AI Trajectory

null

{
  "EnableConfigs": [
    "PTDUMP_DEBUGFS",
    "DEBUG_WX"
  ],
  "FocusSymbols": [
    "vmap_try_huge_pmd",
    "vmap_try_huge_pud",
    "vmap_try_huge_p4d",
    "cpa_collapse_large_pages",
    "ptdump_walk_pgd",
    "walk_page_range_debug"
  ],
  "Reasoning": "The patch modifies synchronization between page table dumping (ptdump), vmalloc huge page mappings, and x86 CPA (change page attribute) large page collapsing. It introduces new locking using mmap_read_lock/mmap_write_lock on init_mm. These are functional changes in core memory management and architecture-specific code that should be fuzzed to ensure no deadlocks or use-after-free issues occur.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 3b0191faac7a7a1cb397565bf13cae2d477a8f53\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Fri Jul 17 03:17:50 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h\nindex 5b374a6ab34a4e..50a195eda8ed22 100644\n--- a/arch/arm64/include/asm/ptdump.h\n+++ b/arch/arm64/include/asm/ptdump.h\n@@ -7,8 +7,6 @@\n \n #include \u003clinux/ptdump.h\u003e\n \n-DECLARE_STATIC_KEY_FALSE(arm64_ptdump_lock_key);\n-\n #ifdef CONFIG_PTDUMP\n \n #include \u003clinux/mm_types.h\u003e\ndiff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c\nindex a25d8beacc8310..bd52fca6e8720b 100644\n--- a/arch/arm64/mm/mmu.c\n+++ b/arch/arm64/mm/mmu.c\n@@ -49,8 +49,6 @@\n #define NO_CONT_MAPPINGS\tBIT(1)\n #define NO_EXEC_MAPPINGS\tBIT(2)\t/* assumes FEAT_HPDS is not used */\n \n-DEFINE_STATIC_KEY_FALSE(arm64_ptdump_lock_key);\n-\n u64 kimage_voffset __ro_after_init;\n EXPORT_SYMBOL(kimage_voffset);\n \n@@ -1864,8 +1862,7 @@ int pmd_clear_huge(pmd_t *pmdp)\n \treturn 1;\n }\n \n-static int __pmd_free_pte_page(pmd_t *pmdp, unsigned long addr,\n-\t\t\t       bool acquire_mmap_lock)\n+int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)\n {\n \tpte_t *table;\n \tpmd_t pmd;\n@@ -1877,25 +1874,13 @@ static int __pmd_free_pte_page(pmd_t *pmdp, unsigned long addr,\n \t\treturn 1;\n \t}\n \n-\t/* See comment in pud_free_pmd_page for static key logic */\n \ttable = pte_offset_kernel(pmdp, addr);\n \tpmd_clear(pmdp);\n \t__flush_tlb_kernel_pgtable(addr);\n-\tif (static_branch_unlikely(\u0026arm64_ptdump_lock_key) \u0026\u0026 acquire_mmap_lock) {\n-\t\tmmap_read_lock(\u0026init_mm);\n-\t\tmmap_read_unlock(\u0026init_mm);\n-\t}\n-\n \tpte_free_kernel(NULL, table);\n \treturn 1;\n }\n \n-int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)\n-{\n-\t/* If ptdump is walking the pagetables, acquire init_mm.mmap_lock */\n-\treturn __pmd_free_pte_page(pmdp, addr, /* acquire_mmap_lock = */ true);\n-}\n-\n int pud_free_pmd_page(pud_t *pudp, unsigned long addr)\n {\n \tpmd_t *table;\n@@ -1911,36 +1896,16 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)\n \t}\n \n \ttable = pmd_offset(pudp, addr);\n-\n-\t/*\n-\t * Our objective is to prevent ptdump from reading a PMD table which has\n-\t * been freed. In this race, if pud_free_pmd_page observes the key on\n-\t * (which got flipped by ptdump) then the mmap lock sequence here will,\n-\t * as a result of the mmap write lock/unlock sequence in ptdump, give\n-\t * us the correct synchronization. If not, this means that ptdump has\n-\t * yet not started walking the pagetables - the sequence of barriers\n-\t * issued by __flush_tlb_kernel_pgtable() guarantees that ptdump will\n-\t * observe an empty PUD.\n-\t */\n-\tpud_clear(pudp);\n-\t__flush_tlb_kernel_pgtable(addr);\n-\tif (static_branch_unlikely(\u0026arm64_ptdump_lock_key)) {\n-\t\tmmap_read_lock(\u0026init_mm);\n-\t\tmmap_read_unlock(\u0026init_mm);\n-\t}\n-\n \tpmdp = table;\n \tnext = addr;\n \tend = addr + PUD_SIZE;\n \tdo {\n \t\tif (pmd_present(pmdp_get(pmdp)))\n-\t\t\t/*\n-\t\t\t * PMD has been isolated, so ptdump won't see it. No\n-\t\t\t * need to acquire init_mm.mmap_lock.\n-\t\t\t */\n-\t\t\t__pmd_free_pte_page(pmdp, next, /* acquire_mmap_lock = */ false);\n+\t\t\tpmd_free_pte_page(pmdp, next);\n \t} while (pmdp++, next += PMD_SIZE, next != end);\n \n+\tpud_clear(pudp);\n+\t__flush_tlb_kernel_pgtable(addr);\n \tpmd_free(NULL, table);\n \treturn 1;\n }\ndiff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c\nindex 1c20144700d7d7..5a76c59b5ada55 100644\n--- a/arch/arm64/mm/ptdump.c\n+++ b/arch/arm64/mm/ptdump.c\n@@ -283,13 +283,6 @@ void note_page_flush(struct ptdump_state *pt_st)\n \tnote_page(pt_st, 0, -1, pte_val(pte_zero));\n }\n \n-static void arm64_ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm)\n-{\n-\tstatic_branch_inc(\u0026arm64_ptdump_lock_key);\n-\tptdump_walk_pgd(st, mm, NULL);\n-\tstatic_branch_dec(\u0026arm64_ptdump_lock_key);\n-}\n-\n void ptdump_walk(struct seq_file *s, struct ptdump_info *info)\n {\n \tunsigned long end = ~0UL;\n@@ -318,7 +311,7 @@ void ptdump_walk(struct seq_file *s, struct ptdump_info *info)\n \t\t}\n \t};\n \n-\tarm64_ptdump_walk_pgd(\u0026st.ptdump, info-\u003emm);\n+\tptdump_walk_pgd(\u0026st.ptdump, info-\u003emm, NULL);\n }\n \n static void __init ptdump_initialize(void)\n@@ -360,7 +353,7 @@ bool ptdump_check_wx(void)\n \t\t}\n \t};\n \n-\tarm64_ptdump_walk_pgd(\u0026st.ptdump, \u0026init_mm);\n+\tptdump_walk_pgd(\u0026st.ptdump, \u0026init_mm, NULL);\n \n \tif (st.wx_pages || st.uxn_pages) {\n \t\tpr_warn(\"Checked W+X mappings: FAILED, %lu W+X pages found, %lu non-UXN pages found\\n\",\ndiff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c\nindex d023a40a1e0345..d1e63f7d267ff3 100644\n--- a/arch/x86/mm/pat/set_memory.c\n+++ b/arch/x86/mm/pat/set_memory.c\n@@ -22,6 +22,7 @@\n #include \u003clinux/cc_platform.h\u003e\n #include \u003clinux/set_memory.h\u003e\n #include \u003clinux/memregion.h\u003e\n+#include \u003clinux/cleanup.h\u003e\n \n #include \u003casm/e820/api.h\u003e\n #include \u003casm/processor.h\u003e\n@@ -410,7 +411,7 @@ static void __cpa_flush_tlb(void *data)\n \n static int collapse_large_pages(unsigned long addr, struct list_head *pgtables);\n \n-static void cpa_collapse_large_pages(struct cpa_data *cpa)\n+static void __cpa_collapse_large_pages(struct cpa_data *cpa)\n {\n \tunsigned long start, addr, end;\n \tstruct ptdesc *ptdesc, *tmp;\n@@ -442,6 +443,18 @@ static void cpa_collapse_large_pages(struct cpa_data *cpa)\n \t}\n }\n \n+static void cpa_collapse_large_pages(struct cpa_data *cpa)\n+{\n+\t/*\n+\t * Take the mmap write lock on init_mm to:\n+\t * - Avoid a use-after-free if raced by ptdump (which takes its own\n+\t *   write lock on init_mm).\n+\t * - Serialise concurrent CPA walkers.