AI Trajectory

null

{
  "EnableConfigs": [
    "ADVISE_SYSCALLS"
  ],
  "FocusSymbols": [
    "do_mincore",
    "madvise_pageout",
    "madvise_cold_or_pageout_pte_range"
  ],
  "Reasoning": "The patch fixes a bug where idmapped mounts were not properly handled in `madvise` and `mincore` by replacing `\u0026nop_mnt_idmap` with the actual mount idmap of the file. This is a functional change in core memory management logic.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit cdf291319d7c9584ac878ac287031e6a39399e59\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Thu Jun 25 15:57:09 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/linux/fs.h b/include/linux/fs.h\nindex d10897b3a1e350..50ce731a2b78f1 100644\n--- a/include/linux/fs.h\n+++ b/include/linux/fs.h\n@@ -2444,6 +2444,11 @@ static inline struct mnt_idmap *file_mnt_idmap(const struct file *file)\n \treturn mnt_idmap(file-\u003ef_path.mnt);\n }\n \n+static inline bool file_owner_or_capable(const struct file *file)\n+{\n+\treturn inode_owner_or_capable(file_mnt_idmap(file), file_inode(file));\n+}\n+\n /**\n  * is_idmapped_mnt - check whether a mount is mapped\n  * @mnt: the mount to check\ndiff --git a/mm/filemap.c b/mm/filemap.c\nindex 5af62e6abca58b..58eb9d24064348 100644\n--- a/mm/filemap.c\n+++ b/mm/filemap.c\n@@ -4704,7 +4704,7 @@ static inline bool can_do_cachestat(struct file *f)\n {\n \tif (f-\u003ef_mode \u0026 FMODE_WRITE)\n \t\treturn true;\n-\tif (inode_owner_or_capable(file_mnt_idmap(f), file_inode(f)))\n+\tif (file_owner_or_capable(f))\n \t\treturn true;\n \treturn file_permission(f, MAY_WRITE) == 0;\n }\ndiff --git a/mm/madvise.c b/mm/madvise.c\nindex cd9bb077072ccb..77552b03d318d9 100644\n--- a/mm/madvise.c\n+++ b/mm/madvise.c\n@@ -336,8 +336,7 @@ static inline bool can_do_file_pageout(struct vm_area_struct *vma)\n \t * otherwise we'd be including shared non-exclusive mappings, which\n \t * opens a side channel.\n \t */\n-\treturn inode_owner_or_capable(\u0026nop_mnt_idmap,\n-\t\t\t\t      file_inode(vma-\u003evm_file)) ||\n+\treturn file_owner_or_capable(vma-\u003evm_file) ||\n \t       file_permission(vma-\u003evm_file, MAY_WRITE) == 0;\n }\n \ndiff --git a/mm/mincore.c b/mm/mincore.c\nindex 296f2e3922b5f4..c8757c5085bf90 100644\n--- a/mm/mincore.c\n+++ b/mm/mincore.c\n@@ -227,8 +227,7 @@ static inline bool can_do_mincore(struct vm_area_struct *vma)\n \t * for writing; otherwise we'd be including shared non-exclusive\n \t * mappings, which opens a side channel.\n \t */\n-\treturn inode_owner_or_capable(\u0026nop_mnt_idmap,\n-\t\t\t\t      file_inode(vma-\u003evm_file)) ||\n+\treturn file_owner_or_capable(vma-\u003evm_file) ||\n \t       file_permission(vma-\u003evm_file, MAY_WRITE) == 0;\n }\n \n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": [
    "ADVISE_SYSCALLS"
  ],
  "FocusSymbols": [
    "do_mincore",
    "madvise_pageout",
    "madvise_cold_or_pageout_pte_range"
  ],
  "Reasoning": "The patch fixes a bug where idmapped mounts were not properly handled in `madvise` and `mincore` by replacing `\u0026nop_mnt_idmap` with the actual mount idmap of the file. This is a functional change in core memory management logic.",
  "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 cdf291319d7c9584ac878ac287031e6a39399e59
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Jun 25 15:57:09 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/linux/fs.h b/include/linux/fs.h
index d10897b3a1e350..50ce731a2b78f1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2444,6 +2444,11 @@ static inline struct mnt_idmap *file_mnt_idmap(const struct file *file)
 	return mnt_idmap(file->f_path.mnt);
 }
 
