tif (__reserved_mem_check_root(node) != 0) {\n+\t\tpr_err(\"Reserved memory: unsupported node format, ignoring\\n\");\n+\t\treturn -EINVAL;\n+\t}\n+\n+\t/* First pass: reserve the statically-placed regions /\n+\tfdt_for_each_subnode(child, fdt, node) {\n+\t\tint len;\n+\n+\t\tif (!of_fdt_device_is_available(fdt, child))\n+\t\t\tcontinue;\n+\n+\t\t/ static regions use 'reg', dynamic ones use 'size' /\n+\t\tif ((of_flat_dt_get_addr_size_prop(child, \"reg\", \u0026len) \u0026\u0026 len) \|\|\n+\t\t (of_get_flat_dt_prop(child, \"size\", \u0026len) \u0026\u0026 len))\n+\t\t\tcnt++;\n+\n+\t\t__reserved_mem_reserve_reg(child,\n+\t\t\t\t\t fdt_get_name(fdt, child, NULL));\n+\t}\n+\n+\tif (reserved_mem_reserve_failed)\n+\t\tpr_err(\"Some reserved memory regions could not be reserved, system might be unstable. Please fix the device-tree.\\n\");\n+\n+\tif (!cnt)\n+\t\treturn 0;\n+\n+\tarray_bytes = array_size(cnt, sizeof(array));\n+\t/\n+\t Allocate bottom-up, as some architectures (e.g. Xtensa, C-SKY,\n+\t * MIPS32) don't limit memblock to lowmem yet at this point.\n+\t /\n+\tmemblock_set_bottom_up(true);\n+\tarray = memblock_alloc_raw(array_bytes, SMP_CACHE_BYTES);\n+\tmemblock_set_bottom_up(bottom_up);\n+\tif (!array) {\n+\t\tpr_err(\"Failed to allocate memory for reserved_mem array\\n\");\n+\t\treturn -ENOMEM;\n+\t}\n+\n+\tmap = early_array_map(array, array_bytes);\n+\tif (!map) {\n+\t\tpr_err(\"Failed to map memory for reserved_mem array\\n\");\n+\t\tmemblock_free(array, array_bytes);\n+\t\treturn -ENOMEM;\n+\t}\n+\tmemset(map, 0, array_bytes);\n+\n+\treserved_mem = map;\n+\ttotal_reserved_mem_cnt = cnt;\n+\n+\t/ Second pass: initialize the static regions /\n+\tfdt_for_each_subnode(child, fdt, node) {\n+\t\tif (!of_fdt_device_is_available(fdt, child))\n+\t\t\tcontinue;\n+\n+\t\t__reserved_mem_init_reg(child, fdt_get_name(fdt, child, NULL));\n+\t}\n+\n+\t/\n+\t * Allocate the dynamically-placed regions only after all the\n+\t * statically-placed ones are reserved, to avoid overlapping with them.\n+\t /\n+\tfdt_for_each_subnode(child, fdt, node) {\n+\t\tint len;\n+\n+\t\tif (!of_fdt_device_is_available(fdt, child) \|\|\n+\t\t (of_flat_dt_get_addr_size_prop(child, \"reg\", \u0026len) \u0026\u0026 len))\n+\t\t\tcontinue;\n+\n+\t\t__reserved_mem_alloc_size(child,\n+\t\t\t\t\t fdt_get_name(fdt, child, NULL));\n+\t}\n+\n+\t/ Check for overlapping reserved regions /\n+\t__rmem_check_for_overlap();\n+\n+\t/ Switch to the permanent address of the array */\n+\tearly_array_unmap(map, array_bytes);\n+\treserved_mem = array;\n+\treturn 0;\n+}\n+\n extern const struct of_device_id __reservedmem_of_table[];\n static const struct of_device_id __rmem_of_table_sentinel\n \t__used __section(\"__reservedmem_of_table_end\");\n" }
2/1	2026/10/15 11:30	agent	patch-evaluator	1m Model: core Args: null Results: { "EnableConfigs": null, "FocusSymbols": [], "Reasoning": "All modified functions (including fdt_scan_reserved_mem, __reserved_mem_init_reg, __reserved_mem_reserve_reg, __rmem_check_for_overlap, and unflatten_device_tree) are marked __init and execute strictly during early boot. Their memory is reclaimed at free_initmem() before user space initializes, making them unreachable by syzkaller. Furthermore, early device tree reserved memory scanning (fdt_scan_reserved_mem via early_init_fdt_scan_reserved_mem) is exclusive to architectures such as ARM, ARM64, PowerPC, and RISC-V, and is not called on the target architecture (amd64).", "WorthFuzzing": false } Instruction: You are an expert Linux kernel maintainer and security engineer. Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller. IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in your workspace. Do NOT rely on internal assumptions. You must actively use your code access tools to inspect the actual source code, callers, and surrounding context. ================================================================================ 1. CORE TRIAGE PHILOSOPHY ================================================================================ The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs, and newly triggered assertions introduced by the patch series. - REACHABILITY IS THE PRIMARY GATE: Fuzzing can only discover bugs in code that can actually execute in standard virtualized environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap). If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed, regardless of whether it adds assertions or complex logic. - DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS: Patch authors routinely label changes as "cleanups", "refactorings", or state "No functional change intended". Do NOT take these claims at face value. Code refactorings that rearrange logic, introduce helper functions, or alter state management in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs. If reachable executable code is modified or refactored, it MUST be fuzzed. - NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED: When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON, VM_WARN_ON, BUG_ON, lockdep_assert) in reachable code paths, it enforces new or stricter invariants. Even if the author believes the invariant always holds, fuzzing is essential to verify whether an unusual sequence of operations can violate it. ================================================================================ 2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA) ================================================================================ Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories: - Non-kernel and non-executable changes: * Modifications to Documentation/, comments, or spelling fixes. * User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/) that do not affect the compiled kernel image (vmlinux) or kernel modules. * Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures. * Build system or Kconfig changes that do not alter compiled C logic. - Structurally unreachable hardware: * Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU. - Unreachable execution paths: * Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during physical PCI hot-unplug or manual sysfs driver unbinding. * Code paths exclusive to architectures other than the target architecture. ================================================================================ 3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA) ================================================================================ Return WorthFuzzing=true whenever the patch touches reachable executable code, including: - Core Subsystems: * Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/), BPF, scheduler, core networking, VFS, or syscall handling. - Refactorings and Code Cleanups: * Any restructuring of reachable data structures, helper abstractions, or algorithm flows. - Runtime Assertions and Defensive Checks: * Any introduction or alteration of assertions (WARN_ON, VM_WARN_ON, BUG_ON, etc.) in reachable paths. - Reachable Drivers and Protocols: Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.). ================================================================================ 4. EXTRACTING FocusSymbols (PREVENTING DILUTION) ================================================================================ When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer: - AVOID UBIQUITOUS LIFECYCLE HOT-PATHS: Do NOT list generic, ubiquitous functions called by almost every program in the corpus (including, but not limited to: general memory allocators and deallocators, page fault and trap handlers, or core synchronization primitives; this is not an exhaustive list). Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused", which severely dilutes fuzzing effort away from the actual changes. - TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS: List functions that specifically implement the logic being added or altered, or direct API entrypoints for the subsystem feature under review. - HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h): Compiler-inlined static functions (such as static inlines in mm/.h or include/linux/.h) lack distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters. If the changes are primarily in static inline helpers, identify non-static, feature-specific caller functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers). ================================================================================ 5. IDENTIFYING EnableConfigs ================================================================================ Identify any specific CONFIG_ options required to properly compile and reach the modified code: - Inspect Kconfig files and #ifdef guards; do not make assumptions. - Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed. - Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4"). Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit fbb3cd8c7b1055d78ff134cad6158f7bca85efee Author: syz-cluster <triage@syzkaller.com> Date: Thu Oct 15 11:30:41 2026 +0000 syz-cluster: applied patch under review diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index ecc9231026224..a58efdcbac7f1 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -1283,9 +1283,6 @@ void __init unflatten_device_tree(void) { void fdt = initial_boot_params; - / Save the statically-placed regions in the reserved_mem array / - fdt_scan_reserved_mem_late(); - / Populate an empty root node when bootloader doesn't provide one / if (!fdt) { fdt = (void ) __dtb_empty_root_begin; diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index 0ae16da066e2c..895f868b4cfa1 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -9,7 +9,6 @@ / #define FDT_ALIGN_SIZE 8 -#define MAX_RESERVED_REGIONS 64 /* * struct alias_prop - Alias property in 'aliases' node @@ -186,7 +185,6 @@ static inline struct device_node __of_get_dma_parent(const struct device_node #endif int fdt_scan_reserved_mem(void); -void __init fdt_scan_reserved_mem_late(void); bool of_fdt_device_is_available(const void blob, unsigned long node); diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c index 8c9d6395d6a39..0fd1683cba011 100644 --- a/drivers/of/of_reserved_mem.c +++ b/drivers/of/of_reserved_mem.c @@ -27,10 +27,10 @@ #include "of_private.h" -static struct reserved_mem reserved_mem_array[MAX_RESERVED_REGIONS] __initdata; -static struct reserved_mem reserved_mem __refdata = reserved_mem_array; -static int total_reserved_mem_cnt = MAX_RESERVED_REGIONS; +static struct reserved_mem reserved_mem __refdata; +static int total_reserved_mem_cnt; static int reserved_mem_count; +static bool reserved_mem_reserve_failed __initdata; static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size, phys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap, @@ -59,57 +59,28 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size, } / - * alloc_reserved_mem_array() - allocate memory for the reserved_mem - * array using memblock - * - * This function is used to allocate memory for the reserved_mem - * array according to the total number of reserved memory regions - * defined in the DT. - * After the new array is allocated, the information stored in - * the initial static array is copied over to this new array and - * the new array is used from this point on. + * On some architectures (e.g. ARM64) the linear mapping is not yet usable + * during the early reserved memory scan, so the array has to be accessed + * through a temporary early mapping. PPC64 runs the scan before early_ioremap + * is initialized, but the memory returned by memblock is already accessible. / -static int __init alloc_reserved_mem_array(void) +#if defined(CONFIG_GENERIC_EARLY_IOREMAP) && !defined(CONFIG_PPC64) +#include <asm/early_ioremap.h> +static inline void early_array_map(void array, size_t size) { - struct reserved_mem new_array; - size_t alloc_size, copy_size, memset_size; - int ret; - - if (!total_reserved_mem_cnt) - return 0; - - alloc_size = array_size(total_reserved_mem_cnt, sizeof(new_array)); - if (alloc_size == SIZE_MAX) { - ret = -EOVERFLOW; - goto fail; - } - - new_array = memblock_alloc(alloc_size, SMP_CACHE_BYTES); - if (!new_array) { - ret = -ENOMEM; - goto fail; - } - - copy_size = array_size(reserved_mem_count, sizeof(new_array)); - if (copy_size == SIZE_MAX) { - memblock_free(new_array, alloc_size); - ret = -EOVERFLOW; - goto fail; - } - - memset_size = alloc_size - copy_size; - - memcpy(new_array, reserved_mem, copy_size); - memset(new_array + reserved_mem_count, 0, memset_size); - - reserved_mem = new_array; - return 0; - -fail: - pr_err("Failed to allocate memory for reserved_mem array with err: %d", ret); - reserved_mem_count = 0; - return ret; + return early_memremap(__pa(array), size); +} +static inline void early_array_unmap(void map, size_t size) +{ + early_memunmap(map, size); +} +#else +static inline void early_array_map(void array, size_t size) +{ + return array; } +static inline void early_array_unmap(void map, size_t size) {} +#endif static void fdt_init_reserved_mem_node(unsigned long node, const char uname, phys_addr_t base, phys_addr_t size); @@ -174,222 +145,39 @@ static int __init __reserved_mem_reserve_reg(unsigned long node, } else { pr_err("Reserved memory: failed to reserve memory for node '%s': base %pa, size %lu MiB\n", uname, &base, (unsigned long)(size / SZ_1M)); + reserved_mem_reserve_failed = true; } return 0; } / - * __reserved_mem_check_root() - check if #size-cells, #address-cells provided - * in /reserved-memory matches the values supported by the current implementation, - * also check if ranges property has been provided - / -static int __init __reserved_mem_check_root(unsigned long node) -{ - const __be32 prop; - - prop = of_get_flat_dt_prop(node, "#size-cells", NULL); - if (!prop \|\| be32_to_cpup(prop) != dt_root_size_cells) - return -EINVAL; - - prop = of_get_flat_dt_prop(node, "#address-cells", NULL); - if (!prop \|\| be32_to_cpup(prop) != dt_root_addr_cells) - return -EINVAL; - - prop = of_get_flat_dt_prop(node, "ranges", NULL); - if (!prop) - return -EINVAL; - return 0; -} - -static int __init __rmem_cmp(const void a, const void b) -{ - const struct reserved_mem ra = a, rb = b; - - if (ra->base < rb->base) - return -1; - - if (ra->base > rb->base) - return 1; - - /* - * Put the dynamic allocations (address == 0, size == 0) before static - * allocations at address 0x0 so that overlap detection works - * correctly. - / - if (ra->size < rb->size) - return -1; - if (ra->size > rb->size) - return 1; - - return 0; -} - -static void __init __rmem_check_for_overlap(void) -{ - int i; - - if (reserved_mem_count < 2) - return; - - sort(reserved_mem, reserved_mem_count, sizeof(reserved_mem[0]), - __rmem_cmp, NULL); - for (i = 0; i < reserved_mem_count - 1; i++) { - struct reserved_mem this, next; - - this = &reserved_mem[i]; - next = &reserved_mem[i + 1]; - - if (this->base + this->size > next->base) { - phys_addr_t this_end, next_end; - - this_end = this->base + this->size; - next_end = next->base + next->size; - pr_err("OVERLAP DETECTED!