\n+\t */\n+\tscoped_guard(mmap_write_lock, \u0026init_mm)\n+\t\t__cpa_collapse_large_pages(cpa);\n+}\n+\n static void cpa_flush(struct cpa_data *cpa, int cache)\n {\n \tunsigned int i;\ndiff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h\nindex 04b8f61ece5d8e..047f5f5e2c3475 100644\n--- a/include/linux/mmap_lock.h\n+++ b/include/linux/mmap_lock.h\n@@ -621,6 +621,9 @@ static inline void mmap_read_unlock(struct mm_struct *mm)\n \n DEFINE_GUARD(mmap_read_lock, struct mm_struct *,\n \t     mmap_read_lock(_T), mmap_read_unlock(_T))\n+DEFINE_GUARD(mmap_write_lock, struct mm_struct *,\n+\t     mmap_write_lock(_T), mmap_write_unlock(_T))\n+DEFINE_GUARD_COND(mmap_read_lock, _try, mmap_read_trylock(_T))\n \n static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)\n {\ndiff --git a/mm/pagewalk.c b/mm/pagewalk.c\nindex 3ae2586ff45b44..5d87c632a25507 100644\n--- a/mm/pagewalk.c\n+++ b/mm/pagewalk.c\n@@ -678,6 +678,8 @@ int walk_kernel_page_table_range_lockless(unsigned long start, unsigned long end\n  * will also not lock the PTEs for the pte_entry() callback.\n  *\n  * This is for debugging purposes ONLY.\n+ *\n+ * The mmap write lock must be held.\n  */\n int walk_page_range_debug(struct mm_struct *mm, unsigned long start,\n \t\t\t  unsigned long end, const struct mm_walk_ops *ops,\n@@ -691,24 +693,28 @@ int walk_page_range_debug(struct mm_struct *mm, unsigned long start,\n \t\t.no_vma\t\t= true\n \t};\n \n-\t/* For convenience, we allow traversal of kernel mappings. */\n-\tif (mm == \u0026init_mm)\n-\t\treturn walk_kernel_page_table_range(start, end, ops,\n-\t\t\t\t\t\t    pgd, private);\n-\tif (start \u003e= end || !walk.mm)\n-\t\treturn -EINVAL;\n-\tif (!check_ops_safe(ops))\n-\t\treturn -EINVAL;\n-\n \t/*\n-\t * The mmap lock protects the page walker from changes to the page\n-\t * tables during the walk.  However a read lock is insufficient to\n-\t * protect those areas which don't have a VMA as munmap() detaches\n-\t * the VMAs before downgrading to a read lock and actually tearing\n-\t * down PTEs/page tables. In which case, the mmap write lock should\n-\t * be held.\n+\t * When walking userland page tables, an mmap write lock must be held to\n+\t * account for munmap() downgrading to an mmap read lock when tearing\n+\t * down page tables.\n+\t *\n+\t * When walking kernel page tables, an mmap write lock must also be held\n+\t * to account for page table freeing on vmap huge page mapping.\n \t */\n \tmmap_assert_write_locked(mm);\n+\t/*\n+\t * x86, arm64 ptdump allow walks of efi mm's and x86 ptdump allows walks\n+\t * of arbitrary mm's.\n+\t *\n+\t * However, they both must also hold the init_mm lock to account for\n+\t * concurrent kernel page table freeing.\n+\t */\n+\tmmap_assert_write_locked(\u0026init_mm);\n+\n+\tif (start \u003e= end)\n+\t\treturn -EINVAL;\n+\tif (!check_ops_safe(ops))\n+\t\treturn -EINVAL;\n \n \treturn walk_pgd_range(start, end, \u0026walk);\n }\ndiff --git a/mm/ptdump.c b/mm/ptdump.c\nindex 973020000096cf..5851096e6f656c 100644\n--- a/mm/ptdump.c\n+++ b/mm/ptdump.c\n@@ -178,11 +178,18 @@ void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)\n \n \tget_online_mems();\n \tmmap_write_lock(mm);\n+\t/* To stabilise kernel page tables we must hold the init_mm lock too. */\n+\tif (mm != \u0026init_mm)\n+\t\tmmap_write_lock_nested(\u0026init_mm, SINGLE_DEPTH_NESTING);\n+\n \twhile (range-\u003estart != range-\u003eend) {\n \t\twalk_page_range_debug(mm, range-\u003estart, range-\u003eend,\n \t\t\t\t      \u0026ptdump_ops, pgd, st);\n \t\trange++;\n \t}\n+\n+\tif (mm != \u0026init_mm)\n+\t\tmmap_write_unlock(\u0026init_mm);\n \tmmap_write_unlock(mm);\n \tput_online_mems();\n \ndiff --git a/mm/vmalloc.c b/mm/vmalloc.c\nindex 1afca3568b9b65..f4fa227a8d7f04 100644\n--- a/mm/vmalloc.c\n+++ b/mm/vmalloc.c\n@@ -43,6 +43,7 @@\n #include \u003casm/tlbflush.h\u003e\n #include \u003casm/shmparam.h\u003e\n #include \u003clinux/page_owner.h\u003e\n+#include \u003clinux/cleanup.h\u003e\n \n #define CREATE_TRACE_POINTS\n #include \u003ctrace/events/vmalloc.h\u003e\n@@ -158,10 +159,21 @@ static int vmap_try_huge_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,\n \tif (!IS_ALIGNED(phys_addr, PMD_SIZE))\n \t\treturn 0;\n \n-\tif (pmd_present(*pmd) \u0026\u0026 !pmd_free_pte_page(pmd, addr))\n-\t\treturn 0;\n+\tif (!pmd_present(*pmd))\n+\t\treturn pmd_set_huge(pmd, phys_addr, prot);\n \n-\treturn pmd_set_huge(pmd, phys_addr, prot);\n+\t/*\n+\t * Acquire the mmap read lock to exclude ptdump, which walks\n+\t * kernel page tables it does not own under the mmap write lock.\n+\t *\n+\t * Concurrent read lock holders are safe: each exclusively owns\n+\t * the range it operates on and cannot reach this page table.\n+\t */\n+\tscoped_cond_guard(mmap_read_lock_try, return 0, \u0026init_mm) {\n+\t\tif (!pmd_free_pte_page(pmd, addr))\n+\t\t\treturn 0;\n+\t\treturn pmd_set_huge(pmd, phys_addr, prot);\n+\t}\n }\n \n static int vmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,\n@@ -210,10 +222,15 @@ static int vmap_try_huge_pud(pud_t *pud, unsigned long addr, unsigned long end,\n \tif (!IS_ALIGNED(phys_addr, PUD_SIZE))\n \t\treturn 0;\n \n-\tif (pud_present(*pud) \u0026\u0026 !pud_free_pmd_page(pud, addr))\n-\t\treturn 0;\n+\tif (!pud_present(*pud))\n+\t\treturn pud_set_huge(pud, phys_addr, prot);\n \n-\treturn pud_set_huge(pud, phys_addr, prot);\n+\t/* See comment in vmap_try_huge_pmd(). */\n+\tscoped_cond_guard(mmap_read_lock_try, return 0, \u0026init_mm) {\n+\t\tif (!pud_free_pmd_page(pud, addr))\n+\t\t\treturn 0;\n+\t\treturn pud_set_huge(pud, phys_addr, prot);\n+\t}\n }\n \n static int vmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,\n@@ -262,10 +279,15 @@ static int vmap_try_huge_p4d(p4d_t *p4d, unsigned long addr, unsigned long end,\n \tif (!IS_ALIGNED(phys_addr, P4D_SIZE))\n \t\treturn 0;\n \n-\tif (p4d_present(*p4d) \u0026\u0026 !p4d_free_pud_page(p4d, addr))\n-\t\treturn 0;\n+\tif (!p4d_present(*p4d))\n+\t\treturn p4d_set_huge(p4d, phys_addr, prot);\n \n-\treturn p4d_set_huge(p4d, phys_addr, prot);\n+\t/* See comment in vmap_try_huge_pmd(). */\n+\tscoped_cond_guard(mmap_read_lock_try, return 0, \u0026init_mm) {\n+\t\tif (!p4d_free_pud_page(p4d, addr))\n+\t\t\treturn 0;\n+\t\treturn p4d_set_huge(p4d, phys_addr, prot);\n+\t}\n }\n \n static int vmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,\n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": [
    "PTDUMP_DEBUGFS",
    "DEBUG_WX"
  ],
  "FocusSymbols": [
    "vmap_try_huge_pmd",
    "vmap_try_huge_pud",
    "vmap_try_huge_p4d",
    "cpa_collapse_large_pages",
    "ptdump_walk_pgd",
    "walk_page_range_debug"
  ],
  "Reasoning": "The patch modifies synchronization between page table dumping (ptdump), vmalloc huge page mappings, and x86 CPA (change page attribute) large page collapsing. It introduces new locking using mmap_read_lock/mmap_write_lock on init_mm. These are functional changes in core memory management and architecture-specific code that should be fuzzed to ensure no deadlocks or use-after-free issues occur.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. List them in the EnableConfigs output array,
   and DO NOT add a '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.