+static inline bool file_owner_or_capable(const struct file *file)
+{
+	return inode_owner_or_capable(file_mnt_idmap(file), file_inode(file));
+}
+
 /**
  * is_idmapped_mnt - check whether a mount is mapped
  * @mnt: the mount to check
diff --git a/mm/filemap.c b/mm/filemap.c
index 5af62e6abca58b..58eb9d24064348 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -4704,7 +4704,7 @@ static inline bool can_do_cachestat(struct file *f)
 {
 	if (f->f_mode & FMODE_WRITE)
 		return true;
-	if (inode_owner_or_capable(file_mnt_idmap(f), file_inode(f)))
+	if (file_owner_or_capable(f))
 		return true;
 	return file_permission(f, MAY_WRITE) == 0;
 }
diff --git a/mm/madvise.c b/mm/madvise.c
index cd9bb077072ccb..77552b03d318d9 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -336,8 +336,7 @@ static inline bool can_do_file_pageout(struct vm_area_struct *vma)
 	 * otherwise we'd be including shared non-exclusive mappings, which
 	 * opens a side channel.
 	 */
-	return inode_owner_or_capable(&nop_mnt_idmap,
-				      file_inode(vma->vm_file)) ||
+	return file_owner_or_capable(vma->vm_file) ||
 	       file_permission(vma->vm_file, MAY_WRITE) == 0;
 }
 
diff --git a/mm/mincore.c b/mm/mincore.c
index 296f2e3922b5f4..c8757c5085bf90 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -227,8 +227,7 @@ static inline bool can_do_mincore(struct vm_area_struct *vma)
 	 * for writing; otherwise we'd be including shared non-exclusive
 	 * mappings, which opens a side channel.
 	 */
-	return inode_owner_or_capable(&nop_mnt_idmap,
-				      file_inode(vma->vm_file)) ||
+	return file_owner_or_capable(vma->vm_file) ||
 	       file_permission(vma->vm_file, MAY_WRITE) == 0;
 }
 

gemini-3.1-pro-preview

null

null

							input: 2502
							output: 42
							thoughts: 414
						

**Analyzing the File Permission Changes**

Okay, so this patch is introducing a new inline function, `file_owner_or_capable`, and I see it's intended to simplify some checks related to file ownership and capability. Specifically, it's replacing direct calls to `inode_owner_or_capable` with this new function in a few key areas: `mm/filemap.c`, `mm/madvise.c`, and `mm/mincore.c`.

Hold on... I'm noticing something crucial here, a functional change. In `mm/madvise.c` and `mm/mincore.c`, the original code was passing `&nop_mnt_idmap` to `inode_owner_or_capable`, but now the patch directly uses `file_owner_or_capable(vma->vm_file)`. This means it will call `inode_owner_or_capable(file_mnt_idmap(file), file_inode(file))`. So, the patch is changing the mount ID mapping used in the ownership check from a no-op to the actual file's mount ID. This has to be a fix! This addresses a known issue where ID-mapped mounts weren't being correctly handled within the `madvise` and `mincore` functions.

Now, I want to drill down further. Let's look closely at where these changes are impacting us. The logic now touches `can_do_file_pageout` within `mm/madvise.c` and `can_do_mincore` within `mm/mincore.c`. `can_do_file_pageout` is, as I recall, a function that's called from `madvise_pageout`. `can_do_mincore` is used by a function similar to `mincore_page_range` or similar in `mm/mincore.c`.

Time to see where these are used. I'll fire up `grepper` and see where these functions are actually called, making sure I understand the full scope of these changes, and what downstream impact this fix might have.

{
  "Expression": "can_do_file_pageout"
}

{
  "Output": "mm/madvise.c=281=static long madvise_willneed(struct madvise_behavior *madv_behavior)\n--\nmm/madvise.c-328-\nmm/madvise.c:329:static inline bool can_do_file_pageout(struct vm_area_struct *vma)\nmm/madvise.c-330-{\n--\nmm/madvise.c=353=static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,\n--\nmm/madvise.c-373-\tpageout_anon_only_filter = pageout \u0026\u0026 !vma_is_anonymous(vma) \u0026\u0026\nmm/madvise.c:374:\t\t\t\t\t!can_do_file_pageout(vma);\nmm/madvise.c-375-\n--\nmm/madvise.c=626=static long madvise_pageout(struct madvise_behavior *madv_behavior)\n--\nmm/madvise.c-639-\t */\nmm/madvise.c:640:\tif (!vma_is_anonymous(vma) \u0026\u0026 (!can_do_file_pageout(vma) \u0026\u0026\nmm/madvise.c-641-\t\t\t\t(vma-\u003evm_flags \u0026 VM_MAYSHARE)))\n"
}

{
  "Expression": "can_do_mincore"
}

{
  "Output": "mm/mincore.c=163=static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,\n--\nmm/mincore.c-217-\nmm/mincore.c:218:static inline bool can_do_mincore(struct vm_area_struct *vma)\nmm/mincore.c-219-{\n--\nmm/mincore.c=246=static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)\n--\nmm/mincore.c-255-\tend = min(vma-\u003evm_end, addr + (pages \u003c\u003c PAGE_SHIFT));\nmm/mincore.c:256:\tif (!can_do_mincore(vma)) {\nmm/mincore.c-257-\t\tunsigned long pages = DIV_ROUND_UP(end - addr, PAGE_SIZE);\n"
}

gemini-3.1-pro-preview

null

null

							input: 3991
							output: 20
							thoughts: 201
						

**Analyzing the idmapped mount change**

Okay, so this change tackles how idmapped mounts are handled within `madvise` and `mincore`. Interesting. It looks like they're replacing `&nop_mnt_idmap` with `file_mnt_idmap(vma->vm_file)`. This is definitely a functional shift, meaning there's a real possibility of finding some edge cases. Definitely worth throwing some fuzzing at it.