\n%s (%pa--%pa) overlaps with %s (%pa--%pa)\n", - this->name, &this->base, &this_end, - next->name, &next->base, &next_end); - } - } -} - -/* - * fdt_scan_reserved_mem_late() - Scan FDT and initialize remaining reserved - * memory regions. - * - * This function is used to scan again through the DT and initialize the - * "static" reserved memory regions, that are defined using the "reg" - * property. Each such region is then initialized with its specific init - * function and stored in the global reserved_mem array. + * __reserved_mem_init_reg() - initialize a static reserved memory region + * described in the first entry in 'reg' property / -void __init fdt_scan_reserved_mem_late(void) +static int __init __reserved_mem_init_reg(unsigned long node, + const char uname) { - const void fdt = initial_boot_params; phys_addr_t base, size; - int node, child; - - if (!fdt) - return; - - node = fdt_path_offset(fdt, "/reserved-memory"); - if (node < 0) { - pr_info("Reserved memory: No reserved-memory node in the DT\n"); - return; - } - - / Attempt dynamic allocation of a new reserved_mem array / - if (alloc_reserved_mem_array()) - return; - - if (__reserved_mem_check_root(node)) { - pr_err("Reserved memory: unsupported node format, ignoring\n"); - return; - } - - fdt_for_each_subnode(child, fdt, node) { - const __be32 prop; - const char uname; - u64 b, s; - int ret; - int len; - - if (!of_fdt_device_is_available(fdt, child)) - continue; - - prop = of_flat_dt_get_addr_size_prop(child, "reg", &len); - if (!prop \|\| !len) - continue; - - ret = fdt_validate_reserved_mem_node(child, NULL); - if (ret && ret != -ENODEV) - continue; - - of_flat_dt_read_addr_size(prop, 0, &b, &s); - base = b; - size = s; - - if (size) { - uname = fdt_get_name(fdt, child, NULL); - fdt_init_reserved_mem_node(child, uname, base, size); - } - } - - / check for overlapping reserved regions / - __rmem_check_for_overlap(); -} - -static int __init __reserved_mem_alloc_size(unsigned long node, const char uname); - -/* - * fdt_scan_reserved_mem() - reserve and allocate memory occupied by - * reserved memory regions. - * - * This function is used to scan through the FDT and mark memory occupied - * by all static (defined by the "reg" property) reserved memory regions. - * Then memory for all dynamic regions (defined by size & alignment) is - * allocated, a region specific init function is called and region information - * is stored in the reserved_mem array. - / -int __init fdt_scan_reserved_mem(void) -{ - int node, child; - int dynamic_nodes_cnt = 0, count = 0; - int dynamic_nodes[MAX_RESERVED_REGIONS]; - const void fdt = initial_boot_params; - - node = fdt_path_offset(fdt, "/reserved-memory"); - if (node < 0) { - total_reserved_mem_cnt = 0; - return -ENODEV; - } - - if (__reserved_mem_check_root(node) != 0) { - pr_err("Reserved memory: unsupported node format, ignoring\n"); - total_reserved_mem_cnt = 0; - return -EINVAL; - } - - fdt_for_each_subnode(child, fdt, node) { - const char uname; - int err; - - if (!of_fdt_device_is_available(fdt, child)) - continue; + const __be32 prop; + int len, err; + u64 b, s; - uname = fdt_get_name(fdt, child, NULL); + prop = of_flat_dt_get_addr_size_prop(node, "reg", &len); + if (!prop \|\| !len) + return -ENOENT; - err = __reserved_mem_reserve_reg(child, uname); - if (!err) - count++; + err = fdt_validate_reserved_mem_node(node, NULL); + if (err && err != -ENODEV) + return err; - /* - * Save the nodes for the dynamically-placed regions - * into an array which will be used for allocation right - * after all the statically-placed regions are reserved - * or marked as no-map. This is done to avoid dynamically - * allocating from one of the statically-placed regions. - / - if (err != -ENOENT \|\| !of_get_flat_dt_prop(child, "size", NULL)) - continue; + of_flat_dt_read_addr_size(prop, 0, &b, &s); + base = b; + size = s; - if (dynamic_nodes_cnt == MAX_RESERVED_REGIONS) { - pr_err("too many defined dynamic regions, skip '%s'\n", - uname); - continue; - } + if (!size) + return -ENOENT; - dynamic_nodes[dynamic_nodes_cnt] = child; - dynamic_nodes_cnt++; - } - for (int i = 0; i < dynamic_nodes_cnt; i++) { - const char uname; - int err; - - child = dynamic_nodes[i]; - uname = fdt_get_name(fdt, child, NULL); - err = __reserved_mem_alloc_size(child, uname); - if (!err) - count++; - } - total_reserved_mem_cnt = count; + fdt_init_reserved_mem_node(node, uname, base, size); return 0; } @@ -523,6 +311,185 @@ static int __init __reserved_mem_alloc_size(unsigned long node, const char unam return 0; } +/ + * __reserved_mem_check_root() - check if #size-cells, #address-cells provided + * in /reserved-memory matches the values supported by the current implementation, + * also check if ranges property has been provided + / +static int __init __reserved_mem_check_root(unsigned long node) +{ + const __be32 prop; + + prop = of_get_flat_dt_prop(node, "#size-cells", NULL); + if (!prop \|\| be32_to_cpup(prop) != dt_root_size_cells) + return -EINVAL; + + prop = of_get_flat_dt_prop(node, "#address-cells", NULL); + if (!prop \|\| be32_to_cpup(prop) != dt_root_addr_cells) + return -EINVAL; + + prop = of_get_flat_dt_prop(node, "ranges", NULL); + if (!prop) + return -EINVAL; + return 0; +} + +static int __init __rmem_cmp(const void a, const void b) +{ + const struct reserved_mem ra = a, rb = b; + + if (ra->base < rb->base) + return -1; + + if (ra->base > rb->base) + return 1; + + /* + * Put the dynamic allocations (address == 0, size == 0) before static + * allocations at address 0x0 so that overlap detection works + * correctly. + / + if (ra->size < rb->size) + return -1; + if (ra->size > rb->size) + return 1; + + return 0; +} + +static void __init __rmem_check_for_overlap(void) +{ + int i; + + if (reserved_mem_count < 2) + return; + + sort(reserved_mem, reserved_mem_count, sizeof(reserved_mem[0]), + __rmem_cmp, NULL); + for (i = 0; i < reserved_mem_count - 1; i++) { + struct reserved_mem this, next; + + this = &reserved_mem[i]; + next = &reserved_mem[i + 1]; + + if (this->base + this->size > next->base) { + phys_addr_t this_end, next_end; + + this_end = this->base + this->size; + next_end = next->base + next->size; + pr_err("OVERLAP DETECTED!\n%s (%pa--%pa) overlaps with %s (%pa--%pa)\n", + this->name, &this->base, &this_end, + next->name, &next->base, &next_end); + } + } +} + +/ + * fdt_scan_reserved_mem() - reserve and allocate memory occupied by + * reserved memory regions. + * + * This function is used to scan through the FDT, mark all static (defined by + * the "reg" property) reserved memory regions as reserved or no-map. Then + * the reserved_mem array is allocated and a region specific init function + * is called for each static region. Finally, memory for all dynamic regions + * (defined by size & alignment) is allocated and their init functions are + * called. Region information is stored in the reserved_mem array. + / +int __init fdt_scan_reserved_mem(void) +{ + struct reserved_mem array, map; + bool bottom_up = memblock_bottom_up(); + size_t array_bytes; + int node, child, cnt = 0; + const void fdt = initial_boot_params; + + node = fdt_path_offset(fdt, "/reserved-memory"); + if (node < 0) + return -ENODEV; + + if (__reserved_mem_check_root(node) != 0) { + pr_err("Reserved memory: unsupported node format, ignoring\n"); + return -EINVAL; + } + + /* First pass: reserve the statically-placed regions / + fdt_for_each_subnode(child, fdt, node) { + int len; + + if (!of_fdt_device_is_available(fdt, child)) + continue; + + / static regions use 'reg', dynamic ones use 'size' / + if ((of_flat_dt_get_addr_size_prop(child, "reg", &len) && len) \|\| + (of_get_flat_dt_prop(child, "size", &len) && len)) + cnt++; + + __reserved_mem_reserve_reg(child, + fdt_get_name(fdt, child, NULL)); + } + + if (reserved_mem_reserve_failed) + pr_err("Some reserved memory regions could not be reserved, system might be unstable. Please fix the device-tree.\n"); + + if (!cnt) + return 0; + + array_bytes = array_size(cnt, sizeof(array)); + /* + * Allocate bottom-up, as some architectures (e.g. Xtensa, C-SKY, + * MIPS32) don't limit memblock to lowmem yet at this point. + / + memblock_set_bottom_up(true); + array = memblock_alloc_raw(array_bytes, SMP_CACHE_BYTES); + memblock_set_bottom_up(bottom_up); + if (!array) { + pr_err("Failed to allocate memory for reserved_mem array\n"); + return -ENOMEM; + } + + map = early_array_map(array, array_bytes); + if (!map) { + pr_err("Failed to map memory for reserved_mem array\n"); + memblock_free(array, array_bytes); + return -ENOMEM; + } + memset(map, 0, array_bytes); + + reserved_mem = map; + total_reserved_mem_cnt = cnt; + + / Second pass: initialize the static regions / + fdt_for_each_subnode(child, fdt, node) { + if (!of_fdt_device_is_available(fdt, child)) + continue; + + __reserved_mem_init_reg(child, fdt_get_name(fdt, child, NULL)); + } + + / + * Allocate the dynamically-placed regions only after all the + * statically-placed ones are reserved, to avoid overlapping with them. + / + fdt_for_each_subnode(child, fdt, node) { + int len; + + if (!of_fdt_device_is_available(fdt, child) \|\| + (of_flat_dt_get_addr_size_prop(child, "reg", &len) && len)) + continue; + + __reserved_mem_alloc_size(child, + fdt_get_name(fdt, child, NULL)); + } + + / Check for overlapping reserved regions / + __rmem_check_for_overlap(); + + / Switch to the permanent address of the array */ + early_array_unmap(map, array_bytes); + reserved_mem = array; + return 0; +} + extern const struct of_device_id __reservedmem_of_table[]; static const struct of_device_id __rmem_of_table_sentinel __used __section("__reservedmem_of_table_end");
3/2	2026/10/15 11:30	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 8964 output: 22 thoughts: 492 Thoughts: Fuzzing Feasibility Analysis: Device Tree Patch Okay, let's break this down. We need to decide if this patch is a good candidate for syzkaller fuzzing. Architecture is amd64, patch already applied to HEAD – good to go there. First, let's examine the changes. The diff shows modifications in `drivers/of/fdt.c`, `drivers/of/of_private.h`, and `drivers/of/of_reserved_mem.c`. Looks like functions related to Open Firmware/Device Tree reserved memory are being touched. `fdt_scan_reserved_mem_late()` and `alloc_reserved_mem_array()` are gone, while `fdt_scan_reserved_mem()` has been rewritten, and we see `early_array_map()`, `early_array_unmap()`, and `__reserved_mem_init_reg()` added. Hold on a second... are those all `__init` functions? Let's verify that. And, of course, the `drivers/of/` subsystem is all about Device Tree and reserved memory management, so this is about the early boot process, specifically when it's initialized. Wait... are these functions `__init`? Looks like all the functions related to this patch are marked `__init`. This is a crucial detail. The `fdt_scan_reserved_mem` function clearly runs during early boot. The challenge is this: syzkaller primarily operates in user space after the initial boot sequence. Can syzkaller even target code executed during early boot? Does the modified `fdt_scan_reserved_mem` have any runtime interface? Are there any mechanisms like Device Tree overlays, user space interaction, or syscalls that can trigger `fdt_scan_reserved_mem` or other functions related to this patch? It's scanning the reserved memory and it's happening during the boot, so I need to check for a runtime interface! I'm going to need to dig deeper using grepper or codesearch to see if there's any way to interact with this functionality after the boot process. Otherwise, fuzzing isn't going to be effective here.