For your convenience, here is the diff of the changes:
commit 3b0191faac7a7a1cb397565bf13cae2d477a8f53
Author: syz-cluster <triage@syzkaller.com>
Date:   Fri Jul 17 03:17:50 2026 +0000

    syz-cluster: applied patch under review

diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h
index 5b374a6ab34a4e..50a195eda8ed22 100644
--- a/arch/arm64/include/asm/ptdump.h
+++ b/arch/arm64/include/asm/ptdump.h
@@ -7,8 +7,6 @@
 
 #include <linux/ptdump.h>
 
-DECLARE_STATIC_KEY_FALSE(arm64_ptdump_lock_key);
-
 #ifdef CONFIG_PTDUMP
 
 #include <linux/mm_types.h>
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index a25d8beacc8310..bd52fca6e8720b 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -49,8 +49,6 @@
 #define NO_CONT_MAPPINGS	BIT(1)
 #define NO_EXEC_MAPPINGS	BIT(2)	/* assumes FEAT_HPDS is not used */
 
-DEFINE_STATIC_KEY_FALSE(arm64_ptdump_lock_key);
-
 u64 kimage_voffset __ro_after_init;
 EXPORT_SYMBOL(kimage_voffset);
 
@@ -1864,8 +1862,7 @@ int pmd_clear_huge(pmd_t *pmdp)
 	return 1;
 }
 
-static int __pmd_free_pte_page(pmd_t *pmdp, unsigned long addr,
-			       bool acquire_mmap_lock)
+int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
 {
 	pte_t *table;
 	pmd_t pmd;
@@ -1877,25 +1874,13 @@ static int __pmd_free_pte_page(pmd_t *pmdp, unsigned long addr,
 		return 1;
 	}
 
-	/* See comment in pud_free_pmd_page for static key logic */
 	table = pte_offset_kernel(pmdp, addr);
 	pmd_clear(pmdp);
 	__flush_tlb_kernel_pgtable(addr);
-	if (static_branch_unlikely(&arm64_ptdump_lock_key) && acquire_mmap_lock) {
-		mmap_read_lock(&init_mm);
-		mmap_read_unlock(&init_mm);
-	}
-
 	pte_free_kernel(NULL, table);
 	return 1;
 }
 
-int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
-{
-	/* If ptdump is walking the pagetables, acquire init_mm.mmap_lock */
-	return __pmd_free_pte_page(pmdp, addr, /* acquire_mmap_lock = */ true);
-}
-
 int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
 {
 	pmd_t *table;
@@ -1911,36 +1896,16 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
 	}
 
 	table = pmd_offset(pudp, addr);
-
-	/*
-	 * Our objective is to prevent ptdump from reading a PMD table which has
-	 * been freed. In this race, if pud_free_pmd_page observes the key on
-	 * (which got flipped by ptdump) then the mmap lock sequence here will,
-	 * as a result of the mmap write lock/unlock sequence in ptdump, give
-	 * us the correct synchronization. If not, this means that ptdump has
-	 * yet not started walking the pagetables - the sequence of barriers
-	 * issued by __flush_tlb_kernel_pgtable() guarantees that ptdump will
-	 * observe an empty PUD.
-	 */
-	pud_clear(pudp);
-	__flush_tlb_kernel_pgtable(addr);
-	if (static_branch_unlikely(&arm64_ptdump_lock_key)) {
-		mmap_read_lock(&init_mm);
-		mmap_read_unlock(&init_mm);
-	}
-
 	pmdp = table;
 	next = addr;
 	end = addr + PUD_SIZE;
 	do {
 		if (pmd_present(pmdp_get(pmdp)))
-			/*
-			 * PMD has been isolated, so ptdump won't see it. No
-			 * need to acquire init_mm.mmap_lock.
-			 */
-			__pmd_free_pte_page(pmdp, next, /* acquire_mmap_lock = */ false);
+			pmd_free_pte_page(pmdp, next);
 	} while (pmdp++, next += PMD_SIZE, next != end);
 
+	pud_clear(pudp);
+	__flush_tlb_kernel_pgtable(addr);
 	pmd_free(NULL, table);
 	return 1;
 }
diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
index 1c20144700d7d7..5a76c59b5ada55 100644
--- a/arch/arm64/mm/ptdump.c
+++ b/arch/arm64/mm/ptdump.c
@@ -283,13 +283,6 @@ void note_page_flush(struct ptdump_state *pt_st)
 	note_page(pt_st, 0, -1, pte_val(pte_zero));
 }
 
-static void arm64_ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm)
-{
-	static_branch_inc(&arm64_ptdump_lock_key);
-	ptdump_walk_pgd(st, mm, NULL);
-	static_branch_dec(&arm64_ptdump_lock_key);
-}
-
 void ptdump_walk(struct seq_file *s, struct ptdump_info *info)
 {
 	unsigned long end = ~0UL;
@@ -318,7 +311,7 @@ void ptdump_walk(struct seq_file *s, struct ptdump_info *info)
 		}
 	};
 
-	arm64_ptdump_walk_pgd(&st.ptdump, info->mm);
+	ptdump_walk_pgd(&st.ptdump, info->mm, NULL);
 }
 
 static void __init ptdump_initialize(void)
@@ -360,7 +353,7 @@ bool ptdump_check_wx(void)
 		}
 	};
 
-	arm64_ptdump_walk_pgd(&st.ptdump, &init_mm);
+	ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 
 	if (st.wx_pages || st.uxn_pages) {
 		pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found, %lu non-UXN pages found\n",
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index d023a40a1e0345..d1e63f7d267ff3 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -22,6 +22,7 @@
 #include <linux/cc_platform.h>
 #include <linux/set_memory.h>
 #include <linux/memregion.h>
+#include <linux/cleanup.h>
 
 #include <asm/e820/api.h>
 #include <asm/processor.h>
@@ -410,7 +411,7 @@ static void __cpa_flush_tlb(void *data)
 
 static int collapse_large_pages(unsigned long addr, struct list_head *pgtables);
 
-static void cpa_collapse_large_pages(struct cpa_data *cpa)
+static void __cpa_collapse_large_pages(struct cpa_data *cpa)
 {
 	unsigned long start, addr, end;
 	struct ptdesc *ptdesc, *tmp;
@@ -442,6 +443,18 @@ static void cpa_collapse_large_pages(struct cpa_data *cpa)
 	}
 }
 
+static void cpa_collapse_large_pages(struct cpa_data *cpa)
+{
+	/*
+	 * Take the mmap write lock on init_mm to:
+	 * - Avoid a use-after-free if raced by ptdump (which takes its own
+	 *   write lock on init_mm).
+	 * - Serialise concurrent CPA walkers.
+	 */
+	scoped_guard(mmap_write_lock, &init_mm)
+		__cpa_collapse_large_pages(cpa);
+}
+
 static void cpa_flush(struct cpa_data *cpa, int cache)
 {
 	unsigned int i;
diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 04b8f61ece5d8e..047f5f5e2c3475 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -621,6 +621,9 @@ static inline void mmap_read_unlock(struct mm_struct *mm)
 
 DEFINE_GUARD(mmap_read_lock, struct mm_struct *,
 	     mmap_read_lock(_T), mmap_read_unlock(_T))
+DEFINE_GUARD(mmap_write_lock, struct mm_struct *,
+	     mmap_write_lock(_T), mmap_write_unlock(_T))
+DEFINE_GUARD_COND(mmap_read_lock, _try, mmap_read_trylock(_T))
 
 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
 {
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 3ae2586ff45b44..5d87c632a25507 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -678,6 +678,8 @@ int walk_kernel_page_table_range_lockless(unsigned long start, unsigned long end
  * will also not lock the PTEs for the pte_entry() callback.
  *
  * This is for debugging purposes ONLY.
+ *
+ * The mmap write lock must be held.
  */
 int walk_page_range_debug(struct mm_struct *mm, unsigned long start,
 			  unsigned long end, const struct mm_walk_ops *ops,
@@ -691,24 +693,28 @@ int walk_page_range_debug(struct mm_struct *mm, unsigned long start,
 		.no_vma		= true
 	};
 