My initial thought was to focus on `madvise_pageout`, `madvise_cold_or_pageout_pte_range`, and `do_mincore`. Wait, re-reading the patch...it looks like the core change is actually within `can_do_file_pageout` and `can_do_mincore`. Ah, those are the functions that get called within the entry points, namely `madvise_pageout` and `do_mincore`.

Let me see if this is tied to any specific configurations. Idmapped mounts rely on `CONFIG_USER_NS` and `CONFIG_MULTIUSER`, I think? Though, idmapped mounts are generally available now, right? Okay, let's see if there is any other specific config that might be particularly relevant to this change.

{
  "Expression": "file_mnt_idmap"
}

{
  "Output": "drivers/block/zloop.c=700=static int zloop_record_safe_wps(struct zloop_device *zlo)\n--\ndrivers/block/zloop.c-710-\t\t\tcontinue;\ndrivers/block/zloop.c:711:\t\tret = vfs_setxattr(file_mnt_idmap(file), file_dentry(file),\ndrivers/block/zloop.c-712-\t\t\t\t\"user.zloop.wp\", \u0026zone-\u003ewp, sizeof(zone-\u003ewp), 0);\n--\ndrivers/block/zloop.c=1365=static void zloop_forget_cache(struct zloop_device *zlo)\n--\ndrivers/block/zloop.c-1379-\ndrivers/block/zloop.c:1380:\t\tret = vfs_getxattr(file_mnt_idmap(file), file_dentry(file),\ndrivers/block/zloop.c-1381-\t\t\t\t\"user.zloop.wp\", \u0026old_wp, sizeof(old_wp));\n--\nfs/btrfs/ioctl.c=1201=static noinline int btrfs_ioctl_snap_create(struct file *file,\n--\nfs/btrfs/ioctl.c-1216-\nfs/btrfs/ioctl.c:1217:\treturn __btrfs_ioctl_snap_create(file, file_mnt_idmap(file),\nfs/btrfs/ioctl.c-1218-\t\t\t\t\t vol_args-\u003ename, vol_args-\u003efd, subvol,\n--\nfs/btrfs/ioctl.c=1222=static noinline int btrfs_ioctl_snap_create_v2(struct file *file,\n--\nfs/btrfs/ioctl.c-1260-\nfs/btrfs/ioctl.c:1261:\treturn __btrfs_ioctl_snap_create(file, file_mnt_idmap(file),\nfs/btrfs/ioctl.c-1262-\t\t\t\t\t vol_args-\u003ename, vol_args-\u003efd, subvol,\n--\nfs/btrfs/ioctl.c=1288=static noinline int btrfs_ioctl_subvol_setflags(struct file *file,\n--\nfs/btrfs/ioctl.c-1298-\nfs/btrfs/ioctl.c:1299:\tif (!inode_owner_or_capable(file_mnt_idmap(file), inode))\nfs/btrfs/ioctl.c-1300-\t\treturn -EPERM;\n--\nfs/btrfs/ioctl.c=1921=static int btrfs_ioctl_ino_lookup_user(struct file *file, void __user *argp)\n--\nfs/btrfs/ioctl.c-1941-\nfs/btrfs/ioctl.c:1942:\tret = btrfs_search_path_in_tree_user(file_mnt_idmap(file), inode, args);\nfs/btrfs/ioctl.c-1943-\n--\nfs/btrfs/ioctl.c=2211=static noinline int btrfs_ioctl_snap_destroy(struct file *file,\n--\nfs/btrfs/ioctl.c-2223-\tstruct btrfs_ioctl_vol_args_v2 AUTO_KFREE(vol_args2);\nfs/btrfs/ioctl.c:2224:\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nfs/btrfs/ioctl.c-2225-\tchar *subvol_name, *subvol_name_ptr = NULL;\n--\nfs/btrfs/ioctl.c=3956=static long btrfs_ioctl_set_received_subvol_32(struct file *file,\n--\nfs/btrfs/ioctl.c-3979-\nfs/btrfs/ioctl.c:3980:\tret = _btrfs_ioctl_set_received_subvol(file, file_mnt_idmap(file), args64);\nfs/btrfs/ioctl.c-3981-\tif (ret)\n--\nfs/btrfs/ioctl.c=4001=static long btrfs_ioctl_set_received_subvol(struct file *file,\n--\nfs/btrfs/ioctl.c-4010-\nfs/btrfs/ioctl.c:4011:\tret = _btrfs_ioctl_set_received_subvol(file, file_mnt_idmap(file), sa);\nfs/btrfs/ioctl.c-4012-\tif (ret)\n--\nfs/ceph/file.c=793=int ceph_atomic_open(struct inode *dir, struct dentry *dentry,\n--\nfs/ceph/file.c-795-{\nfs/ceph/file.c:796:\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nfs/ceph/file.c-797-\tstruct ceph_fs_client *fsc = ceph_sb_to_fs_client(dir-\u003ei_sb);\n--\nfs/coredump.c=878=static bool coredump_file(struct core_name *cn, struct coredump_params *cprm,\n--\nfs/coredump.c-955-\t */\nfs/coredump.c:956:\tidmap = file_mnt_idmap(file);\nfs/coredump.c-957-\tif (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), current_fsuid())) {\n--\nfs/exec.c=1312=void would_dump(struct linux_binprm *bprm, struct file *file)\n--\nfs/exec.c-1314-\tstruct inode *inode = file_inode(file);\nfs/exec.c:1315:\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nfs/exec.c-1316-\tif (inode_permission(idmap, inode, MAY_READ) \u003c 0) {\n--\nfs/exec.c=1558=static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)\n--\nfs/exec.c-1577-\nfs/exec.c:1578:\tidmap = file_mnt_idmap(file);\nfs/exec.c-1579-\n--\nfs/exfat/file.c=445=static int exfat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)\n--\nfs/exfat/file.c-496-\t */\nfs/exfat/file.c:497:\terr = security_inode_setattr(file_mnt_idmap(file),\nfs/exfat/file.c-498-\t\t\t\t     file-\u003ef_path.dentry, \u0026ia);\n--\nfs/exfat/file.c-502-\t/* This MUST be done before doing anything irreversible... */\nfs/exfat/file.c:503:\terr = exfat_setattr(file_mnt_idmap(file), file-\u003ef_path.dentry, \u0026ia);\nfs/exfat/file.c-504-\tif (err)\n--\nfs/ext4/ioctl.c=1538=static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)\n--\nfs/ext4/ioctl.c-1541-\tstruct super_block *sb = inode-\u003ei_sb;\nfs/ext4/ioctl.c:1542:\tstruct mnt_idmap *idmap = file_mnt_idmap(filp);\nfs/ext4/ioctl.c-1543-\n--\nfs/f2fs/file.c=2279=static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)\n--\nfs/f2fs/file.c-2281-\tstruct inode *inode = file_inode(filp);\nfs/f2fs/file.c:2282:\tstruct mnt_idmap *idmap = file_mnt_idmap(filp);\nfs/f2fs/file.c-2283-\tstruct f2fs_inode_info *fi = F2FS_I(inode);\n--\nfs/f2fs/file.c=2391=static int f2fs_ioc_commit_atomic_write(struct file *filp)\n--\nfs/f2fs/file.c-2393-\tstruct inode *inode = file_inode(filp);\nfs/f2fs/file.c:2394:\tstruct mnt_idmap *idmap = file_mnt_idmap(filp);\nfs/f2fs/file.c-2395-\tint ret;\n--\nfs/f2fs/file.c=2426=static int f2fs_ioc_abort_atomic_write(struct file *filp)\n--\nfs/f2fs/file.c-2428-\tstruct inode *inode = file_inode(filp);\nfs/f2fs/file.c:2429:\tstruct mnt_idmap *idmap = file_mnt_idmap(filp);\nfs/f2fs/file.c-2430-\tint ret;\n--\nfs/fat/file.c=37=static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)\n--\nfs/fat/file.c-94-\t */\nfs/fat/file.c:95:\terr = security_inode_setattr(file_mnt_idmap(file),\nfs/fat/file.c-96-\t\t\t\t     file-\u003ef_path.dentry, \u0026ia);\n--\nfs/fat/file.c-100-\t/* This MUST be done before doing anything irreversible... */\nfs/fat/file.c:101:\terr = fat_setattr(file_mnt_idmap(file), file-\u003ef_path.dentry, \u0026ia);\nfs/fat/file.c-102-\tif (err)\n--\nfs/fcntl.c=39=static int setfl(int fd, struct file * filp, unsigned int arg)\n--\nfs/fcntl.c-52-\tif ((arg \u0026 O_NOATIME) \u0026\u0026 !(filp-\u003ef_flags \u0026 O_NOATIME))\nfs/fcntl.c:53:\t\tif (!inode_owner_or_capable(file_mnt_idmap(filp), inode))\nfs/fcntl.c-54-\t\t\treturn -EPERM;\n--\nfs/fcntl.c=369=static long fcntl_set_rw_hint(struct file *file, unsigned long arg)\n--\nfs/fcntl.c-374-\nfs/fcntl.c:375:\tif (!inode_owner_or_capable(file_mnt_idmap(file), inode))\nfs/fcntl.c-376-\t\treturn -EPERM;\n--\nfs/file_attr.c=324=int ioctl_setflags(struct file *file, unsigned int __user *argp)\nfs/file_attr.c-325-{\nfs/file_attr.c:326:\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nfs/file_attr.c-327-\tstruct dentry *dentry = file-\u003ef_path.dentry;\n--\nfs/file_attr.c=356=int ioctl_fssetxattr(struct file *file, void __user *argp)\nfs/file_attr.c-357-{\nfs/file_attr.c:358:\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nfs/file_attr.c-359-\tstruct dentry *dentry = file-\u003ef_path.dentry;\n--\nfs/fuse/dir.c=930=static int fuse_atomic_open(struct inode *dir, struct dentry *entry,\n--\nfs/fuse/dir.c-934-\tint err;\nfs/fuse/dir.c:935:\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nfs/fuse/dir.c-936-\tstruct