4/2	2026/10/15 11:30	tool	grepper	0m Args: { "Expression": "fdt_scan_reserved_mem" } Results: { "Output": "arch/arc/mm/init.c=101=void __init setup_arch_memory(void)\n--\narch/arc/mm/init.c-135-\tearly_init_fdt_reserve_self();\narch/arc/mm/init.c:136:\tearly_init_fdt_scan_reserved_mem();\narch/arc/mm/init.c-137-\n--\narch/arm/mm/init.c=180=void __init arm_memblock_init(const struct machine_desc mdesc)\n--\narch/arm/mm/init.c-192-\narch/arm/mm/init.c:193:\tearly_init_fdt_scan_reserved_mem();\narch/arm/mm/init.c-194-\n--\narch/arm64/mm/init.c=197=void __init arm64_memblock_init(void)\n--\narch/arm64/mm/init.c-300-\narch/arm64/mm/init.c:301:\tearly_init_fdt_scan_reserved_mem();\narch/arm64/mm/init.c-302-}\n--\narch/csky/kernel/setup.c=62=static void __init csky_memblock_init(void)\n--\narch/csky/kernel/setup.c-70-\tearly_init_fdt_reserve_self();\narch/csky/kernel/setup.c:71:\tearly_init_fdt_scan_reserved_mem();\narch/csky/kernel/setup.c-72-\n--\narch/loongarch/kernel/setup.c=355=void __init platform_init(void)\n--\narch/loongarch/kernel/setup.c-366-\narch/loongarch/kernel/setup.c:367:\tearly_init_fdt_scan_reserved_mem();\narch/loongarch/kernel/setup.c-368-\tunflatten_and_copy_device_tree();\n--\narch/microblaze/mm/init.c=165=asmlinkage void __init mmu_init(void)\n--\narch/microblaze/mm/init.c-232-\narch/microblaze/mm/init.c:233:\tearly_init_fdt_scan_reserved_mem();\narch/microblaze/mm/init.c-234-\n--\narch/mips/kernel/setup.c=633=static void __init arch_mem_init(char cmdline_p)\n--\narch/mips/kernel/setup.c-650-\tearly_init_fdt_reserve_self();\narch/mips/kernel/setup.c:651:\tearly_init_fdt_scan_reserved_mem();\narch/mips/kernel/setup.c-652-\n--\narch/nios2/kernel/setup.c=159=void __init setup_arch(char cmdline_p)\n--\narch/nios2/kernel/setup.c-185-\tearly_init_fdt_reserve_self();\narch/nios2/kernel/setup.c:186:\tearly_init_fdt_scan_reserved_mem();\narch/nios2/kernel/setup.c-187-\n--\narch/openrisc/kernel/setup.c=46=static void __init setup_memory(void)\n--\narch/openrisc/kernel/setup.c-88-\tearly_init_fdt_reserve_self();\narch/openrisc/kernel/setup.c:89:\tearly_init_fdt_scan_reserved_mem();\narch/openrisc/kernel/setup.c-90-\n--\narch/powerpc/kernel/prom.c=644=static void __init early_reserve_mem_dt(void)\n--\narch/powerpc/kernel/prom.c-650-\tearly_init_fdt_reserve_self();\narch/powerpc/kernel/prom.c:651:\tearly_init_fdt_scan_reserved_mem();\narch/powerpc/kernel/prom.c-652-\n--\narch/riscv/mm/init.c=221=static void __init setup_bootmem(void)\n--\narch/riscv/mm/init.c-301-\t /\narch/riscv/mm/init.c:302:\tearly_init_fdt_scan_reserved_mem();\narch/riscv/mm/init.c-303-\n--\narch/sh/boards/of-generic.c=112=static void __init sh_of_mem_reserve(void)\n--\narch/sh/boards/of-generic.c-114-\tearly_init_fdt_reserve_self();\narch/sh/boards/of-generic.c:115:\tearly_init_fdt_scan_reserved_mem();\narch/sh/boards/of-generic.c-116-}\n--\narch/um/kernel/dtb.c=13=void uml_dtb_init(void)\n--\narch/um/kernel/dtb.c-25-\narch/um/kernel/dtb.c:26:\t\tearly_init_fdt_scan_reserved_mem();\narch/um/kernel/dtb.c-27-\t}\n--\narch/xtensa/mm/init.c=40=void __init bootmem_init(void)\n--\narch/xtensa/mm/init.c-49-\narch/xtensa/mm/init.c:50:\tearly_init_fdt_scan_reserved_mem();\narch/xtensa/mm/init.c-51-\n--\ndrivers/of/fdt.c=472=static void __init fdt_reserve_elfcorehdr(void)\n--\ndrivers/of/fdt.c-488-/*\ndrivers/of/fdt.c:489: early_init_fdt_scan_reserved_mem() - create reserved memory regions\ndrivers/of/fdt.c-490- \n--\ndrivers/of/fdt.c-494- /\ndrivers/of/fdt.c:495:void __init early_init_fdt_scan_reserved_mem(void)\ndrivers/of/fdt.c-496-{\n--\ndrivers/of/fdt.c-504-\tfdt_reserve_elfcorehdr();\ndrivers/of/fdt.c:505:\tfdt_scan_reserved_mem();\ndrivers/of/fdt.c-506-\n--\ndrivers/of/of_private.h=181=static inline struct device_node __of_get_dma_parent(const struct device_node np)\n--\ndrivers/of/of_private.h-186-\ndrivers/of/of_private.h:187:int fdt_scan_reserved_mem(void);\ndrivers/of/of_private.h-188-\n--\ndrivers/of/of_reserved_mem.c=360=static void __init __rmem_check_for_overlap(void)\n--\ndrivers/of/of_reserved_mem.c-387-/\ndrivers/of/of_reserved_mem.c:388: fdt_scan_reserved_mem() - reserve and allocate memory occupied by\ndrivers/of/of_reserved_mem.c-389- * reserved memory regions.\n--\ndrivers/of/of_reserved_mem.c-397- */\ndrivers/of/of_reserved_mem.c:398:int __init fdt_scan_reserved_mem(void)\ndrivers/of/of_reserved_mem.c-399-{\n--\ninclude/linux/of_fdt.h=74=extern int early_init_dt_scan_chosen_stdout(void);\ninclude/linux/of_fdt.h:75:extern void early_init_fdt_scan_reserved_mem(void);\ninclude/linux/of_fdt.h-76-extern void early_init_fdt_reserve_self(void);\n--\ninclude/linux/of_fdt.h=98=static inline int early_init_dt_scan_chosen_stdout(void) { return -ENODEV; }\ninclude/linux/of_fdt.h:99:static inline void early_init_fdt_scan_reserved_mem(void) {}\ninclude/linux/of_fdt.h-100-static inline void early_init_fdt_reserve_self(void) {}\n" }
5/2	2026/10/15 11:30	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 12090 output: 39 thoughts: 223 Thoughts: Analyzing the Function Call Graph Okay, so I'm looking at this code and, as expected, `fdt_scan_reserved_mem` is only called by `early_init_fdt_scan_reserved_mem()`, which is designated as `__init`. That's standard initialization stuff. Now, a quick question pops into my head: on `amd64` – x86_64, does it even use `fdt_scan_reserved_mem` or `early_init_fdt_scan_reserved_mem`? I should probably confirm that. Hold on, let me quickly check who does call `early_init_fdt_scan_reserved_mem()`. Alright, here's the list: `arch/arc`, `arch/arm`, `arch/arm64`, `arch/csky`, `arch/loongarch`, `arch/microblaze`, `arch/mips`, `arch/nios2`, `arch/openrisc`, `arch/powerpc`, `arch/riscv`, `arch/sh`, `arch/um`, and `arch/xtensa`. Hmm, interesting, quite a few architectures. But wait, x86 isn't on that list. Is that an oversight? Let me make sure that it's not buried somewhere else. I'll need to double-check the `arch/x86/` directory just to be absolutely certain.
6/2	2026/10/15 11:31	tool	grepper	0m Error: no matches Args: { "Expression": "early_init_fdt\|unflatten_device_tree", "PathPrefixes": [ "arch/x86" ] } Results: { "error": "no matches" }
7/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 12680 output: 39 thoughts: 62 Thoughts: Okay, here's my thought process on this, presented as a first-person expert summary: Initial Device Tree Confusion on x86 Architecture Hmm, this is curious. I'm looking at the x86 architecture code and I was expecting to see calls to `early_init_fdt` or `unflatten_device_tree`, but I'm not seeing them at all. That's unexpected, especially given the increasing reliance on device trees. I know how essential they are for hardware description these days, and how important they are for making hardware portable between operating systems. Okay, something's not adding up. Before jumping to conclusions, let's do a quick and dirty check. I'll run a grep search within the `arch/x86` directory. Let's look for anything that even hints at the existence of a device tree. I'll search for the strings "fdt", "of_", and "device_tree". It's possible the functions are called something completely different, or are conditionally compiled based on a specific configuration, or even are part of a library that I am unaware of. This will help me either confirm my initial impression, or reveal an unexpected dependency or alternative approach. I need to be thorough.
8/2	2026/10/15 11:31	tool	grepper	0m Args: { "Expression": "of_reserved_mem\|reserved_mem\|fdt_", "PathPrefixes": [ "arch/x86" ] } Results: { "Output": "arch/x86/include/asm/iommu.h=44=static inline int __init\narch/x86/include/asm/iommu.h:45:arch_rmrr_sanity_check(struct acpi_dmar_reserved_memory rmrr)\narch/x86/include/asm/iommu.h-46-{\n--\narch/x86/include/uapi/asm/setup_data.h=85=struct kho_data {\narch/x86/include/uapi/asm/setup_data.h:86:\t__u64 fdt_addr;\narch/x86/include/uapi/asm/setup_data.h:87:\t__u64 fdt_size;\narch/x86/include/uapi/asm/setup_data.h-88-\t__u64 bootmem_addr;\n--\narch/x86/kernel/devicetree.c=339=void __init x86_flattree_get_config(void)\n--\narch/x86/kernel/devicetree.c-348-\t\tdt = early_memremap(initial_dtb, map_len);\narch/x86/kernel/devicetree.c:349:\t\tsize = fdt_totalsize(dt);\narch/x86/kernel/devicetree.c-350-\t\tif (map_len \u003c size) {\n--\narch/x86/kernel/kexec-bzimage64.c=226=static void setup_dtb(struct boot_params params,\n--\narch/x86/kernel/kexec-bzimage64.c-232-\narch/x86/kernel/kexec-bzimage64.c:233:\tdtb_len = fdt_totalsize(initial_boot_params);\narch/x86/kernel/kexec-bzimage64.c-234-\tsd-\u003etype = SETUP_DTB;\n--\narch/x86/kernel/kexec-bzimage64.c=274=static void setup_kho(const struct kimage image, struct boot_params params,\n--\narch/x86/kernel/kexec-bzimage64.c-291-\t/* Add setup data /\narch/x86/kernel/kexec-bzimage64.c:292:\tkho-\u003efdt_addr = image-\u003ekho.fdt;\narch/x86/kernel/kexec-bzimage64.c:293:\tkho-\u003efdt_size = PAGE_SIZE;\narch/x86/kernel/kexec-bzimage64.c-294-\tkho-\u003ebootmem_addr = image-\u003ekho.bootmem-\u003emem;\n--\narch/x86/kernel/kexec-bzimage64.c=301=setup_boot_parameters(struct kimage image, struct boot_params params,\n--\narch/x86/kernel/kexec-bzimage64.c-375-\t\tsetup_data_offset += sizeof(struct setup_data) +\narch/x86/kernel/kexec-bzimage64.c:376:\t\t\t\t fdt_totalsize(initial_boot_params);\narch/x86/kernel/kexec-bzimage64.c-377-\t} else {\n--\narch/x86/kernel/kexec-bzimage64.c=475=static void bzImage64_load(struct kimage image, char kernel,\n--\narch/x86/kernel/kexec-bzimage64.c-574-\t\tkbuf.bufsz += sizeof(struct setup_data) +\narch/x86/kernel/kexec-bzimage64.c:575:\t\t\t fdt_totalsize(initial_boot_params);\narch/x86/kernel/kexec-bzimage64.c-576-#endif\n--\narch/x86/kernel/setup.c=457=static void __init add_kho(u64 phys_addr, u32 data_len)\n--\narch/x86/kernel/setup.c-474-\narch/x86/kernel/setup.c:475:\tkho_populate(kho-\u003efdt_addr, kho-\u003efdt_size, kho-\u003ebootmem_addr, kho-\u003ebootmem_size);\narch/x86/kernel/setup.c-476-\n" }
9/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 14163 output: 40 thoughts: 20 Thoughts: Here's my take on the thought process, summarized as you requested: Diving into the Device Tree on x86 Alright, let's get down to brass tacks. I need to understand how the system's firmware, particularly its Device Tree information, is being handled in the x86 architecture. Given the context, the logical starting point is the heart of the matter: `arch/x86/kernel/devicetree.c`. This file should contain the crucial logic for parsing and utilizing the Device Tree data within the x86 kernel. I expect to find the functions responsible for probing the hardware, extracting device information, and making it available to the rest of the kernel subsystems. I'll need to examine how the kernel detects the Device Tree presence and determines which information from it is relevant, especially in a PC environment where the ACPI or other legacy mechanisms may also be in play. There will likely be crucial initialization routines that get things rolling. My immediate goals are to understand the overall flow of DT information into the kernel, the data structures used to represent it, and the key APIs used to access this information by other parts of the kernel. This file holds the key. Let's see what's in there.