-	/* For convenience, we allow traversal of kernel mappings. */
-	if (mm == &init_mm)
-		return walk_kernel_page_table_range(start, end, ops,
-						    pgd, private);
-	if (start >= end || !walk.mm)
-		return -EINVAL;
-	if (!check_ops_safe(ops))
-		return -EINVAL;
-
 	/*
-	 * The mmap lock protects the page walker from changes to the page
-	 * tables during the walk.  However a read lock is insufficient to
-	 * protect those areas which don't have a VMA as munmap() detaches
-	 * the VMAs before downgrading to a read lock and actually tearing
-	 * down PTEs/page tables. In which case, the mmap write lock should
-	 * be held.
+	 * When walking userland page tables, an mmap write lock must be held to
+	 * account for munmap() downgrading to an mmap read lock when tearing
+	 * down page tables.
+	 *
+	 * When walking kernel page tables, an mmap write lock must also be held
+	 * to account for page table freeing on vmap huge page mapping.
 	 */
 	mmap_assert_write_locked(mm);
+	/*
+	 * x86, arm64 ptdump allow walks of efi mm's and x86 ptdump allows walks
+	 * of arbitrary mm's.
+	 *
+	 * However, they both must also hold the init_mm lock to account for
+	 * concurrent kernel page table freeing.
+	 */
+	mmap_assert_write_locked(&init_mm);
+
+	if (start >= end)
+		return -EINVAL;
+	if (!check_ops_safe(ops))
+		return -EINVAL;
 
 	return walk_pgd_range(start, end, &walk);
 }
diff --git a/mm/ptdump.c b/mm/ptdump.c
index 973020000096cf..5851096e6f656c 100644
--- a/mm/ptdump.c
+++ b/mm/ptdump.c
@@ -178,11 +178,18 @@ void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
 
 	get_online_mems();
 	mmap_write_lock(mm);
+	/* To stabilise kernel page tables we must hold the init_mm lock too. */
+	if (mm != &init_mm)
+		mmap_write_lock_nested(&init_mm, SINGLE_DEPTH_NESTING);
+
 	while (range->start != range->end) {
 		walk_page_range_debug(mm, range->start, range->end,
 				      &ptdump_ops, pgd, st);
 		range++;
 	}
+
+	if (mm != &init_mm)
+		mmap_write_unlock(&init_mm);
 	mmap_write_unlock(mm);
 	put_online_mems();
 
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 1afca3568b9b65..f4fa227a8d7f04 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -43,6 +43,7 @@
 #include <asm/tlbflush.h>
 #include <asm/shmparam.h>
 #include <linux/page_owner.h>
+#include <linux/cleanup.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/vmalloc.h>
@@ -158,10 +159,21 @@ static int vmap_try_huge_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,
 	if (!IS_ALIGNED(phys_addr, PMD_SIZE))
 		return 0;
 
-	if (pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr))
-		return 0;
+	if (!pmd_present(*pmd))
+		return pmd_set_huge(pmd, phys_addr, prot);
 
-	return pmd_set_huge(pmd, phys_addr, prot);
+	/*
+	 * Acquire the mmap read lock to exclude ptdump, which walks
+	 * kernel page tables it does not own under the mmap write lock.
+	 *
+	 * Concurrent read lock holders are safe: each exclusively owns
+	 * the range it operates on and cannot reach this page table.
+	 */
+	scoped_cond_guard(mmap_read_lock_try, return 0, &init_mm) {
+		if (!pmd_free_pte_page(pmd, addr))
+			return 0;
+		return pmd_set_huge(pmd, phys_addr, prot);
+	}
 }
 
 static int vmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
@@ -210,10 +222,15 @@ static int vmap_try_huge_pud(pud_t *pud, unsigned long addr, unsigned long end,
 	if (!IS_ALIGNED(phys_addr, PUD_SIZE))
 		return 0;
 
-	if (pud_present(*pud) && !pud_free_pmd_page(pud, addr))
-		return 0;
+	if (!pud_present(*pud))
+		return pud_set_huge(pud, phys_addr, prot);
 
-	return pud_set_huge(pud, phys_addr, prot);
+	/* See comment in vmap_try_huge_pmd(). */
+	scoped_cond_guard(mmap_read_lock_try, return 0, &init_mm) {
+		if (!pud_free_pmd_page(pud, addr))
+			return 0;
+		return pud_set_huge(pud, phys_addr, prot);
+	}
 }
 
 static int vmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
@@ -262,10 +279,15 @@ static int vmap_try_huge_p4d(p4d_t *p4d, unsigned long addr, unsigned long end,
 	if (!IS_ALIGNED(phys_addr, P4D_SIZE))
 		return 0;
 
-	if (p4d_present(*p4d) && !p4d_free_pud_page(p4d, addr))
-		return 0;
+	if (!p4d_present(*p4d))
+		return p4d_set_huge(p4d, phys_addr, prot);
 
-	return p4d_set_huge(p4d, phys_addr, prot);
+	/* See comment in vmap_try_huge_pmd(). */
+	scoped_cond_guard(mmap_read_lock_try, return 0, &init_mm) {
+		if (!p4d_free_pud_page(p4d, addr))
+			return 0;
+		return p4d_set_huge(p4d, phys_addr, prot);
+	}
 }
 
 static int vmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,

gemini-3.1-pro-preview

null

null

							input: 6492
							output: 21
							thoughts: 437
						

**Analyzing a Core Kernel Memory Management Patch**

Okay, so I've got this patch in front of me that's tweaking some pretty fundamental kernel memory management stuff, specifically related to page table dumping and vmalloc huge page mappings. It's touching on both x86 and arm64 architectures, which immediately flags it as something that needs a thorough look-over. I see they're removing the `arm64_ptdump_lock_key` and revising the synchronization in functions like `pmd_free_pte_page`, `pud_free_pmd_page`, and `ptdump_walk_pgd`. That synchronization logic change always warrants extra scrutiny.

They're using `mmap_write_lock(&init_mm)` in `ptdump_walk_pgd` and `cpa_collapse_large_pages`, and they've introduced this `scoped_cond_guard` with `mmap_read_lock_try` in several `vmap_try_huge_*` functions. This means concurrency is now handled differently in these critical vmalloc areas. These are all core changes, directly impacting memory management and vmalloc, so I'm already thinking this is high priority for testing. Given the breadth of the impact, fuzzing is an absolute must here.

Let's quickly identify the key functions this patch affects. I'm focusing on: `vmap_try_huge_pmd`, `vmap_try_huge_pud`, `vmap_try_huge_p4d`, `ptdump_walk_pgd`, `cpa_collapse_large_pages`, and `walk_page_range_debug`. I need to understand how these functions are supposed to work in both lock and lockless scenarios and what sort of concurrency issues are expected.

Now, let's identify the required configurations to trigger the relevant code paths. Clearly, `CONFIG_PTDUMP_CORE` is involved because we're looking at code in `mm/ptdump.c`. To get this working from userspace, I'll need `CONFIG_PTDUMP_DEBUGFS`. Plus, `CONFIG_DEBUG_WX` will be useful since it triggers ptdump at boot. And of course, `CONFIG_HAVE_ARCH_HUGE_VMAP` is essential to enable the vmap huge page logic that's being modified. Now I should quickly do a quick code search to verify these configurations are set in the relevant code. I need to make sure I understand the full configuration dependencies.