fuse_conn *fc = get_fuse_conn(dir);\n--\nfs/fuse/file.c=1503=static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/fuse/file.c-1505-\tstruct file *file = iocb-\u003eki_filp;\nfs/fuse/file.c:1506:\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nfs/fuse/file.c-1507-\tstruct address_space *mapping = file-\u003ef_mapping;\n--\nfs/fuse/file.c=2716=static void fuse_do_truncate(struct file *file)\n--\nfs/fuse/file.c-2726-\nfs/fuse/file.c:2727:\tfuse_do_setattr(file_mnt_idmap(file), file_dentry(file), \u0026attr, file);\nfs/fuse/file.c-2728-}\n--\nfs/inode.c=2376=static int file_remove_privs_flags(struct file *file, unsigned int flags)\n--\nfs/inode.c-2385-\nfs/inode.c:2386:\tkill = dentry_needs_remove_privs(file_mnt_idmap(file), dentry);\nfs/inode.c-2387-\tif (kill \u003c 0)\n--\nfs/inode.c-2393-\nfs/inode.c:2394:\t\terror = __remove_privs(file_mnt_idmap(file), dentry, kill);\nfs/inode.c-2395-\t}\n--\nfs/locks.c=2136=vfs_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv)\n--\nfs/locks.c-2138-\tstruct inode *inode = file_inode(filp);\nfs/locks.c:2139:\tvfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(filp), inode);\nfs/locks.c-2140-\tint error;\n--\nfs/open.c=164=int do_ftruncate(struct file *file, loff_t length, unsigned int flags)\n--\nfs/open.c-193-\tscoped_guard(super_write, inode-\u003ei_sb)\nfs/open.c:194:\t\treturn do_truncate(file_mnt_idmap(file), dentry, length,\nfs/open.c-195-\t\t\t\t   ATTR_MTIME | ATTR_CTIME, file);\n--\nfs/remap_range.c=416=static bool may_dedupe_file(struct file *file)\nfs/remap_range.c-417-{\nfs/remap_range.c:418:\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nfs/remap_range.c-419-\tstruct inode *inode = file_inode(file);\n--\nfs/smb/server/oplock.c=1744=void create_posix_rsp_buf(char *cc, struct ksmbd_file *fp)\n--\nfs/smb/server/oplock.c-1747-\tstruct inode *inode = file_inode(fp-\u003efilp);\nfs/smb/server/oplock.c:1748:\tstruct mnt_idmap *idmap = file_mnt_idmap(fp-\u003efilp);\nfs/smb/server/oplock.c-1749-\tvfsuid_t vfsuid = i_uid_into_vfsuid(idmap, inode);\n--\nfs/smb/server/smb2pdu.c=4273=static int process_query_dir_entries(struct smb2_query_dir_private *priv)\nfs/smb/server/smb2pdu.c-4274-{\nfs/smb/server/smb2pdu.c:4275:\tstruct mnt_idmap\t*idmap = file_mnt_idmap(priv-\u003edir_fp-\u003efilp);\nfs/smb/server/smb2pdu.c-4276-\tstruct kstat\t\tkstat;\n--\nfs/smb/server/smb2pdu.c=4509=int smb2_query_dir(struct ksmbd_work *work)\n--\nfs/smb/server/smb2pdu.c-4545-\tif (!(dir_fp-\u003edaccess \u0026 FILE_LIST_DIRECTORY_LE) ||\nfs/smb/server/smb2pdu.c:4546:\t    inode_permission(file_mnt_idmap(dir_fp-\u003efilp),\nfs/smb/server/smb2pdu.c-4547-\t\t\t     file_inode(dir_fp-\u003efilp),\n--\nfs/smb/server/smb2pdu.c=4818=static int smb2_get_ea(struct ksmbd_work *work, struct ksmbd_file *fp,\n--\nfs/smb/server/smb2pdu.c-4827-\tconst struct path *path;\nfs/smb/server/smb2pdu.c:4828:\tstruct mnt_idmap *idmap = file_mnt_idmap(fp-\u003efilp);\nfs/smb/server/smb2pdu.c-4829-\n--\nfs/smb/server/smb2pdu.c=5431=static int find_file_posix_info(struct smb2_query_info_rsp *rsp,\n--\nfs/smb/server/smb2pdu.c-5435-\tstruct inode *inode = file_inode(fp-\u003efilp);\nfs/smb/server/smb2pdu.c:5436:\tstruct mnt_idmap *idmap = file_mnt_idmap(fp-\u003efilp);\nfs/smb/server/smb2pdu.c-5437-\tvfsuid_t vfsuid = i_uid_into_vfsuid(idmap, inode);\n--\nfs/smb/server/smb2pdu.c=5883=static int smb2_get_info_sec(struct ksmbd_work *work,\n--\nfs/smb/server/smb2pdu.c-5925-\nfs/smb/server/smb2pdu.c:5926:\tidmap = file_mnt_idmap(fp-\u003efilp);\nfs/smb/server/smb2pdu.c-5927-\tinode = file_inode(fp-\u003efilp);\n--\nfs/smb/server/smb2pdu.c=6234=static int smb2_rename(struct ksmbd_work *work,\n--\nfs/smb/server/smb2pdu.c-6273-\nfs/smb/server/smb2pdu.c:6274:\t\trc = ksmbd_vfs_setxattr(file_mnt_idmap(fp-\u003efilp),\nfs/smb/server/smb2pdu.c-6275-\t\t\t\t\t\u0026fp-\u003efilp-\u003ef_path,\n--\nfs/smb/server/smb2pdu.c=6373=static int set_file_basic_info(struct ksmbd_file *fp,\n--\nfs/smb/server/smb2pdu.c-6388-\tinode = file_inode(filp);\nfs/smb/server/smb2pdu.c:6389:\tidmap = file_mnt_idmap(filp);\nfs/smb/server/smb2pdu.c-6390-\n--\nfs/smb/server/smb2pdu.c=8357=static inline int fsctl_set_sparse(struct ksmbd_work *work, u64 id,\n--\nfs/smb/server/smb2pdu.c-8378-\nfs/smb/server/smb2pdu.c:8379:\tidmap = file_mnt_idmap(fp-\u003efilp);\nfs/smb/server/smb2pdu.c-8380-\n--\nfs/smb/server/smb_common.c=445=int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work, int info_level,\n--\nfs/smb/server/smb_common.c-454-\tstruct ksmbd_conn *conn = work-\u003econn;\nfs/smb/server/smb_common.c:455:\tstruct mnt_idmap *idmap = file_mnt_idmap(dir-\u003efilp);\nfs/smb/server/smb_common.c-456-\n--\nfs/smb/server/vfs.c=248=static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,\n--\nfs/smb/server/vfs.c-258-\tsaved_cred = override_creds(fp-\u003efilp-\u003ef_cred);\nfs/smb/server/vfs.c:259:\tv_len = ksmbd_vfs_getcasexattr(file_mnt_idmap(fp-\u003efilp),\nfs/smb/server/vfs.c-260-\t\t\t\t       fp-\u003efilp-\u003ef_path.dentry,\n--\nfs/smb/server/vfs.c=385=static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,\n--\nfs/smb/server/vfs.c-389-\tchar *stream_buf = NULL, *wbuf;\nfs/smb/server/vfs.c:390:\tstruct mnt_idmap *idmap = file_mnt_idmap(fp-\u003efilp);\nfs/smb/server/vfs.c-391-\tsize_t size;\n--\nfs/smb/server/vfs.c=1015=int ksmbd_vfs_unlink(struct file *filp)\n--\nfs/smb/server/vfs.c-1019-\tstruct dentry *dir, *dentry = filp-\u003ef_path.dentry;\nfs/smb/server/vfs.c:1020:\tstruct mnt_idmap *idmap = file_mnt_idmap(filp);\nfs/smb/server/vfs.c-1021-\n--\nfs/smb/server/vfs.c=1957=int ksmbd_vfs_set_compression(struct ksmbd_work *work, struct ksmbd_file *fp, u16 fmt)\n--\nfs/smb/server/vfs.c-1961-\tstruct dentry *dentry = fp-\u003efilp-\u003ef_path.dentry;\nfs/smb/server/vfs.c:1962:\tstruct mnt_idmap *idmap = file_mnt_idmap(fp-\u003efilp);\nfs/smb/server/vfs.c-1963-\tu32 flags;\n--\nfs/smb/server/vfs_cache.c=369=static void __ksmbd_inode_close(struct ksmbd_file *fp)\n--\nfs/smb/server/vfs_cache.c-390-\t\t\tsaved_cred = override_creds(filp-\u003ef_cred);\nfs/smb/server/vfs_cache.c:391:\t\t\terr = ksmbd_vfs_remove_xattr(file_mnt_idmap(filp),\nfs/smb/server/vfs_cache.c-392-\t\t\t\t\t\t     \u0026filp-\u003ef_path,\n--\nfs/xattr.c=666=int file_setxattr(struct file *f, struct kernel_xattr_ctx *ctx)\n--\nfs/xattr.c-671-\t\taudit_file(f);\nfs/xattr.c:672:\t\terror = do_setxattr(file_mnt_idmap(f), f-\u003ef_path.dentry, ctx);\nfs/xattr.c-673-\t\tmnt_drop_write_file(f);\n--\nfs/xattr.c=822=ssize_t file_getxattr(struct file *f, struct kernel_xattr_ctx *ctx)\n--\nfs/xattr.c-824-\taudit_file(f);\nfs/xattr.c:825:\treturn do_getxattr(file_mnt_idmap(f), f-\u003ef_path.dentry, ctx);\nfs/xattr.c-826-}\n--\nfs/xattr.c=1039=static int file_removexattr(struct file *f, struct xattr_name *kname)\n--\nfs/xattr.c-1044-\t\taudit_file(f);\nfs/xattr.c:1045:\t\terror = removexattr(file_mnt_idmap(f),\nfs/xattr.c-1046-\t\t\t\t    f-\u003ef_path.dentry, kname-\u003ename);\n--\nfs/xfs/xfs_file.c=1243=xfs_falloc_setsize(\n--\nfs/xfs/xfs_file.c-1253-\t\treturn 0;\nfs/xfs/xfs_file.c:1254:\treturn xfs_vn_setattr_size(file_mnt_idmap(file), file_dentry(file),\nfs/xfs/xfs_file.c-1255-\t\t\t\u0026iattr);\n--\nfs/xfs/xfs_ioctl.c=81=xfs_ioc_fsbulkstat(\n--\nfs/xfs/xfs_ioctl.c-89-\t\t.mp\t\t= mp,\nfs/xfs/xfs_ioctl.c:90:\t\t.idmap\t\t= file_mnt_idmap(file),\nfs/xfs/xfs_ioctl.c-91-\t\t.ocount\t\t= 