10/2	2026/10/15 11:31	tool	read-file	0m Args: { "File": "arch/x86/kernel/devicetree.c", "FirstLine": 1, "LineCount": 80 } Results: { "Contents": " 1:\t// SPDX-License-Identifier: GPL-2.0\n 2:\t/\n 3:\t Architecture specific OF callbacks.\n 4:\t /\n 5:\t#include \u003clinux/acpi.h\u003e\n 6:\t#include \u003clinux/export.h\u003e\n 7:\t#include \u003clinux/io.h\u003e\n 8:\t#include \u003clinux/interrupt.h\u003e\n 9:\t#include \u003clinux/list.h\u003e\n 10:\t#include \u003clinux/of.h\u003e\n 11:\t#include \u003clinux/of_fdt.h\u003e\n 12:\t#include \u003clinux/of_address.h\u003e\n 13:\t#include \u003clinux/of_platform.h\u003e\n 14:\t#include \u003clinux/of_irq.h\u003e\n 15:\t#include \u003clinux/libfdt.h\u003e\n 16:\t#include \u003clinux/slab.h\u003e\n 17:\t#include \u003clinux/pci.h\u003e\n 18:\t#include \u003clinux/of_pci.h\u003e\n 19:\t#include \u003clinux/initrd.h\u003e\n 20:\t\n 21:\t#include \u003casm/acpi.h\u003e\n 22:\t#include \u003casm/irqdomain.h\u003e\n 23:\t#include \u003casm/hpet.h\u003e\n 24:\t#include \u003casm/apic.h\u003e\n 25:\t#include \u003casm/io_apic.h\u003e\n 26:\t#include \u003casm/pci_x86.h\u003e\n 27:\t#include \u003casm/setup.h\u003e\n 28:\t#include \u003casm/i8259.h\u003e\n 29:\t#include \u003casm/numa.h\u003e\n 30:\t#include \u003casm/prom.h\u003e\n 31:\t\n 32:\t__initdata u64 initial_dtb;\n 33:\tchar __initdata cmd_line[COMMAND_LINE_SIZE];\n 34:\t\n 35:\tint __initdata of_ioapic;\n 36:\t\n 37:\tvoid __init add_dtb(u64 data)\n 38:\t{\n 39:\t\tinitial_dtb = data + offsetof(struct setup_data, data);\n 40:\t}\n 41:\t\n 42:\t/\n 43:\t * CE4100 ids. Will be moved to machine_device_initcall() once we have it.\n 44:\t /\n 45:\tstatic struct of_device_id __initdata ce4100_ids[] = {\n 46:\t\t{ .compatible = \"intel,ce4100-cp\", },\n 47:\t\t{ .compatible = \"isa\", },\n 48:\t\t{ .compatible = \"pci\", },\n 49:\t\t{},\n 50:\t};\n 51:\t\n 52:\tstatic int __init add_bus_probe(void)\n 53:\t{\n 54:\t\tif (!of_have_populated_dt())\n 55:\t\t\treturn 0;\n 56:\t\n 57:\t\treturn of_platform_bus_probe(NULL, ce4100_ids, NULL);\n 58:\t}\n 59:\tdevice_initcall(add_bus_probe);\n 60:\t\n 61:\t#ifdef CONFIG_PCI\n 62:\tstruct device_node pcibios_get_phb_of_node(struct pci_bus bus)\n 63:\t{\n 64:\t\tstruct device_node np;\n 65:\t\n 66:\t\tfor_each_node_by_type(np, \"pci\") {\n 67:\t\t\tconst void prop;\n 68:\t\t\tunsigned int bus_min;\n 69:\t\n 70:\t\t\tprop = of_get_property(np, \"bus-range\", NULL);\n 71:\t\t\tif (!prop)\n 72:\t\t\t\tcontinue;\n 73:\t\t\tbus_min = be32_to_cpup(prop);\n 74:\t\t\tif (bus-\u003enumber == bus_min)\n 75:\t\t\t\treturn np;\n 76:\t\t}\n 77:\t\treturn NULL;\n 78:\t}\n 79:\t\n 80:\tstatic int x86_of_pci_irq_enable(struct pci_dev dev)\n" }
11/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 15603 output: 42 thoughts: 23 Thoughts: Okay, here's my attempt at summarizing the thought process, as requested, targeting an expert user and using the first person: Diving into the Device Tree Handling Alright, I'm heading into `arch/x86/kernel/devicetree.c` again. I need to refresh my memory on exactly how this part of the kernel handles the device tree. I've got a specific issue in mind that I'm trying to trace, and I figure the functions related to DT probing and parsing are likely where the root of the problem lies. Let's dig in and see what insights this section can reveal.
12/2	2026/10/15 11:31	tool	read-file	0m Args: { "File": "arch/x86/kernel/devicetree.c", "FirstLine": 300, "LineCount": 80 } Results: { "Contents": " 300:\t\tmp_register_ioapic(++ioapic_id, r.start, gsi_top, \u0026cfg);\n 301:\t}\n 302:\t\n 303:\tstatic void __init dtb_ioapic_setup(void)\n 304:\t{\n 305:\t\tstruct device_node dn;\n 306:\t\n 307:\t\tfor_each_compatible_node(dn, NULL, \"intel,ce4100-ioapic\")\n 308:\t\t\tdtb_add_ioapic(dn);\n 309:\t\n 310:\t\tif (nr_ioapics) {\n 311:\t\t\tof_ioapic = 1;\n 312:\t\t\treturn;\n 313:\t\t}\n 314:\t\tpr_err(\"Error: No information about IO-APIC in OF.\\n\");\n 315:\t}\n 316:\t#else\n 317:\tstatic void __init dtb_ioapic_setup(void) {}\n 318:\t#endif\n 319:\t\n 320:\tstatic void __init dtb_apic_setup(void)\n 321:\t{\n 322:\t#ifdef CONFIG_X86_LOCAL_APIC\n 323:\t\tdtb_lapic_setup();\n 324:\t\tdtb_cpu_setup();\n 325:\t#endif\n 326:\t\tdtb_ioapic_setup();\n 327:\t}\n 328:\t\n 329:\tstatic void __init x86_dtb_parse_smp_config(void)\n 330:\t{\n 331:\t\tif (!of_have_populated_dt())\n 332:\t\t\treturn;\n 333:\t\n 334:\t\tdtb_setup_hpet();\n 335:\t\tdtb_apic_setup();\n 336:\t\tdtb_wakeup_mailbox_setup();\n 337:\t}\n 338:\t\n 339:\tvoid __init x86_flattree_get_config(void)\n 340:\t{\n 341:\t#ifdef CONFIG_OF_EARLY_FLATTREE\n 342:\t\tu32 size, map_len;\n 343:\t\tvoid dt;\n 344:\t\n 345:\t\tif (initial_dtb) {\n 346:\t\t\tmap_len = max(PAGE_SIZE - (initial_dtb \u0026 ~PAGE_MASK), (u64)128);\n 347:\t\n 348:\t\t\tdt = early_memremap(initial_dtb, map_len);\n 349:\t\t\tsize = fdt_totalsize(dt);\n 350:\t\t\tif (map_len \u003c size) {\n 351:\t\t\t\tearly_memunmap(dt, map_len);\n 352:\t\t\t\tdt = early_memremap(initial_dtb, size);\n 353:\t\t\t\tmap_len = size;\n 354:\t\t\t}\n 355:\t\n 356:\t\t\tearly_init_dt_verify(dt, __pa(dt));\n 357:\t\t}\n 358:\t\n 359:\t\tunflatten_and_copy_device_tree();\n 360:\t\n 361:\t\tif (initial_dtb)\n 362:\t\t\tearly_memunmap(dt, map_len);\n 363:\t#endif\n 364:\t\tif (acpi_disabled \u0026\u0026 of_have_populated_dt())\n 365:\t\t\tx86_init.mpparse.parse_smp_cfg = x86_dtb_parse_smp_config;\n 366:\t}\n" }
13/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 16789 output: 24 thoughts: 67 Thoughts: Here's my take on those thoughts: Investigating Device Tree Initialization on x86 Okay, so `x86_flattree_get_config` doesn't appear to be responsible for the early reservation memory scan using `early_init_fdt_scan_reserved_mem()`. That's a little surprising, because I'd have expected it to be involved. Now, where is that reservation happening? Hmmm, my intuition says it has to be somewhere pretty low-level and close to the device tree flattening, right? Let me double-check - I really should have memorized this code by now - oh, yeah, what about `unflatten_and_copy_device_tree()`? That sounds like it could be the place. Let's dig into `unflatten_and_copy_device_tree()` and see what's really going on there. I'm betting that's where the magic happens.
14/2	2026/10/15 11:31	tool	grepper	0m Args: { "Expression": "unflatten_and_copy_device_tree" } Results: { "Output": "arch/arc/kernel/setup.c=507=void __init setup_arch(char *cmdline_p)\n--\narch/arc/kernel/setup.c-526-\t/ copy flat DT out of .init and then unflatten it /\narch/arc/kernel/setup.c:527:\tunflatten_and_copy_device_tree();\narch/arc/kernel/setup.c-528-\n--\narch/csky/kernel/setup.c=105=void __init setup_arch(char cmdline_p)\n--\narch/csky/kernel/setup.c-119-\narch/csky/kernel/setup.c:120:\tunflatten_and_copy_device_tree();\narch/csky/kernel/setup.c-121-\n--\narch/loongarch/kernel/setup.c=355=void __init platform_init(void)\n--\narch/loongarch/kernel/setup.c-367-\tearly_init_fdt_scan_reserved_mem();\narch/loongarch/kernel/setup.c:368:\tunflatten_and_copy_device_tree();\narch/loongarch/kernel/setup.c-369-\n--\narch/mips/bmips/setup.c=212=void __init device_tree_init(void)\n--\narch/mips/bmips/setup.c-216-\narch/mips/bmips/setup.c:217:\tunflatten_and_copy_device_tree();\narch/mips/bmips/setup.c-218-\n--\narch/mips/cavium-octeon/setup.c=1161=void __init device_tree_init(void)\n--\narch/mips/cavium-octeon/setup.c-1215-\t\tocteon_fill_mac_addresses();\narch/mips/cavium-octeon/setup.c:1216:\tunflatten_and_copy_device_tree();\narch/mips/cavium-octeon/setup.c-1217-\tinit_octeon_system_type();\n--\narch/mips/econet/init.c=90=void __init device_tree_init(void)\narch/mips/econet/init.c-91-{\narch/mips/econet/init.c:92:\tunflatten_and_copy_device_tree();\narch/mips/econet/init.c-93-\n--\narch/mips/generic/init.c=111=void __init device_tree_init(void)\narch/mips/generic/init.c-112-{\narch/mips/generic/init.c:113:\tunflatten_and_copy_device_tree();\narch/mips/generic/init.c-114-\tmips_cpc_probe();\n--\narch/mips/kernel/prom.c=69=void __weak __init device_tree_init(void)\narch/mips/kernel/prom.c-70-{\narch/mips/kernel/prom.c:71:\tunflatten_and_copy_device_tree();\narch/mips/kernel/prom.c-72-}\n--\narch/nios2/kernel/setup.c=159=void __init setup_arch(char cmdline_p)\n--\narch/nios2/kernel/setup.c-187-\narch/nios2/kernel/setup.c:188:\tunflatten_and_copy_device_tree();\narch/nios2/kernel/setup.c-189-\n--\narch/openrisc/kernel/setup.c=225=void __init setup_arch(char cmdline_p)\n--\narch/openrisc/kernel/setup.c-229-\narch/openrisc/kernel/setup.c:230:\tunflatten_and_copy_device_tree();\narch/openrisc/kernel/setup.c-231-\n--\narch/riscv/kernel/setup.c=309=void __init setup_arch(char cmdline_p)\n--\narch/riscv/kernel/setup.c-330-#if IS_ENABLED(CONFIG_BUILTIN_DTB)\narch/riscv/kernel/setup.c:331:\t\tunflatten_and_copy_device_tree();\narch/riscv/kernel/setup.c-332-#else\n--\narch/sh/kernel/setup.c=263=void __init setup_arch(char cmdline_p)\n--\narch/sh/kernel/setup.c-319-#ifdef CONFIG_BUILTIN_DTB\narch/sh/kernel/setup.c:320:\tunflatten_and_copy_device_tree();\narch/sh/kernel/setup.c-321-#else\n--\narch/x86/kernel/devicetree.c=339=void __init x86_flattree_get_config(void)\n--\narch/x86/kernel/devicetree.c-358-\narch/x86/kernel/devicetree.c:359:\tunflatten_and_copy_device_tree();\narch/x86/kernel/devicetree.c-360-\n--\narch/xtensa/kernel/setup.c=277=void __init setup_arch(char cmdline_p)\n--\narch/xtensa/kernel/setup.c-357-\tkasan_init();\narch/xtensa/kernel/setup.c:358:\tunflatten_and_copy_device_tree();\narch/xtensa/kernel/setup.c-359-\n--\ndrivers/of/fdt.c=1282=void __init unflatten_device_tree(void)\n--\ndrivers/of/fdt.c-1308-/\ndrivers/of/fdt.c:1309: unflatten_and_copy_device_tree - copy and create tree of device_nodes from flat blob\ndrivers/of/fdt.c-1310- \n--\ndrivers/of/fdt.c-1318- /\ndrivers/of/fdt.c:1319:void __init unflatten_and_copy_device_tree(void)\ndrivers/of/fdt.c-1320-{\n--\ninclude/linux/of_fdt.h=92=extern void unflatten_device_tree(void);\ninclude/linux/of_fdt.h:93:extern void unflatten_and_copy_device_tree(void);\ninclude/linux/of_fdt.h-94-extern void early_init_devtree(void );\n--\ninclude/linux/of_fdt.h=102=static inline void unflatten_device_tree(void) {}\ninclude/linux/of_fdt.h:103:static inline void unflatten_and_copy_device_tree(void) {}\ninclude/linux/of_fdt.h-104-#endif / CONFIG_OF_EARLY_FLATTREE */\n" }
15/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 18865 output: 37 thoughts: 27 Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and presented in the first person: Diving into the FDT Driver Alright, time to get to the heart of the matter. I need to take a look at the Flattened Device Tree driver, specifically the `drivers/of/fdt.c` file. Given the task at hand, I strongly suspect the problem's going to be somewhere in the section around lines 1280 to 1330. That's a key area dealing with [insert your expert knowledge about that specific part of the FDT driver here, e.g., "how it handles resource mapping", or "the parsing of specific property types", or "interrupt controller initialization", etc. - this would be based on the user's expertise.]. I'll go directly to that region to see if something jumps out at me. Hopefully, I'll be able to spot the root cause quickly by focusing my attention there.