{
  "Expression": "ptdump_walk_pgd"
}

{
  "Output": "arch/arm/include/asm/ptdump.h=16=struct ptdump_info {\n--\narch/arm/include/asm/ptdump.h-21-\narch/arm/include/asm/ptdump.h:22:void ptdump_walk_pgd(struct seq_file *s, struct ptdump_info *info);\narch/arm/include/asm/ptdump.h-23-#ifdef CONFIG_ARM_PTDUMP_DEBUGFS\n--\narch/arm/mm/dump.c=398=static void walk_pgd(struct pg_state *st, struct mm_struct *mm,\n--\narch/arm/mm/dump.c-414-\narch/arm/mm/dump.c:415:void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)\narch/arm/mm/dump.c-416-{\n--\narch/arm/mm/ptdump_debugfs.c=7=static int ptdump_show(struct seq_file *m, void *v)\n--\narch/arm/mm/ptdump_debugfs.c-10-\narch/arm/mm/ptdump_debugfs.c:11:\tptdump_walk_pgd(m, info);\narch/arm/mm/ptdump_debugfs.c-12-\treturn 0;\n--\narch/arm64/mm/ptdump.c=286=void ptdump_walk(struct seq_file *s, struct ptdump_info *info)\n--\narch/arm64/mm/ptdump.c-313-\narch/arm64/mm/ptdump.c:314:\tptdump_walk_pgd(\u0026st.ptdump, info-\u003emm, NULL);\narch/arm64/mm/ptdump.c-315-}\n--\narch/arm64/mm/ptdump.c=331=bool ptdump_check_wx(void)\n--\narch/arm64/mm/ptdump.c-355-\narch/arm64/mm/ptdump.c:356:\tptdump_walk_pgd(\u0026st.ptdump, \u0026init_mm, NULL);\narch/arm64/mm/ptdump.c-357-\n--\narch/powerpc/mm/ptdump/ptdump.c=334=static int ptdump_show(struct seq_file *m, void *v)\n--\narch/powerpc/mm/ptdump/ptdump.c-351-\t/* Traverse kernel page tables */\narch/powerpc/mm/ptdump/ptdump.c:352:\tptdump_walk_pgd(\u0026st.ptdump, \u0026init_mm, NULL);\narch/powerpc/mm/ptdump/ptdump.c-353-\treturn 0;\n--\narch/powerpc/mm/ptdump/ptdump.c=368=bool ptdump_check_wx(void)\n--\narch/powerpc/mm/ptdump/ptdump.c-391-\narch/powerpc/mm/ptdump/ptdump.c:392:\tptdump_walk_pgd(\u0026st.ptdump, \u0026init_mm, NULL);\narch/powerpc/mm/ptdump/ptdump.c-393-\n--\narch/riscv/mm/ptdump.c=353=static void ptdump_walk(struct seq_file *s, struct ptd_mm_info *pinfo)\n--\narch/riscv/mm/ptdump.c-372-\narch/riscv/mm/ptdump.c:373:\tptdump_walk_pgd(\u0026st.ptdump, pinfo-\u003emm, NULL);\narch/riscv/mm/ptdump.c-374-}\n--\narch/riscv/mm/ptdump.c=376=bool ptdump_check_wx(void)\n--\narch/riscv/mm/ptdump.c-399-\narch/riscv/mm/ptdump.c:400:\tptdump_walk_pgd(\u0026st.ptdump, \u0026init_mm, NULL);\narch/riscv/mm/ptdump.c-401-\n--\narch/s390/mm/dump_pagetables.c=182=bool ptdump_check_wx(void)\n--\narch/s390/mm/dump_pagetables.c-210-\t\treturn true;\narch/s390/mm/dump_pagetables.c:211:\tptdump_walk_pgd(\u0026st.ptdump, \u0026init_mm, NULL);\narch/s390/mm/dump_pagetables.c-212-\tif (st.wx_pages) {\n--\narch/s390/mm/dump_pagetables.c=226=static int ptdump_show(struct seq_file *m, void *v)\n--\narch/s390/mm/dump_pagetables.c-250-\tmutex_lock(\u0026cpa_mutex);\narch/s390/mm/dump_pagetables.c:251:\tptdump_walk_pgd(\u0026st.ptdump, \u0026init_mm, NULL);\narch/s390/mm/dump_pagetables.c-252-\tmutex_unlock(\u0026cpa_mutex);\n--\narch/x86/include/asm/pgtable.h=30=struct seq_file;\narch/x86/include/asm/pgtable.h:31:void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm);\narch/x86/include/asm/pgtable.h:32:void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,\narch/x86/include/asm/pgtable.h-33-\t\t\t\t   bool user);\narch/x86/include/asm/pgtable.h:34:bool ptdump_walk_pgd_level_checkwx(void);\narch/x86/include/asm/pgtable.h:35:#define ptdump_check_wx ptdump_walk_pgd_level_checkwx\narch/x86/include/asm/pgtable.h-36-void ptdump_walk_user_pgd_level_checkwx(void);\n--\narch/x86/mm/debug_pagetables.c=8=static int ptdump_show(struct seq_file *m, void *v)\narch/x86/mm/debug_pagetables.c-9-{\narch/x86/mm/debug_pagetables.c:10:\tptdump_walk_pgd_level_debugfs(m, \u0026init_mm, false);\narch/x86/mm/debug_pagetables.c-11-\treturn 0;\n--\narch/x86/mm/debug_pagetables.c=16=static int ptdump_curknl_show(struct seq_file *m, void *v)\n--\narch/x86/mm/debug_pagetables.c-18-\tif (current-\u003emm-\u003epgd)\narch/x86/mm/debug_pagetables.c:19:\t\tptdump_walk_pgd_level_debugfs(m, current-\u003emm, false);\narch/x86/mm/debug_pagetables.c-20-\treturn 0;\n--\narch/x86/mm/debug_pagetables.c=26=static int ptdump_curusr_show(struct seq_file *m, void *v)\n--\narch/x86/mm/debug_pagetables.c-28-\tif (current-\u003emm-\u003epgd)\narch/x86/mm/debug_pagetables.c:29:\t\tptdump_walk_pgd_level_debugfs(m, current-\u003emm, true);\narch/x86/mm/debug_pagetables.c-30-\treturn 0;\n--\narch/x86/mm/debug_pagetables.c=37=static int ptdump_efi_show(struct seq_file *m, void *v)\n--\narch/x86/mm/debug_pagetables.c-39-\tif (efi_mm.pgd)\narch/x86/mm/debug_pagetables.c:40:\t\tptdump_walk_pgd_level_debugfs(m, \u0026efi_mm, false);\narch/x86/mm/debug_pagetables.c-41-\treturn 0;\n--\narch/x86/mm/dump_pagetables.c=416=static void note_page_flush(struct ptdump_state *pt_st)\n--\narch/x86/mm/dump_pagetables.c-422-\narch/x86/mm/dump_pagetables.c:423:bool ptdump_walk_pgd_level_core(struct seq_file *m,\narch/x86/mm/dump_pagetables.c-424-\t\t\t\tstruct mm_struct *mm, pgd_t *pgd,\n--\narch/x86/mm/dump_pagetables.c-457-\narch/x86/mm/dump_pagetables.c:458:\tptdump_walk_pgd(\u0026st.ptdump, mm, pgd);\narch/x86/mm/dump_pagetables.c-459-\n--\narch/x86/mm/dump_pagetables.c-473-\narch/x86/mm/dump_pagetables.c:474:void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)\narch/x86/mm/dump_pagetables.c-475-{\narch/x86/mm/dump_pagetables.c:476:\tptdump_walk_pgd_level_core(m, mm, mm-\u003epgd, false, true);\narch/x86/mm/dump_pagetables.c-477-}\narch/x86/mm/dump_pagetables.c-478-\narch/x86/mm/dump_pagetables.c:479:void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,\narch/x86/mm/dump_pagetables.c-480-\t\t\t\t   bool user)\n--\narch/x86/mm/dump_pagetables.c-486-#endif\narch/x86/mm/dump_pagetables.c:487:\tptdump_walk_pgd_level_core(m, mm, pgd, false, false);\narch/x86/mm/dump_pagetables.c-488-}\n--\narch/x86/mm/dump_pagetables.c=490=void ptdump_walk_user_pgd_level_checkwx(void)\n--\narch/x86/mm/dump_pagetables.c-500-\tpgd = kernel_to_user_pgdp(pgd);\narch/x86/mm/dump_pagetables.c:501:\tptdump_walk_pgd_level_core(NULL, \u0026init_mm, pgd, true, false);\narch/x86/mm/dump_pagetables.c-502-#endif\n--\narch/x86/mm/dump_pagetables.c-504-\narch/x86/mm/dump_pagetables.c:505:bool ptdump_walk_pgd_level_checkwx(void)\narch/x86/mm/dump_pagetables.c-506-{\n--\narch/x86/mm/dump_pagetables.c-509-\narch/x86/mm/dump_pagetables.c:510:\treturn ptdump_walk_pgd_level_core(NULL, \u0026init_mm, INIT_PGD, true, false);\narch/x86/mm/dump_pagetables.c-511-}\n--\narch/x86/platform/efi/efi_32.c=75=void __init efi_dump_pagetable(void)\n--\narch/x86/platform/efi/efi_32.c-77-#ifdef CONFIG_EFI_PGT_DUMP\narch/x86/platform/efi/efi_32.c:78:\tptdump_walk_pgd_level(NULL, \u0026init_mm);\narch/x86/platform/efi/efi_32.c-79-#endif\n--\narch/x86/platform/efi/efi_64.c=423=void __init efi_dump_pagetable(void)\n--\narch/x86/platform/efi/efi_64.c-425-#ifdef CONFIG_EFI_PGT_DUMP\narch/x86/platform/efi/efi_64.c:426:\tptdump_walk_pgd_level(NULL, \u0026efi_mm);\narch/x86/platform/efi/efi_64.c-427-#endif\n--\ninclude/linux/ptdump.h=13=struct ptdump_state {\n--\ninclude/linux/ptdump.h-27-\ninclude/linux/ptdump.h:28:bool ptdump_walk_pgd_level_core(struct seq_file *m,\ninclude/linux/ptdump.h-29-\t\t\t\tstruct mm_struct *mm, pgd_t *pgd,\ninclude/linux/ptdump.h-30-\t\t\t\tbool checkwx, bool dmesg);\ninclude/linux/ptdump.h:31:void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd);\ninclude/linux/ptdump.h-32-bool ptdump_check_wx(void);\n--\nmm/ptdump.c=166=static const struct mm_walk_ops ptdump_ops = {\n--\nmm/ptdump.c-174-\nmm/ptdump.c:175:void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)\nmm/ptdump.c-176-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 11104
							output: 23
							thoughts: 58
						

Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Investigating the ptdump Walk Trigger**

Right, so the `ptdump` walk, as I recall, is initiated through those debugfs files. Let's get to the heart of how that's configured. My instinct is to dive into the architecture-specific implementations. The logical place to start digging is in `arch/x86/mm/debug_pagetables.c` and `arch/arm64/mm/ptdump.c`. That should show me precisely how the debugfs entries are created and linked to the `ptdump` functionality. I need to understand the mechanism; I'm betting one of these files will be the key. This will help me trace the call path. Once I see how debugfs is wired in, I should be able to deduce the interactions of the files involved.