0,\n--\nfs/xfs/xfs_ioctl.c=264=xfs_ioc_bulkstat(\n--\nfs/xfs/xfs_ioctl.c-272-\t\t.mp\t\t\t= mp,\nfs/xfs/xfs_ioctl.c:273:\t\t.idmap\t\t\t= file_mnt_idmap(file),\nfs/xfs/xfs_ioctl.c-274-\t};\n--\nfs/xfs/xfs_ioctl32.c=198=xfs_compat_ioc_fsbulkstat(\n--\nfs/xfs/xfs_ioctl32.c-207-\t\t.mp\t\t= mp,\nfs/xfs/xfs_ioctl32.c:208:\t\t.idmap\t\t= file_mnt_idmap(file),\nfs/xfs/xfs_ioctl32.c-209-\t\t.ocount\t\t= 0,\n--\ninclude/linux/fs.h=2440=static_assert(sizeof(struct filename) % 64 == 0);\ninclude/linux/fs.h-2441-\ninclude/linux/fs.h:2442:static inline struct mnt_idmap *file_mnt_idmap(const struct file *file)\ninclude/linux/fs.h-2443-{\n--\ninclude/linux/fs.h=2447=static inline bool file_owner_or_capable(const struct file *file)\ninclude/linux/fs.h-2448-{\ninclude/linux/fs.h:2449:\treturn inode_owner_or_capable(file_mnt_idmap(file), file_inode(file));\ninclude/linux/fs.h-2450-}\n--\ninclude/linux/fs.h=2694=static inline int file_permission(struct file *file, int mask)\ninclude/linux/fs.h-2695-{\ninclude/linux/fs.h:2696:\treturn inode_permission(file_mnt_idmap(file),\ninclude/linux/fs.h-2697-\t\t\t\tfile_inode(file), mask);\n--\nsecurity/apparmor/domain.c=919=int apparmor_bprm_creds_for_exec(struct linux_binprm *bprm)\n--\nsecurity/apparmor/domain.c-928-\tbool unsafe = false;\nsecurity/apparmor/domain.c:929:\tvfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(bprm-\u003efile),\nsecurity/apparmor/domain.c-930-\t\t\t\t\t    file_inode(bprm-\u003efile));\n--\nsecurity/apparmor/file.c=483=static int __file_path_perm(const char *op, const struct cred *subj_cred,\n--\nsecurity/apparmor/file.c-489-\tstruct aa_perms perms = {};\nsecurity/apparmor/file.c:490:\tvfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(file),\nsecurity/apparmor/file.c-491-\t\t\t\t\t    file_inode(file));\n--\nsecurity/apparmor/lsm.c=461=static int apparmor_file_open(struct file *file)\n--\nsecurity/apparmor/lsm.c-484-\tif (!unconfined(label)) {\nsecurity/apparmor/lsm.c:485:\t\tstruct mnt_idmap *idmap = file_mnt_idmap(file);\nsecurity/apparmor/lsm.c-486-\t\tstruct inode *inode = file_inode(file);\n--\nsecurity/commoncap.c=763=static int get_file_caps(struct linux_binprm *bprm, const struct file *file,\n--\nsecurity/commoncap.c-784-\nsecurity/commoncap.c:785:\trc = get_vfs_caps_from_disk(file_mnt_idmap(file),\nsecurity/commoncap.c-786-\t\t\t\t    file-\u003ef_path.dentry, \u0026vcaps);\n--\nsecurity/integrity/ima/ima_main.c=254=static int process_measurement(struct file *file, const struct cred *cred,\n--\nsecurity/integrity/ima/ima_main.c-282-\t */\nsecurity/integrity/ima/ima_main.c:283:\taction = ima_get_action(file_mnt_idmap(file), inode, cred, prop,\nsecurity/integrity/ima/ima_main.c-284-\t\t\t\tmask, func, \u0026pcr, \u0026template_desc, NULL,\n--\nsecurity/integrity/ima/ima_main.c=543=static int ima_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot,\n--\nsecurity/integrity/ima/ima_main.c-563-\tinode = file_inode(vma-\u003evm_file);\nsecurity/integrity/ima/ima_main.c:564:\taction = ima_get_action(file_mnt_idmap(vma-\u003evm_file), inode,\nsecurity/integrity/ima/ima_main.c-565-\t\t\t\tcurrent_cred(), \u0026prop, MAY_EXEC, MMAP_CHECK,\nsecurity/integrity/ima/ima_main.c-566-\t\t\t\t\u0026pcr, \u0026template, NULL, NULL);\nsecurity/integrity/ima/ima_main.c:567:\taction |= ima_get_action(file_mnt_idmap(vma-\u003evm_file), inode,\nsecurity/integrity/ima/ima_main.c-568-\t\t\t\t current_cred(), \u0026prop, MAY_EXEC,\n--\nsecurity/integrity/ima/ima_main.c=1176=void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)\n--\nsecurity/integrity/ima/ima_main.c-1184-\nsecurity/integrity/ima/ima_main.c:1185:\tprocess_buffer_measurement(file_mnt_idmap(fd_file(f)), file_inode(fd_file(f)),\nsecurity/integrity/ima/ima_main.c-1186-\t\t\t\t   buf, size, \"kexec-cmdline\", KEXEC_CMDLINE, 0,\n"
}