16/2	2026/10/15 11:31	tool	read-file	0m Args: { "File": "drivers/of/fdt.c", "FirstLine": 1280, "LineCount": 50 } Results: { "Contents": "1280:\t * can be used.\n1281:\t /\n1282:\tvoid __init unflatten_device_tree(void)\n1283:\t{\n1284:\t\tvoid fdt = initial_boot_params;\n1285:\t\n1286:\t\t/* Populate an empty root node when bootloader doesn't provide one /\n1287:\t\tif (!fdt) {\n1288:\t\t\tfdt = (void ) __dtb_empty_root_begin;\n1289:\t\t\t/* fdt_totalsize() will be used for copy size /\n1290:\t\t\tif (fdt_totalsize(fdt) \u003e\n1291:\t\t\t __dtb_empty_root_end - __dtb_empty_root_begin) {\n1292:\t\t\t\tpr_err(\"invalid size in dtb_empty_root\\n\");\n1293:\t\t\t\treturn;\n1294:\t\t\t}\n1295:\t\t\tof_fdt_crc32 = crc32_be(~0, fdt, fdt_totalsize(fdt));\n1296:\t\t\tfdt = copy_device_tree(fdt);\n1297:\t\t}\n1298:\t\n1299:\t\t__unflatten_device_tree(fdt, NULL, \u0026of_root,\n1300:\t\t\t\t\tearly_init_dt_alloc_memory_arch, false);\n1301:\t\n1302:\t\t/ Get pointer to \"/chosen\" and \"/aliases\" nodes for use everywhere /\n1303:\t\tof_alias_scan(early_init_dt_alloc_memory_arch);\n1304:\t\n1305:\t\tunittest_unflatten_overlay_base();\n1306:\t}\n1307:\t\n1308:\t/\n1309:\t unflatten_and_copy_device_tree - copy and create tree of device_nodes from flat blob\n1310:\t \n1311:\t Copies and unflattens the device-tree passed by the firmware, creating the\n1312:\t * tree of struct device_node. It also fills the \"name\" and \"type\"\n1313:\t * pointers of the nodes so the normal device-tree walking functions\n1314:\t * can be used. This should only be used when the FDT memory has not been\n1315:\t * reserved such is the case when the FDT is built-in to the kernel init\n1316:\t * section. If the FDT memory is reserved already then unflatten_device_tree\n1317:\t * should be used instead.\n1318:\t */\n1319:\tvoid __init unflatten_and_copy_device_tree(void)\n1320:\t{\n1321:\t\tif (initial_boot_params)\n1322:\t\t\tinitial_boot_params = copy_device_tree(initial_boot_params);\n1323:\t\n1324:\t\tunflatten_device_tree();\n1325:\t}\n1326:\t\n1327:\t#ifdef CONFIG_SYSFS\n1328:\tstatic int __init of_fdt_raw_init(void)\n1329:\t{\n" }
17/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 19963 output: 43 thoughts: 357 Thoughts: Analyzing the Reserved Memory Changes in the Device Tree Code Okay, here's what's happening. I'm looking at this patch and immediately, I see a significant change in the way reserved memory regions are handled within the device tree code. Specifically, the call to `fdt_scan_reserved_mem_late()` has been removed from `unflatten_device_tree()` within `drivers/of/fdt.c`. The diff clearly shows it's gone. Then, I see it's also gone from the header file, `drivers/of/of_private.h`. And the plot thickens... `drivers/of/of_reserved_mem.c`... the function itself, `fdt_scan_reserved_mem_late()`, has been completely deleted from that file. Furthermore, the remaining function, `fdt_scan_reserved_mem()`, seems to have been rewritten to incorporate the functionality of the deleted `late()` version. My immediate question is: Why? What's the rationale behind this? More importantly, is any of `drivers/of/of_reserved_mem.c` even executable after the initial boot process? The name "late" implied that it was not called initially, so is all of `drivers/of/of_reserved_mem.c` now considered early code only? I need to analyze the code's sections and callers to confirm my suspicions and understand the implications of this change. It looks like I need to read the entire file.
18/2	2026/10/15 11:31	tool	grepper	0m Args: { "Expression": "^(static \|void \|int \|struct \|bool )", "PathPrefixes": [ "drivers/of/of_reserved_mem.c" ] } Results: { "Output": "drivers/of/of_reserved_mem.c-29-\ndrivers/of/of_reserved_mem.c:30:static struct reserved_mem reserved_mem __refdata;\ndrivers/of/of_reserved_mem.c:31:static int total_reserved_mem_cnt;\ndrivers/of/of_reserved_mem.c:32:static int reserved_mem_count;\ndrivers/of/of_reserved_mem.c:33:static bool reserved_mem_reserve_failed __initdata;\ndrivers/of/of_reserved_mem.c-34-\ndrivers/of/of_reserved_mem.c:35:static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,\ndrivers/of/of_reserved_mem.c-36-\tphys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,\n--\ndrivers/of/of_reserved_mem.c-68-#include \u003casm/early_ioremap.h\u003e\ndrivers/of/of_reserved_mem.c:69:static inline void early_array_map(void array, size_t size)\ndrivers/of/of_reserved_mem.c-70-{\n--\ndrivers/of/of_reserved_mem.c-72-}\ndrivers/of/of_reserved_mem.c:73:static inline void early_array_unmap(void map, size_t size)\ndrivers/of/of_reserved_mem.c-74-{\n--\ndrivers/of/of_reserved_mem.c-77-#else\ndrivers/of/of_reserved_mem.c:78:static inline void early_array_map(void array, size_t size)\ndrivers/of/of_reserved_mem.c-79-{\n--\ndrivers/of/of_reserved_mem.c-81-}\ndrivers/of/of_reserved_mem.c:82:static inline void early_array_unmap(void map, size_t size) {}\ndrivers/of/of_reserved_mem.c-83-#endif\ndrivers/of/of_reserved_mem.c-84-\ndrivers/of/of_reserved_mem.c:85:static void fdt_init_reserved_mem_node(unsigned long node, const char uname,\ndrivers/of/of_reserved_mem.c-86-\t\t\t\t phys_addr_t base, phys_addr_t size);\ndrivers/of/of_reserved_mem.c:87:static int fdt_validate_reserved_mem_node(unsigned long node,\ndrivers/of/of_reserved_mem.c-88-\t\t\t\t\t phys_addr_t align);\ndrivers/of/of_reserved_mem.c:89:static int fdt_fixup_reserved_mem_node(unsigned long node,\ndrivers/of/of_reserved_mem.c-90-\t\t\t\t phys_addr_t base, phys_addr_t size);\ndrivers/of/of_reserved_mem.c-91-\ndrivers/of/of_reserved_mem.c:92:static int __init early_init_dt_reserve_memory(phys_addr_t base,\ndrivers/of/of_reserved_mem.c-93-\t\t\t\t\t phys_addr_t size, bool nomap)\n--\ndrivers/of/of_reserved_mem.c-113- /\ndrivers/of/of_reserved_mem.c:114:static int __init __reserved_mem_reserve_reg(unsigned long node,\ndrivers/of/of_reserved_mem.c-115-\t\t\t\t\t const char uname)\n--\ndrivers/of/of_reserved_mem.c-156- /\ndrivers/of/of_reserved_mem.c:157:static int __init __reserved_mem_init_reg(unsigned long node,\ndrivers/of/of_reserved_mem.c-158-\t\t\t\t\t const char uname)\n--\ndrivers/of/of_reserved_mem.c-188- /\ndrivers/of/of_reserved_mem.c:189:static int __init __reserved_mem_alloc_in_range(phys_addr_t size,\ndrivers/of/of_reserved_mem.c-190-\tphys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,\n--\ndrivers/of/of_reserved_mem.c-238- /\ndrivers/of/of_reserved_mem.c:239:static int __init __reserved_mem_alloc_size(unsigned long node, const char uname)\ndrivers/of/of_reserved_mem.c-240-{\n--\ndrivers/of/of_reserved_mem.c-318- /\ndrivers/of/of_reserved_mem.c:319:static int __init __reserved_mem_check_root(unsigned long node)\ndrivers/of/of_reserved_mem.c-320-{\n--\ndrivers/of/of_reserved_mem.c-336-\ndrivers/of/of_reserved_mem.c:337:static int __init __rmem_cmp(const void a, const void b)\ndrivers/of/of_reserved_mem.c-338-{\n--\ndrivers/of/of_reserved_mem.c-359-\ndrivers/of/of_reserved_mem.c:360:static void __init __rmem_check_for_overlap(void)\ndrivers/of/of_reserved_mem.c-361-{\n--\ndrivers/of/of_reserved_mem.c-397- /\ndrivers/of/of_reserved_mem.c:398:int __init fdt_scan_reserved_mem(void)\ndrivers/of/of_reserved_mem.c-399-{\n--\ndrivers/of/of_reserved_mem.c=493=extern const struct of_device_id __reservedmem_of_table[];\ndrivers/of/of_reserved_mem.c:494:static const struct of_device_id __rmem_of_table_sentinel\ndrivers/of/of_reserved_mem.c-495-\t__used __section(\"__reservedmem_of_table_end\");\n--\ndrivers/of/of_reserved_mem.c-507- /\ndrivers/of/of_reserved_mem.c:508:static int __init fdt_fixup_reserved_mem_node(unsigned long node,\ndrivers/of/of_reserved_mem.c-509-\t\t\t\t\tphys_addr_t base, phys_addr_t size)\n--\ndrivers/of/of_reserved_mem.c-536- /\ndrivers/of/of_reserved_mem.c:537:static int __init fdt_validate_reserved_mem_node(unsigned long node, phys_addr_t align)\ndrivers/of/of_reserved_mem.c-538-{\n--\ndrivers/of/of_reserved_mem.c-565- /\ndrivers/of/of_reserved_mem.c:566:static int __init __reserved_mem_init_node(struct reserved_mem rmem,\ndrivers/of/of_reserved_mem.c-567-\t\t\t\t\t unsigned long node)\n--\ndrivers/of/of_reserved_mem.c-601- /\ndrivers/of/of_reserved_mem.c:602:static void __init fdt_init_reserved_mem_node(unsigned long node, const char uname,\ndrivers/of/of_reserved_mem.c-603-\t\t\t\t\t phys_addr_t base, phys_addr_t size)\n--\ndrivers/of/of_reserved_mem.c-646-\ndrivers/of/of_reserved_mem.c:647:struct rmem_assigned_device {\ndrivers/of/of_reserved_mem.c-648-\tstruct device dev;\n--\ndrivers/of/of_reserved_mem.c-652-\ndrivers/of/of_reserved_mem.c:653:static LIST_HEAD(of_rmem_assigned_device_list);\ndrivers/of/of_reserved_mem.c:654:static DEFINE_MUTEX(of_rmem_assigned_device_mutex);\ndrivers/of/of_reserved_mem.c-655-\n--\ndrivers/of/of_reserved_mem.c-670- /\ndrivers/of/of_reserved_mem.c:671:int of_reserved_mem_device_init_by_idx(struct device dev,\ndrivers/of/of_reserved_mem.c-672-\t\t\t\t struct device_node np, int idx)\n--\ndrivers/of/of_reserved_mem.c=717=EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_idx);\n--\ndrivers/of/of_reserved_mem.c-727- /\ndrivers/of/of_reserved_mem.c:728:int of_reserved_mem_device_init_by_name(struct device dev,\ndrivers/of/of_reserved_mem.c-729-\t\t\t\t\tstruct device_node np,\n--\ndrivers/of/of_reserved_mem.c=736=EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_name);\n--\ndrivers/of/of_reserved_mem.c-744- /\ndrivers/of/of_reserved_mem.c:745:void of_reserved_mem_device_release(struct device dev)\ndrivers/of/of_reserved_mem.c-746-{\n--\ndrivers/of/of_reserved_mem.c=764=EXPORT_SYMBOL_GPL(of_reserved_mem_device_release);\ndrivers/of/of_reserved_mem.c-765-\ndrivers/of/of_reserved_mem.c:766:static void devm_of_reserved_mem_device_release(struct device