{
  "Expression": "debugfs_create_file.*ptdump"
}

{
  "Output": "arch/arm/mm/ptdump_debugfs.c=16=void __init ptdump_debugfs_register(struct ptdump_info *info, const char *name)\narch/arm/mm/ptdump_debugfs.c-17-{\narch/arm/mm/ptdump_debugfs.c:18:\tdebugfs_create_file(name, 0400, NULL, info, \u0026ptdump_fops);\narch/arm/mm/ptdump_debugfs.c-19-}\n--\narch/arm64/mm/ptdump_debugfs.c=16=void __init ptdump_debugfs_register(struct ptdump_info *info, const char *name)\narch/arm64/mm/ptdump_debugfs.c-17-{\narch/arm64/mm/ptdump_debugfs.c:18:\tdebugfs_create_file(name, 0400, NULL, info, \u0026ptdump_fops);\narch/arm64/mm/ptdump_debugfs.c-19-}\n--\narch/powerpc/mm/ptdump/ptdump.c=406=static int __init ptdump_init(void)\n--\narch/powerpc/mm/ptdump/ptdump.c-420-\tif (IS_ENABLED(CONFIG_PTDUMP_DEBUGFS))\narch/powerpc/mm/ptdump/ptdump.c:421:\t\tdebugfs_create_file(\"kernel_page_tables\", 0400, NULL, NULL, \u0026ptdump_fops);\narch/powerpc/mm/ptdump/ptdump.c-422-\n--\narch/s390/mm/dump_pagetables.c=315=static int pt_dump_init(void)\n--\narch/s390/mm/dump_pagetables.c-356-#ifdef CONFIG_PTDUMP_DEBUGFS\narch/s390/mm/dump_pagetables.c:357:\tdebugfs_create_file(\"kernel_page_tables\", 0400, NULL, NULL, \u0026ptdump_fops);\narch/s390/mm/dump_pagetables.c-358-#endif /* CONFIG_PTDUMP_DEBUGFS */\n--\narch/x86/mm/debug_pagetables.c=49=static int __init pt_dump_debug_init(void)\n--\narch/x86/mm/debug_pagetables.c-52-\narch/x86/mm/debug_pagetables.c:53:\tdebugfs_create_file(\"kernel\", 0400, dir, NULL, \u0026ptdump_fops);\narch/x86/mm/debug_pagetables.c-54-\tdebugfs_create_file(\"current_kernel\", 0400, dir, NULL,\n--\narch/x86/mm/debug_pagetables.c-61-#if defined(CONFIG_EFI) \u0026\u0026 defined(CONFIG_X86_64)\narch/x86/mm/debug_pagetables.c:62:\tdebugfs_create_file(\"efi\", 0400, dir, NULL, \u0026ptdump_efi_fops);\narch/x86/mm/debug_pagetables.c-63-#endif\n"
}

gemini-3.1-pro-preview

null

null

							input: 12203
							output: 34
							thoughts: 52
						

Here's my thought process, as if I were working through this:

**Investigating a Kernel Configuration Dependency**

Okay, so I see that `CONFIG_PTDUMP_DEBUGFS` is required. That's a starting point, but I'm not going to jump to conclusions. I need to figure out *why* it's needed. Immediately, I'm thinking, "Is this just always on, or conditional?" I remember seeing `arch/x86/mm/debug_pagetables.c` floating around recently, and that *felt* conditional in its compilation. So, my next logical step is to check the `arch/x86/mm/Makefile`. That's where the conditional compilation logic would be. I need to see if this particular feature is dependent on other variables or if there's more to it than meets the eye. Let's see what's in that Makefile.

{
  "Expression": "debug_pagetables",
  "PathPrefix": "arch/x86/mm/Makefile"
}

{
  "Output": "arch/x86/mm/Makefile=37=obj-$(CONFIG_PTDUMP)\t\t+= dump_pagetables.o\narch/x86/mm/Makefile:38:obj-$(CONFIG_PTDUMP_DEBUGFS)\t+= debug_pagetables.o\narch/x86/mm/Makefile-39-\n"
}

gemini-3.1-pro-preview

null

null

							input: 12576
							output: 35
							thoughts: 138
						

Okay, here's my interpretation of these thoughts, formatted as you requested:

**Analyzing Kernel Memory Mapping Changes**

Right, so we're dealing with a patch that's going to trigger some page table dumps, and it's enabled by `CONFIG_PTDUMP_DEBUGFS`. That's good, helpful for debugging. And, aha, `CONFIG_DEBUG_WX` also does it, meaning the system will dump ptdumps at boot. That narrows down the circumstances in which this code executes.

The core of the change seems to be in `mm/vmalloc.c` and `arch/x86/mm/pat/set_memory.c`. I need to dig into those files to understand the specifics. Okay, focusing on `mm/vmalloc.c`, the patch touches `vmap_try_huge_pmd`, `vmap_try_huge_pud`, and `vmap_try_huge_p4d`. Those are all related to huge page mapping within `vmalloc`. That means this is all very relevant to kernel memory allocation, particularly when `CONFIG_HAVE_ARCH_HUGE_VMAP` is enabled. That should be pretty straightforward, if this is enabled, it should work as is. Time to pull up `mm/vmalloc.c` and see what's actually changed within those functions.

{
  "Expression": "vmap_try_huge_pmd",
  "PathPrefix": "mm/vmalloc.c"
}

{
  "Output": "mm/vmalloc.c=95=static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,\n--\nmm/vmalloc.c-142-\nmm/vmalloc.c:143:static int vmap_try_huge_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,\nmm/vmalloc.c-144-\t\t\tphys_addr_t phys_addr, pgprot_t prot,\n--\nmm/vmalloc.c=179=static int vmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,\n--\nmm/vmalloc.c-192-\nmm/vmalloc.c:193:\t\tif (vmap_try_huge_pmd(pmd, addr, next, phys_addr, prot,\nmm/vmalloc.c-194-\t\t\t\t\tmax_page_shift)) {\n--\nmm/vmalloc.c=206=static int vmap_try_huge_pud(pud_t *pud, unsigned long addr, unsigned long end,\n--\nmm/vmalloc.c-227-\nmm/vmalloc.c:228:\t/* See comment in vmap_try_huge_pmd(). */\nmm/vmalloc.c-229-\tscoped_cond_guard(mmap_read_lock_try, return 0, \u0026init_mm) {\n--\nmm/vmalloc.c=263=static int vmap_try_huge_p4d(p4d_t *p4d, unsigned long addr, unsigned long end,\n--\nmm/vmalloc.c-284-\nmm/vmalloc.c:285:\t/* See comment in vmap_try_huge_pmd(). */\nmm/vmalloc.c-286-\tscoped_cond_guard(mmap_read_lock_try, return 0, \u0026init_mm) {\n"
}

gemini-3.1-pro-preview

null

null

							input: 13528
							output: 36
							thoughts: 20
						

Okay, here's my summary, taking the perspective of someone deeply familiar with kernel internals and conditional compilation:

**Checking Conditional Compilation of `vmap_try_huge_pmd`**

Right, let's get down to brass tacks. I need to quickly ascertain the conditional compilation status of `vmap_try_huge_pmd`. There's no time to waste wading through everything. I want a definitive answer about whether or not this function is *always* present in the build, or if it's gated behind some configuration macro. Time to quickly find out if I need to even consider the possibility that it might be unavailable on a given target. I need to know which potential architectures, features, or configurations will impact its presence.

{
  "Expression": "HAVE_ARCH_HUGE_VMAP",
  "PathPrefix": "mm/vmalloc.c"
}

{
  "Output": "mm/vmalloc.c-53-\nmm/vmalloc.c:54:#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP\nmm/vmalloc.c-55-static unsigned int __ro_after_init ioremap_max_page_shift = BITS_PER_LONG - 1;\n--\nmm/vmalloc.c=62=early_param(\"nohugeiomap\", set_nohugeiomap);\nmm/vmalloc.c:63:#else /* CONFIG_HAVE_ARCH_HUGE_VMAP */\nmm/vmalloc.c-64-static const unsigned int ioremap_max_page_shift = PAGE_SHIFT;\nmm/vmalloc.c:65:#endif\t/* CONFIG_HAVE_ARCH_HUGE_VMAP */\nmm/vmalloc.c-66-\n"
}

gemini-3.1-pro-preview

null

null

							input: 13952
							output: 34
							thoughts: 74
						

**Examining the Conditional Compilation of `vmap_try_huge_pmd`**

Okay, hold on a second. I was under the impression that `vmap_try_huge_pmd` was only compiled in if we had `CONFIG_HAVE_ARCH_HUGE_VMAP` defined, but that doesn't seem to be the case. It looks like it's unconditionally included in the build. This is interesting.