dev, void res)\ndrivers/of/of_reserved_mem.c-767-{\n--\ndrivers/of/of_reserved_mem.c-770-\ndrivers/of/of_reserved_mem.c:771:static int devm_of_reserved_mem_device_init_by_idx(struct device dev,\ndrivers/of/of_reserved_mem.c-772-\t\t\t\t\t\t struct device_node np, int idx)\n--\ndrivers/of/of_reserved_mem.c-803- /\ndrivers/of/of_reserved_mem.c:804:int devm_of_reserved_mem_device_init(struct device dev)\ndrivers/of/of_reserved_mem.c-805-{\n--\ndrivers/of/of_reserved_mem.c=808=EXPORT_SYMBOL_GPL(devm_of_reserved_mem_device_init);\n--\ndrivers/of/of_reserved_mem.c-818- /\ndrivers/of/of_reserved_mem.c:819:struct reserved_mem of_reserved_mem_lookup(struct device_node np)\ndrivers/of/of_reserved_mem.c-820-{\n--\ndrivers/of/of_reserved_mem.c=835=EXPORT_SYMBOL_GPL(of_reserved_mem_lookup);\n--\ndrivers/of/of_reserved_mem.c-848- /\ndrivers/of/of_reserved_mem.c:849:int of_reserved_mem_region_to_resource(const struct device_node np,\ndrivers/of/of_reserved_mem.c-850-\t\t\t\t unsigned int idx, struct resource res)\n--\ndrivers/of/of_reserved_mem.c=870=EXPORT_SYMBOL_GPL(of_reserved_mem_region_to_resource);\n--\ndrivers/of/of_reserved_mem.c-883- /\ndrivers/of/of_reserved_mem.c:884:int of_reserved_mem_region_to_resource_byname(const struct device_node np,\ndrivers/of/of_reserved_mem.c-885-\t\t\t\t\t const char name,\n--\ndrivers/of/of_reserved_mem.c=899=EXPORT_SYMBOL_GPL(of_reserved_mem_region_to_resource_byname);\n--\ndrivers/of/of_reserved_mem.c-910- /\ndrivers/of/of_reserved_mem.c:911:int of_reserved_mem_region_count(const struct device_node *np)\ndrivers/of/of_reserved_mem.c-912-{\n" }
19/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 23802 output: 26 thoughts: 1095 Thoughts: Analyzing the Unreachability of Modified Code Okay, so I'm looking at this patch, and the first thing that jumps out is that every single function it touches is marked `__init`. That's a huge red flag. Specifically, I see: 1. In `drivers/of/fdt.c`, `unflatten_device_tree` is `void __init unflatten_device_tree(void)` and the patch removes `fdt_scan_reserved_mem_late()`. 2. `drivers/of/of_private.h` removes `void __init fdt_scan_reserved_mem_late(void);` and some `#define`s. 3. In `drivers/of/of_reserved_mem.c` a whole host of functions are `__init`: `early_array_map`, `early_array_unmap`, `__reserved_mem_reserve_reg`, `__reserved_mem_init_reg`, `__reserved_mem_check_root`, `__rmem_cmp`, `__rmem_check_for_overlap`, and `fdt_scan_reserved_mem`. Now, I need to remember: `__init` code is discarded and freed after the kernel boot process completes! This happens during `free_initmem()` in `init/main.c`. Once userspace starts, which is when syzkaller runs its fuzzing, that section of memory is gone. Any attempt to execute `__init` functions after boot is going to result in a crash, page fault, or invalid instruction error. My immediate question is: can syzkaller ever execute `__init` code? The answer is no, because that memory is freed before `init` (PID 1) runs. So, let's go back to the triage philosophy: "REACHABILITY IS THE PRIMARY GATE." We only fuzz code that can actually be executed. The instructions are very clear: "Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories: ... - Unreachable execution paths" Therefore, code that's only executed during boot or that is architecturally unreachable is not worth fuzzing. My mind immediately goes to `__init` code and whether the target architecture, `amd64` (x86-64), could even reach that code. Let's see if `fdt_scan_reserved_mem` is ever called on `amd64`. I'll check every call to `fdt_scan_reserved_mem` or `early_init_fdt_scan_reserved_mem`: The grep found it in: * `arch/arc/mm/init.c` * `arch/arm/mm/init.c` * `arch/arm64/mm/init.c` * `arch/csky/kernel/setup.c` * `arch/loongarch/kernel/setup.c` * `arch/microblaze/mm/init.c` * `arch/mips/kernel/setup.c` * `arch/nios2/kernel/setup.c` * `arch/openrisc/kernel/setup.c` * `arch/powerpc/kernel/prom.c` * `arch/riscv/mm/init.c` * `arch/sh/boards/of-generic.c` * `arch/um/kernel/dtb.c` * `arch/xtensa/mm/init.c` * `drivers/of/fdt.c (inside early_init_fdt_scan_reserved_mem())` However, does `arch/x86` (amd64) call `early_init_fdt_scan_reserved_mem()`? I need to check if anything in x86 calls `early_init_fdt_scan_reserved_mem()`! A quick check shows that there are zero calls to `early_init_fdt_scan_reserved_mem()` or `unflatten_device_tree()` in `arch/x86`. I'll do a global search to be absolutely sure. The conclusion is clear: This patch modifies code that is unreachable on the target architecture. This code is not worth fuzzing, and I should return WorthFuzzing=false.
20/2	2026/10/15 11:31	tool	grepper	0m Args: { "Expression": "early_init_fdt_scan_reserved_mem" } Results: { "Output": "arch/arc/mm/init.c=101=void __init setup_arch_memory(void)\n--\narch/arc/mm/init.c-135-\tearly_init_fdt_reserve_self();\narch/arc/mm/init.c:136:\tearly_init_fdt_scan_reserved_mem();\narch/arc/mm/init.c-137-\n--\narch/arm/mm/init.c=180=void __init arm_memblock_init(const struct machine_desc mdesc)\n--\narch/arm/mm/init.c-192-\narch/arm/mm/init.c:193:\tearly_init_fdt_scan_reserved_mem();\narch/arm/mm/init.c-194-\n--\narch/arm64/mm/init.c=197=void __init arm64_memblock_init(void)\n--\narch/arm64/mm/init.c-300-\narch/arm64/mm/init.c:301:\tearly_init_fdt_scan_reserved_mem();\narch/arm64/mm/init.c-302-}\n--\narch/csky/kernel/setup.c=62=static void __init csky_memblock_init(void)\n--\narch/csky/kernel/setup.c-70-\tearly_init_fdt_reserve_self();\narch/csky/kernel/setup.c:71:\tearly_init_fdt_scan_reserved_mem();\narch/csky/kernel/setup.c-72-\n--\narch/loongarch/kernel/setup.c=355=void __init platform_init(void)\n--\narch/loongarch/kernel/setup.c-366-\narch/loongarch/kernel/setup.c:367:\tearly_init_fdt_scan_reserved_mem();\narch/loongarch/kernel/setup.c-368-\tunflatten_and_copy_device_tree();\n--\narch/microblaze/mm/init.c=165=asmlinkage void __init mmu_init(void)\n--\narch/microblaze/mm/init.c-232-\narch/microblaze/mm/init.c:233:\tearly_init_fdt_scan_reserved_mem();\narch/microblaze/mm/init.c-234-\n--\narch/mips/kernel/setup.c=633=static void __init arch_mem_init(char cmdline_p)\n--\narch/mips/kernel/setup.c-650-\tearly_init_fdt_reserve_self();\narch/mips/kernel/setup.c:651:\tearly_init_fdt_scan_reserved_mem();\narch/mips/kernel/setup.c-652-\n--\narch/nios2/kernel/setup.c=159=void __init setup_arch(char cmdline_p)\n--\narch/nios2/kernel/setup.c-185-\tearly_init_fdt_reserve_self();\narch/nios2/kernel/setup.c:186:\tearly_init_fdt_scan_reserved_mem();\narch/nios2/kernel/setup.c-187-\n--\narch/openrisc/kernel/setup.c=46=static void __init setup_memory(void)\n--\narch/openrisc/kernel/setup.c-88-\tearly_init_fdt_reserve_self();\narch/openrisc/kernel/setup.c:89:\tearly_init_fdt_scan_reserved_mem();\narch/openrisc/kernel/setup.c-90-\n--\narch/powerpc/kernel/prom.c=644=static void __init early_reserve_mem_dt(void)\n--\narch/powerpc/kernel/prom.c-650-\tearly_init_fdt_reserve_self();\narch/powerpc/kernel/prom.c:651:\tearly_init_fdt_scan_reserved_mem();\narch/powerpc/kernel/prom.c-652-\n--\narch/riscv/mm/init.c=221=static void __init setup_bootmem(void)\n--\narch/riscv/mm/init.c-301-\t /\narch/riscv/mm/init.c:302:\tearly_init_fdt_scan_reserved_mem();\narch/riscv/mm/init.c-303-\n--\narch/sh/boards/of-generic.c=112=static void __init sh_of_mem_reserve(void)\n--\narch/sh/boards/of-generic.c-114-\tearly_init_fdt_reserve_self();\narch/sh/boards/of-generic.c:115:\tearly_init_fdt_scan_reserved_mem();\narch/sh/boards/of-generic.c-116-}\n--\narch/um/kernel/dtb.c=13=void uml_dtb_init(void)\n--\narch/um/kernel/dtb.c-25-\narch/um/kernel/dtb.c:26:\t\tearly_init_fdt_scan_reserved_mem();\narch/um/kernel/dtb.c-27-\t}\n--\narch/xtensa/mm/init.c=40=void __init bootmem_init(void)\n--\narch/xtensa/mm/init.c-49-\narch/xtensa/mm/init.c:50:\tearly_init_fdt_scan_reserved_mem();\narch/xtensa/mm/init.c-51-\n--\ndrivers/of/fdt.c=472=static void __init fdt_reserve_elfcorehdr(void)\n--\ndrivers/of/fdt.c-488-/*\ndrivers/of/fdt.c:489: early_init_fdt_scan_reserved_mem() - create reserved memory regions\ndrivers/of/fdt.c-490- \n--\ndrivers/of/fdt.c-494- /\ndrivers/of/fdt.c:495:void __init early_init_fdt_scan_reserved_mem(void)\ndrivers/of/fdt.c-496-{\n--\ninclude/linux/of_fdt.h=74=extern int early_init_dt_scan_chosen_stdout(void);\ninclude/linux/of_fdt.h:75:extern void early_init_fdt_scan_reserved_mem(void);\ninclude/linux/of_fdt.h-76-extern void early_init_fdt_reserve_self(void);\n--\ninclude/linux/of_fdt.h=98=static inline int early_init_dt_scan_chosen_stdout(void) { return -ENODEV; }\ninclude/linux/of_fdt.h:99:static inline void early_init_fdt_scan_reserved_mem(void) {}\ninclude/linux/of_fdt.h-100-static inline void early_init_fdt_reserve_self(void) {}\n" }
21/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 27689 output: 21 thoughts: 79 Thoughts: Here's my thought process, as requested: Investigating the Early FDT Scan on x86/amd64 Okay, so I'm digging into this code and it's looking like `early_init_fdt_scan_reserved_mem()` isn't even used on x86 and amd64 architectures. That's immediately interesting, and raises a flag. I need to understand the control flow. Now, hold on... if that function isn't being called early, what is responsible for calling `fdt_scan_reserved_mem_late()` before this patch was introduced? My intuition tells me there's something else setting up the reserved memory information. Let me see, aha, it's only `unflatten_device_tree()` that calls it. Okay, that's getting clearer. So, who calls `unflatten_device_tree()`? That's the critical link I need. I'll trace that call path back to figure out when the device tree gets unflattened and its reserved memory handled. That should illuminate the behavior before the patch, and explain the current flow.
22/2	2026/10/15 11:31	tool	grepper	0m Args: { "Expression": "unflatten_device_tree\\(" } Results: { "Output": "Documentation/devicetree/usage-model.rst=223=has been parsed, then kernel initialization can proceed in the normal\nDocumentation/devicetree/usage-model.rst:224:way. At some point in this process, unflatten_device_tree() is called\nDocumentation/devicetree/usage-model.rst-225-to convert the data into a more efficient runtime representation.\n--\nDocumentation/kbuild/makefiles.rst=1466=dtc\n--\nDocumentation/kbuild/makefiles.rst-1469- in an init section in the image. Platform code must copy the\nDocumentation/kbuild/makefiles.rst:1470: blob to non-init memory prior to calling unflatten_device_tree().\nDocumentation/kbuild/makefiles.rst-1471-\n--\nDocumentation/translations/zh_CN/devicetree/usage-model.rst=165=early_init_dt_scan_root()用于初始化DT地址空间模型，early_init_dt_scan_memory()\n--\nDocumentation/translations/zh_CN/devicetree/usage-model.rst-173-在电路板被识别后，在早期配置数据被解析后，内核初始化可以以正常方式进行。在\nDocumentation/translations/zh_CN/devicetree/usage-model.rst:174:这个过程中的某个时刻，unflatten_device_tree()被调用以将数据转换成更有\nDocumentation/translations/zh_CN/devicetree/usage-model.rst-175-效的运行时表示。这也是调用机器特定设置钩子的时候，比如ARM上的machine_desc\n--\narch/arm/kernel/setup.c=1096=void __init setup_arch(char cmdline_p)\n--\narch/arm/kernel/setup.c-1165-\narch/arm/kernel/setup.c:1166:\tunflatten_device_tree();\narch/arm/kernel/setup.c-1167-\n--\narch/arm64/kernel/setup.c=281=void __init __no_sanitize_address setup_arch(char cmdline_p)\n--\narch/arm64/kernel/setup.c-341-\tif (acpi_disabled)\narch/arm64/kernel/setup.c:342:\t\tunflatten_device_tree();\narch/arm64/kernel/setup.c-343-\n--\narch/microblaze/kernel/setup.c=51=void __init setup_arch(char cmdline_p)\n--\narch/microblaze/kernel/setup.c-58-\narch/microblaze/kernel/setup.c:59:\tunflatten_device_tree();\narch/microblaze/kernel/setup.c-60-\n--\narch/powerpc/kernel/setup-common.c=917=void __init setup_arch(char cmdline_p)\n--\narch/powerpc/kernel/setup-common.c-926-\t/* Unflatten the device-tree passed by prom_init or kexec /\narch/powerpc/kernel/setup-common.c:927:\tunflatten_device_tree();\narch/powerpc/kernel/setup-common.c-928-\n--\narch/riscv/kernel/setup.c=309=void __init setup_arch(char cmdline_p)\n--\narch/riscv/kernel/setup.c-332-#else\narch/riscv/kernel/setup.c:333:\t\tunflatten_device_tree();\narch/riscv/kernel/setup.c-334-#endif\n--\narch/sh/kernel/setup.c=263=void __init setup_arch(char cmdline_p)\n--\narch/sh/kernel/setup.c-321-#else\narch/sh/kernel/setup.c:322:\tunflatten_device_tree();\narch/sh/kernel/setup.c-323-#endif\n--\narch/um/kernel/dtb.c=13=void uml_dtb_init(void)\n--\narch/um/kernel/dtb.c-28-\narch/um/kernel/dtb.c:29:\tunflatten_device_tree();\narch/um/kernel/dtb.c-30-}\n--\ndrivers/of/fdt.c=270=static int unflatten_dt_nodes(const void blob,\n--\ndrivers/of/fdt.c-350- /\ndrivers/of/fdt.c:351:void __unflatten_device_tree(const void blob,\ndrivers/of/fdt.c-352-\t\t\t struct device_node dad,\n--\ndrivers/of/fdt.c-363-\ndrivers/of/fdt.c:364:\tpr_debug(\" -\u003e unflatten_device_tree()\\n\");\ndrivers/of/fdt.c-365-\n--\ndrivers/of/fdt.c-412-\ndrivers/of/fdt.c:413:\tpr_debug(\" \u003c- unflatten_device_tree()\\n\");\ndrivers/of/fdt.c-414-\treturn mem;\n--\ndrivers/of/fdt.c=438=void of_fdt_unflatten_tree(const unsigned long blob,\n--\ndrivers/of/fdt.c-444-\tmutex_lock(\u0026of_fdt_unflatten_mutex);\ndrivers/of/fdt.c:445:\tmem = __unflatten_device_tree(blob, dad, mynodes, \u0026kernel_tree_alloc,\ndrivers/of/fdt.c-446-\t\t\t\t true);\n--\ndrivers/of/fdt.c=1259=static void __init copy_device_tree(void fdt)\n--\ndrivers/of/fdt.c-1281- /\ndrivers/of/fdt.c:1282:void __init unflatten_device_tree(void)\ndrivers/of/fdt.c-1283-{\n--\ndrivers/of/fdt.c-1298-\ndrivers/of/fdt.c:1299:\t__unflatten_device_tree(fdt, NULL, \u0026of_root,\ndrivers/of/fdt.c-1300-\t\t\t\tearly_init_dt_alloc_memory_arch, false);\n--\ndrivers/of/fdt.c=1319=void __init unflatten_and_copy_device_tree(void)\n--\ndrivers/of/fdt.c-1323-\ndrivers/of/fdt.c:1324:\tunflatten_device_tree();\ndrivers/of/fdt.c-1325-}\n--\ndrivers/of/of_private.h=112=static inline void unittest_unflatten_overlay_base(void) {};\n--\ndrivers/of/of_private.h-114-\ndrivers/of/of_private.h:115:extern void __unflatten_device_tree(const void blob,\ndrivers/of/of_private.h-116-\t\t\t struct device_node dad,\n--\ndrivers/of/unittest.c=3925=void __init unittest_unflatten_overlay_base(void)\n--\ndrivers/of/unittest.c-3971-\ndrivers/of/unittest.c:3972:\t__unflatten_device_tree(new_fdt, NULL, \u0026overlay_base_root,\ndrivers/of/unittest.c-3973-\t\t\t\tdt_alloc_memory, true);\n--\ninclude/linux/of_fdt.h=88=extern const void of_flat_dt_match_machine(const void default_match,\n--\ninclude/linux/of_fdt.h-91-/* Other Prototypes /\ninclude/linux/of_fdt.h:92:extern void unflatten_device_tree(void);\ninclude/linux/of_fdt.h-93-extern void unflatten_and_copy_device_tree(void);\n--\ninclude/linux/of_fdt.h=101=static inline const char of_flat_dt_get_machine_name(void) { return NULL; }\ninclude/linux/of_fdt.h:102:static inline void unflatten_device_tree(void) {}\ninclude/linux/of_fdt.h-103-static inline void unflatten_and_copy_device_tree(void) {}\n" }
23/2	2026/10/15 11:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 30140 output: 37 thoughts: 1672 Thoughts: Analysis of Kernel Patch for Fuzzing Eligibility Okay, let's break this down systematically. I need to determine if this patch makes the affected code worthy of inclusion in the fuzzing scope. First, the target architecture is amd64. I'm seeing a connection to Device Tree (DT) through `x86_flattree_get_config()` and then `unflatten_and_copy_device_tree()`, which calls `unflatten_device_tree()`. If we provide an `initial_dtb`, as in CE4100 or with SETUP_DTB, `unflatten_device_tree()` gets called early during boot, specifically within `setup_arch()`. Then, wait a minute, I notice that `early_init_fdt_scan_reserved_mem()` never runs on x86/amd64. And, after this patch, `fdt_scan_reserved_mem_late()` was completely removed from the `unflatten_device_tree()` function. So, previously, the late scan was there on boot, but now it is gone! Also, `fdt_scan_reserved_mem()` is only called by `early_init_fdt_scan_reserved_mem()`, which itself isn't used on x86/amd64! Here's the critical point: the functions `unflatten_device_tree`, `fdt_scan_reserved_mem`, `__reserved_mem_reserve_reg`, `__reserved_mem_init_reg`, `__reserved_mem_check_root`, `__rmem_cmp`, `__rmem_check_for_overlap`, `early_array_map`, and `early_array_unmap` are all marked `__init`. Now, let's go back to the guidelines on when to exclude from fuzzing (negative criteria): "Code paths exclusive to architectures other than the target architecture." And, critically, "Unreachable execution paths." Can syzkaller fuzz the init code? No. Syzkaller runs after boot. `free_initmem()` reclaims and removes the init code, so by the time syscalls come around, that code's no longer accessible and therefore unfuzzable. Considering the "exclusive to other architectures" rule, `fdt_scan_reserved_mem()` isn't even called on amd64. I should verify this. Looking in `arch/x86`, there are no direct references to the `fdt_scan_reserved_mem()` or `reserved_mem`. Let's search the entire kernel for references. The only caller of `fdt_scan_reserved_mem()` is `early_init_fdt_scan_reserved_mem()` within `drivers/of/fdt.c`. Then, `early_init_fdt_scan_reserved_mem()` is only called on arc, arm, arm64, csky, loongarch, microblaze, mips, nios2, openrisc, powerpc, riscv, sh, um, and xtensa architectures, but not x86/amd64! And now the only call to `fdt_scan_reserved_mem` which existed on x86, which was `fdt_scan_reserved_mem_late()` within `unflatten_device_tree()`, has been removed! The logic inside `fdt_scan_reserved_mem()` is exclusive to those non-x86 architectures. Furthermore, everything modified or added in this patch is `__init` code and runs during early memory setup, before userspace even starts. Let's do a double-check. Is it possible any of these functions could be called at runtime? Let's trace every symbol: 1. `unflatten_device_tree`: `void __init unflatten_device_tree(void)`. Called only in `setup_arch()` or similar early boot functions. All `__init`. 2. `fdt_scan_reserved_mem_late`: Removed. 3. `alloc_reserved_mem_array`: Removed. 4. `early_array_map` / `early_array_unmap`: Static inline. Called only from `fdt_scan_reserved_mem()`. 5. `__reserved_mem_reserve_reg`: `static int __init __reserved_mem_reserve_reg(...)`. Called only from `fdt_scan_reserved_mem()`. 6. `__reserved_mem_init_reg`: `static int __init __reserved_mem_init_reg(...)`. Called only from `fdt_scan_reserved_
24/2	2026/10/15 11:32	tool	grepper	0m Args: { "Expression": "reserved_mem\\b", "PathPrefixes": [ "drivers/of/of_reserved_mem.c" ] } Results: { "Output": "drivers/of/of_reserved_mem.c-21-#include \u003clinux/sizes.h\u003e\ndrivers/of/of_reserved_mem.c:22:#include \u003clinux/of_reserved_mem.h\u003e\ndrivers/of/of_reserved_mem.c-23-#include \u003clinux/sort.h\u003e\n--\ndrivers/of/of_reserved_mem.c-29-\ndrivers/of/of_reserved_mem.c:30:static struct reserved_mem reserved_mem __refdata;\ndrivers/of/of_reserved_mem.c-31-static int total_reserved_mem_cnt;\n--\ndrivers/of/of_reserved_mem.c=189=static int __init __reserved_mem_alloc_in_range(phys_addr_t size,\n--\ndrivers/of/of_reserved_mem.c-197-\tfor (i = 0; i \u003c reserved_mem_count; i++) {\ndrivers/of/of_reserved_mem.c:198:\t\tstruct reserved_mem rmem = \u0026reserved_mem[i];\ndrivers/of/of_reserved_mem.c-199-\n--\ndrivers/of/of_reserved_mem.c=337=static int __init __rmem_cmp(const void a, const void b)\ndrivers/of/of_reserved_mem.c-338-{\ndrivers/of/of_reserved_mem.c:339:\tconst struct reserved_mem ra = a, rb = b;\ndrivers/of/of_reserved_mem.c-340-\n--\ndrivers/of/of_reserved_mem.c=360=static void __init __rmem_check_for_overlap(void)\n--\ndrivers/of/of_reserved_mem.c-366-\ndrivers/of/of_reserved_mem.c:367:\tsort(reserved_mem, reserved_mem_count, sizeof(reserved_mem[0]),\ndrivers/of/of_reserved_mem.c-368-\t __rmem_cmp, NULL);\ndrivers/of/of_reserved_mem.c-369-\tfor (i = 0; i \u003c reserved_mem_count - 1; i++) {\ndrivers/of/of_reserved_mem.c:370:\t\tstruct reserved_mem this, next;\ndrivers/of/of_reserved_mem.c-371-\ndrivers/of/of_reserved_mem.c:372:\t\tthis = \u0026reserved_mem[i];\ndrivers/of/of_reserved_mem.c:373:\t\tnext = \u0026reserved_mem[i + 1];\ndrivers/of/of_reserved_mem.c-374-\n--\ndrivers/of/of_reserved_mem.c-387-/\ndrivers/of/of_reserved_mem.c:388: fdt_scan_reserved_mem() - reserve and allocate memory occupied by\ndrivers/of/of_reserved_mem.c-389- * reserved memory regions.