So, even if the architecture *doesn't* support huge vmaps, the function still exists in the compiled code, albeit potentially doing nothing. I need to dig deeper into the implementation of `vmap_try_huge_pmd` itself to fully grasp what's going on here. Specifically, I need to see what conditions would trigger it to actually *do* something, and under what conditions it simply returns a value without taking any action. The relationship between `max_page_shift` and `PMD_SHIFT` is obviously key. I'll take a look at the code and see what that's all about.

{
  "File": "mm/vmalloc.c",
  "FirstLine": 143,
  "LineCount": 40
}

{
  "Contents": " 143:\tstatic int vmap_try_huge_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,\n 144:\t\t\t\tphys_addr_t phys_addr, pgprot_t prot,\n 145:\t\t\t\tunsigned int max_page_shift)\n 146:\t{\n 147:\t\tif (max_page_shift \u003c PMD_SHIFT)\n 148:\t\t\treturn 0;\n 149:\t\n 150:\t\tif (!arch_vmap_pmd_supported(prot))\n 151:\t\t\treturn 0;\n 152:\t\n 153:\t\tif ((end - addr) != PMD_SIZE)\n 154:\t\t\treturn 0;\n 155:\t\n 156:\t\tif (!IS_ALIGNED(addr, PMD_SIZE))\n 157:\t\t\treturn 0;\n 158:\t\n 159:\t\tif (!IS_ALIGNED(phys_addr, PMD_SIZE))\n 160:\t\t\treturn 0;\n 161:\t\n 162:\t\tif (!pmd_present(*pmd))\n 163:\t\t\treturn pmd_set_huge(pmd, phys_addr, prot);\n 164:\t\n 165:\t\t/*\n 166:\t\t * Acquire the mmap read lock to exclude ptdump, which walks\n 167:\t\t * kernel page tables it does not own under the mmap write lock.\n 168:\t\t *\n 169:\t\t * Concurrent read lock holders are safe: each exclusively owns\n 170:\t\t * the range it operates on and cannot reach this page table.\n 171:\t\t */\n 172:\t\tscoped_cond_guard(mmap_read_lock_try, return 0, \u0026init_mm) {\n 173:\t\t\tif (!pmd_free_pte_page(pmd, addr))\n 174:\t\t\t\treturn 0;\n 175:\t\t\treturn pmd_set_huge(pmd, phys_addr, prot);\n 176:\t\t}\n 177:\t}\n 178:\t\n 179:\tstatic int vmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,\n 180:\t\t\t\tphys_addr_t phys_addr, pgprot_t prot,\n 181:\t\t\t\tunsigned int max_page_shift, pgtbl_mod_mask *mask)\n 182:\t{\n"
}

gemini-3.1-pro-preview

null

null

							input: 14930
							output: 43
							thoughts: 160
						

**My Analysis of Huge Page Mapping**

Okay, let me break this down. From what I'm seeing, this `max_page_shift` value is ultimately derived from either `ioremap_max_page_shift` or `vmap_max_page_shift`. Now, if `CONFIG_HAVE_ARCH_HUGE_VMAP` isn't enabled, then `ioremap_max_page_shift` simply defaults to `PAGE_SHIFT`. This means that if that condition is met, `max_page_shift` will *always* be less than `PMD_SHIFT`, right? Consequently, the function is going to bail out and return 0. So, it's clear: to even *consider* the modified logic within `vmap_try_huge_pmd`, `CONFIG_HAVE_ARCH_HUGE_VMAP` *must* be defined. Now, I should probably check how `cpa_collapse_large_pages` is handled, especially within `arch/x86/mm/pat/set_memory.c`.

{
  "Expression": "cpa_collapse_large_pages",
  "PathPrefix": "arch/x86/mm/pat/set_memory.c"
}

{
  "Output": "arch/x86/mm/pat/set_memory.c=412=static int collapse_large_pages(unsigned long addr, struct list_head *pgtables);\narch/x86/mm/pat/set_memory.c-413-\narch/x86/mm/pat/set_memory.c:414:static void __cpa_collapse_large_pages(struct cpa_data *cpa)\narch/x86/mm/pat/set_memory.c-415-{\n--\narch/x86/mm/pat/set_memory.c-445-\narch/x86/mm/pat/set_memory.c:446:static void cpa_collapse_large_pages(struct cpa_data *cpa)\narch/x86/mm/pat/set_memory.c-447-{\n--\narch/x86/mm/pat/set_memory.c-454-\tscoped_guard(mmap_write_lock, \u0026init_mm)\narch/x86/mm/pat/set_memory.c:455:\t\t__cpa_collapse_large_pages(cpa);\narch/x86/mm/pat/set_memory.c-456-}\n--\narch/x86/mm/pat/set_memory.c=458=static void cpa_flush(struct cpa_data *cpa, int cache)\n--\narch/x86/mm/pat/set_memory.c-493-\tif (cpa-\u003eflags \u0026 CPA_COLLAPSE)\narch/x86/mm/pat/set_memory.c:494:\t\tcpa_collapse_large_pages(cpa);\narch/x86/mm/pat/set_memory.c-495-}\n"
}

gemini-3.1-pro-preview

null

null

							input: 15817
							output: 33
							thoughts: 95
						

Okay, here's my interpretation of this technical snippet, from my perspective as a seasoned systems engineer:

**Deconstructing Memory Attribute Changes**

Right, so `cpa_collapse_large_pages` is getting triggered from `cpa_flush`. That's interesting, and it immediately puts me in mind of memory management and potential performance implications. Looking closer, it appears to be part of `change_page_attr_set_clr`, which is a pretty clear indicator that we're talking about modifying memory attributes. Things like read-only, no-execute, etc. are handled here.

The fact that this is *always* compiled on x86 is a crucial detail. It suggests this particular logic is tightly coupled to the architecture. I'd be willing to bet this optimization is specific to x86's memory model and page table management. This hints at something potentially leveraging specific CPU features.

Now, I need to get a better handle on the `walk_page_range_debug` function mentioned. A quick look at `mm/pagewalk.c` will probably clarify how this page range manipulation operates. It'll give me a clearer picture of how it's integrated with the more general memory management structures. I suspect this function is involved in iterating through page table entries and applying the attribute changes efficiently. Let's see how deep this rabbit hole goes.

{
  "Expression": "walk_page_range_debug",
  "PathPrefix": "mm/pagewalk.c"
}

{
  "Output": "mm/pagewalk.c=648=int walk_kernel_page_table_range_lockless(unsigned long start, unsigned long end,\n--\nmm/pagewalk.c-667-/**\nmm/pagewalk.c:668: * walk_page_range_debug - walk a range of pagetables not backed by a vma\nmm/pagewalk.c-669- * @mm:\t\tmm_struct representing the target process of page table walk\n--\nmm/pagewalk.c-683- */\nmm/pagewalk.c:684:int walk_page_range_debug(struct mm_struct *mm, unsigned long start,\nmm/pagewalk.c-685-\t\t\t  unsigned long end, const struct mm_walk_ops *ops,\n"
}

gemini-3.1-pro-preview

null

null

							input: 16432
							output: 24
							thoughts: 202
						

**Analyzing the Changes to Page Table Debugging**

Okay, so I'm looking at this patch and it seems like the key function here is `walk_page_range_debug`, which is called by `ptdump_walk_pgd` in `mm/ptdump.c`. The main addition is an `mmap_assert_write_locked(&init_mm)` call inside `walk_page_range_debug`. That's interesting, implies we're trying to tighten up some locking around the initial memory map. Makes sense, given that we're digging around in page tables and need to be careful about concurrent access.

Let me see, the functions really in play here are `vmap_try_huge_pmd`, `vmap_try_huge_pud`, `vmap_try_huge_p4d`, `ptdump_walk_pgd`, `cpa_collapse_large_pages` and of course `walk_page_range_debug`. I need to understand how these interact with each other in this new context.

The enabling configurations seem to be `PTDUMP_DEBUGFS`, `DEBUG_WX`, and `HAVE_ARCH_HUGE_VMAP`. I'm going to quickly check `HAVE_ARCH_HUGE_VMAP` to make sure it's a configuration option and not just a macro. It's important to understand how these flags affect the overall behavior and what architectures this change impacts. This is pretty standard when assessing these kind of changes. Gotta make sure we're not inadvertently breaking something on a particular architecture or configuration.

{
  "Expression": "config HAVE_ARCH_HUGE_VMAP"
}

{
  "Output": "arch/Kconfig=1089=config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD\n--\narch/Kconfig-1091-\narch/Kconfig:1092:config HAVE_ARCH_HUGE_VMAP\narch/Kconfig-1093-\tbool\n"
}

gemini-3.1-pro-preview

null

null

							input: 17085
							output: 20
							thoughts: 54
						

**Analyzing the Configuration Option**

Okay, so this is definitely a configuration option, that's clear. But I need to understand its context fully. Are there *other* related configuration options that I should be aware of, which could impact this one? The dependency graph is the key here. Let's see... Ah, `CONFIG_PTDUMP_CORE` is *selected* by both `PTDUMP_DEBUGFS` and `DEBUG_WX`. That's important. It tells me immediately that the state of *this* particular feature is controlled by a couple of other things. Now I should probably double check the dependency `PTDUMP_DEBUGFS` to see if there are other potential impacts. I need to fully understand its relationship and the implications before I move forward.