\n--\ndrivers/of/of_reserved_mem.c-392- * the \"reg\" property) reserved memory regions as reserved or no-map. Then\ndrivers/of/of_reserved_mem.c:393: * the reserved_mem array is allocated and a region specific init function\ndrivers/of/of_reserved_mem.c-394- * is called for each static region. Finally, memory for all dynamic regions\ndrivers/of/of_reserved_mem.c-395- * (defined by size \u0026 alignment) is allocated and their init functions are\ndrivers/of/of_reserved_mem.c:396: * called. Region information is stored in the reserved_mem array.\ndrivers/of/of_reserved_mem.c-397- /\ndrivers/of/of_reserved_mem.c:398:int __init fdt_scan_reserved_mem(void)\ndrivers/of/of_reserved_mem.c-399-{\ndrivers/of/of_reserved_mem.c:400:\tstruct reserved_mem array, map;\ndrivers/of/of_reserved_mem.c-401-\tbool bottom_up = memblock_bottom_up();\n--\ndrivers/of/of_reserved_mem.c-445-\tif (!array) {\ndrivers/of/of_reserved_mem.c:446:\t\tpr_err(\"Failed to allocate memory for reserved_mem array\\n\");\ndrivers/of/of_reserved_mem.c-447-\t\treturn -ENOMEM;\n--\ndrivers/of/of_reserved_mem.c-451-\tif (!map) {\ndrivers/of/of_reserved_mem.c:452:\t\tpr_err(\"Failed to map memory for reserved_mem array\\n\");\ndrivers/of/of_reserved_mem.c-453-\t\tmemblock_free(array, array_bytes);\n--\ndrivers/of/of_reserved_mem.c-457-\ndrivers/of/of_reserved_mem.c:458:\treserved_mem = map;\ndrivers/of/of_reserved_mem.c-459-\ttotal_reserved_mem_cnt = cnt;\n--\ndrivers/of/of_reserved_mem.c-488-\tearly_array_unmap(map, array_bytes);\ndrivers/of/of_reserved_mem.c:489:\treserved_mem = array;\ndrivers/of/of_reserved_mem.c-490-\treturn 0;\n--\ndrivers/of/of_reserved_mem.c=537=static int __init fdt_validate_reserved_mem_node(unsigned long node, phys_addr_t align)\n--\ndrivers/of/of_reserved_mem.c-556- * __reserved_mem_init_node() - initialize a reserved memory region\ndrivers/of/of_reserved_mem.c:557: * @rmem: reserved_mem structure to initialize\ndrivers/of/of_reserved_mem.c-558- * @node: FDT node describing the reserved memory region\n--\ndrivers/of/of_reserved_mem.c-561- * node_init callback for the compatible entry matching the node. On success,\ndrivers/of/of_reserved_mem.c:562: * the operations pointer is stored in the reserved_mem structure.\ndrivers/of/of_reserved_mem.c-563- \n--\ndrivers/of/of_reserved_mem.c-565- /\ndrivers/of/of_reserved_mem.c:566:static int __init __reserved_mem_init_node(struct reserved_mem rmem,\ndrivers/of/of_reserved_mem.c-567-\t\t\t\t\t unsigned long node)\n--\ndrivers/of/of_reserved_mem.c-599- reserved memory region and saves all region-specific data to the\ndrivers/of/of_reserved_mem.c:600: * reserved_mem array to allow of_reserved_mem_lookup() to find it.\ndrivers/of/of_reserved_mem.c-601- /\ndrivers/of/of_reserved_mem.c=602=static void __init fdt_init_reserved_mem_node(unsigned long node, const char uname,\n--\ndrivers/of/of_reserved_mem.c-607-\ndrivers/of/of_reserved_mem.c:608:\tstruct reserved_mem rmem = \u0026reserved_mem[reserved_mem_count];\ndrivers/of/of_reserved_mem.c-609-\n--\ndrivers/of/of_reserved_mem.c=647=struct rmem_assigned_device {\ndrivers/of/of_reserved_mem.c-648-\tstruct device dev;\ndrivers/of/of_reserved_mem.c:649:\tstruct reserved_mem rmem;\ndrivers/of/of_reserved_mem.c-650-\tstruct list_head list;\n--\ndrivers/of/of_reserved_mem.c=671=int of_reserved_mem_device_init_by_idx(struct device dev,\n--\ndrivers/of/of_reserved_mem.c-675-\tstruct device_node target;\ndrivers/of/of_reserved_mem.c:676:\tstruct reserved_mem rmem;\ndrivers/of/of_reserved_mem.c-677-\tint ret;\n--\ndrivers/of/of_reserved_mem.c=808=EXPORT_SYMBOL_GPL(devm_of_reserved_mem_device_init);\n--\ndrivers/of/of_reserved_mem.c-810-/*\ndrivers/of/of_reserved_mem.c:811: of_reserved_mem_lookup() - acquire reserved_mem from a device node\ndrivers/of/of_reserved_mem.c-812- * @np:\t\tnode pointer of the desired reserved-memory region\ndrivers/of/of_reserved_mem.c-813- \ndrivers/of/of_reserved_mem.c:814: This function allows drivers to acquire a reference to the reserved_mem\ndrivers/of/of_reserved_mem.c-815- * struct based on a device node handle.\ndrivers/of/of_reserved_mem.c-816- \ndrivers/of/of_reserved_mem.c:817: Returns a reserved_mem reference, or NULL on error.\ndrivers/of/of_reserved_mem.c-818- /\ndrivers/of/of_reserved_mem.c:819:struct reserved_mem of_reserved_mem_lookup(struct device_node np)\ndrivers/of/of_reserved_mem.c-820-{\n--\ndrivers/of/of_reserved_mem.c-828-\tfor (i = 0; i \u003c reserved_mem_count; i++)\ndrivers/of/of_reserved_mem.c:829:\t\tif (reserved_mem[i].name \u0026\u0026\ndrivers/of/of_reserved_mem.c:830:\t\t !strcmp(reserved_mem[i].name, name))\ndrivers/of/of_reserved_mem.c:831:\t\t\treturn \u0026reserved_mem[i];\ndrivers/of/of_reserved_mem.c-832-\n--\ndrivers/of/of_reserved_mem.c=849=int of_reserved_mem_region_to_resource(const struct device_node np,\n--\ndrivers/of/of_reserved_mem.c-851-{\ndrivers/of/of_reserved_mem.c:852:\tstruct reserved_mem *rmem;\ndrivers/of/of_reserved_mem.c-853-\n" }
25/2	2026/10/15 11:32	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 35508 output: 180 thoughts: 1167 Thoughts: Analysis of Code Changes and Fuzzing Worthiness Okay, let's break this down. My initial observation is that `of_reserved_mem_lookup` iterates through `reserved_mem[i]`. Right away, I see that on amd64, `fdt_scan_reserved_mem` is never called. This means `reserved_mem_count` is zero, and `reserved_mem` is NULL. I need to make sure I understand the full scope of these changes, though, so I'm going to look deeper. Did any non-__init functions get touched? Let's check the diff again. Looking at the `git diff`, I see several changes. `drivers/of/fdt.c` deleted the call to `fdt_scan_reserved_mem_late()` in `unflatten_device_tree()`. In `drivers/of/of_private.h`, I see the removal of `#define MAX_RESERVED_REGIONS 64` and the prototype for `fdt_scan_reserved_mem_late`. Now, looking at `drivers/of/of_reserved_mem.c` is where the meat of it lies. There are changes to the global variables, removal of `alloc_reserved_mem_array()` and the addition of `early_array_map()` and `early_array_unmap()`. There's a new `reserved_mem_reserve_failed` flag in `__reserved_mem_reserve_reg()`. The `fdt_scan_reserved_mem_late()` function has been removed and there are modifications to several `__init` functions. The key here is that all modified executable code is marked `__init`! That's the most critical observation. There's not a single non-`__init` function that was modified. What this means is that all of the functions affected by these changes (`unflatten_device_tree`, `fdt_scan_reserved_mem`, etc.) are only executed at boot time before the system transitions to userspace. The memory associated with these `__init` functions is freed after initialization. Syzkaller operates in userspace. It cannot reach `__init` code. Beyond that, `fdt_scan_reserved_mem()` itself isn't even called on amd64. It’s for architectures that pass DT reserved-memory nodes to `early_init_fdt_scan_reserved_mem()`. Now, let's review the instructions to be absolutely certain. The instructions specify returning WorthFuzzing=false if all modified code falls into certain categories. The relevant categories are: unreachable paths and code exclusive to other architectures. Here’s where we stand: 1. All modified functions are `__init` functions, executed only during early boot. Syzkaller cannot reach them. 2. The modified paths involving `fdt_scan_reserved_mem()` are exclusive to architectures that do use early Device Tree reserved memory scanning (ARM, etc.). amd64 doesn't use that path. Therefore, `WorthFuzzing` must be false. It's a clear fit for the negative criteria. Let's double-check again to ensure everything's covered: * WorthFuzzing: false * FocusSymbols: \[\] (as there are no relevant symbols) * EnableConfigs: \[\] (no config options need modification) * Reasoning: All modified executable functions (`unflatten_device_tree`, `fdt_scan_reserved_mem`, etc.) are `__init` and run exclusively during early boot. Their memory is freed, making them inaccessible to Syzkaller. Furthermore, the `fdt_scan_reserved_mem` path is only used on other architectures (ARM, etc.), and not on the target amd64 architecture. This is all perfectly clear and aligns perfectly with the negative criteria. Let's call `set-results`.
26/2	2026/10/15 11:32	tool	set-results	0m Args: { "EnableConfigs": [], "FocusSymbols": [], "Reasoning": "All modified functions (including fdt_scan_reserved_mem, __reserved_mem_init_reg, __reserved_mem_reserve_reg, __rmem_check_for_overlap, and unflatten_device_tree) are marked __init and execute strictly during early boot. Their memory is reclaimed at free_initmem() before user space initializes, making them unreachable by syzkaller. Furthermore, early device tree reserved memory scanning (fdt_scan_reserved_mem via early_init_fdt_scan_reserved_mem) is exclusive to architectures such as ARM, ARM64, PowerPC, and RISC-V, and is not called on the target architecture (amd64).", "WorthFuzzing": false } Results: { "EnableConfigs": null, "FocusSymbols": [], "Reasoning": "All modified functions (including fdt_scan_reserved_mem, __reserved_mem_init_reg, __reserved_mem_reserve_reg, __rmem_check_for_overlap, and unflatten_device_tree) are marked __init and execute strictly during early boot. Their memory is reclaimed at free_initmem() before user space initializes, making them unreachable by syzkaller. Furthermore, early device tree reserved memory scanning (fdt_scan_reserved_mem via early_init_fdt_scan_reserved_mem) is exclusive to architectures such as ARM, ARM64, PowerPC, and RISC-V, and is not called on the target architecture (amd64).", "WorthFuzzing": false }
27/1	2026/10/15 11:32	action	If	0m Args: { "WorthFuzzing": false } Results: null

LLM Calls Summary:
Total Calls	Total Tokens	Avg Tokens	Total Duration (Seconds)	Avg Duration (Seconds)

Tool Calls Summary:
Total Calls	Total Duration (Seconds)	Avg Duration (Seconds)