{
  "Expression": "config PTDUMP_DEBUGFS"
}

{
  "Output": "mm/Kconfig.debug=219=config PTDUMP\n--\nmm/Kconfig.debug-221-\nmm/Kconfig.debug:222:config PTDUMP_DEBUGFS\nmm/Kconfig.debug-223-\tbool \"Export kernel pagetable layout to userspace via debugfs\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 17408
							output: 18
							thoughts: 9
						

Okay, here's my summarized thought process, assuming I'm an expert and this is a deep dive into debugging:

**Debugging Initiative: The `DEBUG_WX` Variable**

Alright, time to troubleshoot. The first thing I'm going to do is immediately check the status of `DEBUG_WX`. That variable is usually the linchpin in this type of problem, and I am betting I am going to find something there. Is it on, off, set incorrectly? Its state will steer the next move. This will likely provide initial context for the cause.

{
  "Expression": "config DEBUG_WX"
}

{
  "Output": "mm/Kconfig.debug=183=config ARCH_HAS_DEBUG_WX\n--\nmm/Kconfig.debug-185-\nmm/Kconfig.debug:186:config DEBUG_WX\nmm/Kconfig.debug-187-\tbool \"Warn on W+X mappings at boot\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 17640
							output: 34
							thoughts: 78
						

Okay, let's see what we've got here.

**Kernel Configuration Investigation**

Alright, so `PTDUMP_DEBUGFS` and `DEBUG_WX` look promising as starting points. Now, I need to understand this `CONFIG_X86_PAT` directive. Hmmm, the associated file is `arch/x86/mm/pat/set_memory.c`. The question is, is this file conditionally compiled based on `CONFIG_X86_PAT`? Let's quickly verify by opening and checking the `arch/x86/mm/pat/Makefile`. That should reveal the build dependencies. That'll give me a definitive answer.

{
  "Expression": "set_memory",
  "PathPrefix": "arch/x86/mm/pat/Makefile"
}

{
  "Output": "arch/x86/mm/pat/Makefile-2-\narch/x86/mm/pat/Makefile:3:obj-y\t\t\t\t:= set_memory.o memtype.o\narch/x86/mm/pat/Makefile-4-\n"
}

gemini-3.1-pro-preview

null

null

							input: 17968
							output: 34
							thoughts: 852
						

**Reviewing Recent Memory Management Changes**

Okay, let's take a look at these recent changes. It seems like the core focus is on memory mapping and page table manipulation, and it's all compiled, of course.

First, in `mm/vmalloc.c`, there's a functional change related to vmalloc huge pages. Specifically, they've added a lock using `scoped_cond_guard` within `pmd_free_pte_page`. This suggests they're trying to improve synchronization when mapping these huge pages, which is good to see.

Then, in `arch/x86/mm/pat/set_memory.c`, the `cpa_collapse_large_pages` function is getting a lock as well, using `scoped_guard`. It seems this is for serializing concurrent CPA walkers and avoiding use-after-free conditions related to the `ptdump` functionality. That also makes sense.

Next, the `mm/ptdump.c` file has modifications related to the `init_mm` locking within `ptdump_walk_pgd`. They're acquiring the `init_mm` lock now, which is definitely designed to improve stability of kernel page tables by acquiring a lock on `init_mm`, so a good change.

Finally, in `arch/arm64/mm/mmu.c`, they've removed the `arm64_ptdump_lock_key` static branch and the `mmap_read_lock(&init_mm)` from `pmd_free_pte_page` and `pud_free_pmd_page`. This seems to be a cleanup and simplification, perhaps after previous locking changes or improvements.

Overall, this looks like a good set of changes, especially with respect to locking and synchronization. These are all changes that are definitely worth fuzzing. I think the key areas to focus on during fuzzing will be the following symbols: `vmap_try_huge_pmd`, `vmap_try_huge_pud`, `vmap_try_huge_p4d`, `cpa_collapse_large_pages`, `ptdump_walk_pgd`, and `walk_page_range_debug`.

As for configs, `PTDUMP_DEBUGFS`, `DEBUG_WX`, and `HAVE_ARCH_HUGE_VMAP` seem relevant. I should check if `HAVE_ARCH_HUGE_VMAP` is user-selectable, because that's always useful for fuzzer selection and configuration.

{
  "Expression": "config HAVE_ARCH_HUGE_VMAP",
  "PathPrefix": "arch/Kconfig"
}

{
  "Output": "arch/Kconfig=1089=config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD\n--\narch/Kconfig-1091-\narch/Kconfig:1092:config HAVE_ARCH_HUGE_VMAP\narch/Kconfig-1093-\tbool\n"
}

gemini-3.1-pro-preview

null

null

							input: 19482
							output: 38
							thoughts: 44
						

Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Architectural Selection, Not User Choice**

Right, so we're talking about a feature, or perhaps a configuration option, and it's not something the end-user gets to twiddle with directly. The crucial point here is that the *architecture itself* determines whether it's enabled or not. Think of it like this: the hardware platform itself, its fundamental design, is what's making the call. It's not a compile-time flag the user can simply flip.

The example highlights that clearly, like x86 and arm64 architectures are the ones making that selection, which helps contextualize what is going on.

To really nail this down, I'm going to jump into the code and start with the standard location for x86-specific configurations. Let me see what `arch/x86/Kconfig` reveals. That's usually the best place to start.

{
  "Expression": "select HAVE_ARCH_HUGE_VMAP",
  "PathPrefix": "arch/x86/Kconfig"
}

{
  "Output": "arch/x86/Kconfig=58=config X86\n--\narch/x86/Kconfig-191-\tselect HAVE_ARCH_AUDITSYSCALL\narch/x86/Kconfig:192:\tselect HAVE_ARCH_HUGE_VMAP\t\tif X86_64 || X86_PAE\narch/x86/Kconfig-193-\tselect HAVE_ARCH_HUGE_VMALLOC\t\tif X86_64\n"
}

gemini-3.1-pro-preview

null

null

							input: 19905
							output: 199
							thoughts: 228
						

**Kernel Configuration Tweaks for Improved Debugging**

Okay, so the x86_64 architecture has huge vmaps enabled by default, so I don't technically *need* to explicitly enable it. However, it wouldn't hurt to list it in the configuration. But hang on, `HAVE_ARCH_HUGE_VMAP` is a straight boolean, no prompt, so I can't directly enable it in the `.config` file. I'm better off omitting it entirely, or just listing it, since syzbot will just ignore it if it can't be set. But yes, I should definitely list `PTDUMP_DEBUGFS` and `DEBUG_WX`. Those are critical.

Let me double-check `cpa_collapse_large_pages`. It's defined statically. But the information might be useful, so let's list it anyway. Wait a second... `cpa_collapse_large_pages` is called from `cpa_flush`. Okay, that seals it. I should *definitely* list `cpa_collapse_large_pages`. As well as `ptdump_walk_pgd`, `vmap_try_huge_pmd`, and `vmap_try_huge_pud` and `vmap_try_huge_p4d`. Those all seem relevant to the debugging process.

Right, I think that's the core of the configuration changes done. Now, let's call `set-results`.

{
  "EnableConfigs": [
    "PTDUMP_DEBUGFS",
    "DEBUG_WX"
  ],
  "FocusSymbols": [
    "vmap_try_huge_pmd",
    "vmap_try_huge_pud",
    "vmap_try_huge_p4d",
    "cpa_collapse_large_pages",
    "ptdump_walk_pgd",
    "walk_page_range_debug"
  ],
  "Reasoning": "The patch modifies synchronization between page table dumping (ptdump), vmalloc huge page mappings, and x86 CPA (change page attribute) large page collapsing. It introduces new locking using mmap_read_lock/mmap_write_lock on init_mm. These are functional changes in core memory management and architecture-specific code that should be fuzzed to ensure no deadlocks or use-after-free issues occur.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "PTDUMP_DEBUGFS",
    "DEBUG_WX"
  ],
  "FocusSymbols": [
    "vmap_try_huge_pmd",
    "vmap_try_huge_pud",
    "vmap_try_huge_p4d",
    "cpa_collapse_large_pages",
    "ptdump_walk_pgd",
    "walk_page_range_debug"
  ],
  "Reasoning": "The patch modifies synchronization between page table dumping (ptdump), vmalloc huge page mappings, and x86 CPA (change page attribute) large page collapsing. It introduces new locking using mmap_read_lock/mmap_write_lock on init_mm. These are functional changes in core memory management and architecture-specific code that should be fuzzed to ensure no deadlocks or use-after-free issues occur.",
  "WorthFuzzing": true
}