gemini-3.1-pro-preview

null

null

							input: 12717
							output: 20
							thoughts: 183
						

**Analyzing the Madvise and Mincore Implementation**

Okay, so I'm looking into these changes, specifically in `mm/madvise.c` and `mm/mincore.c`. My initial focus is on the functions `madvise_pageout`, `madvise_cold_or_pageout_pte_range`, and `do_mincore`. I need to understand how these pieces fit together. Hmm, `madvise_pageout` is static, which is interesting. That means it's likely called within the same file. Let's see... it looks like it's invoked by `madvise_vma_behavior` or perhaps directly by `do_madvise`. I should probably confirm that.

Alright, time to dive deeper. I'll need to check the implementations of both `madvise_pageout` and `do_mincore` carefully. I recall `do_mincore` is the core functionality behind the `sys_mincore` system call, so that's a good starting point. Now, to trace back the call stack for `madvise_pageout`. I suspect I'll find it within `madvise_vma_behavior` or some similar higher-level function in `mm/madvise.c`. Okay, let's open that file and get to work.

{
  "Expression": "madvise_pageout"
}

{
  "Output": "mm/madvise.c=595=static long madvise_cold(struct madvise_behavior *madv_behavior)\n--\nmm/madvise.c-610-\nmm/madvise.c:611:static void madvise_pageout_page_range(struct mmu_gather *tlb,\nmm/madvise.c-612-\t\tstruct vm_area_struct *vma,\n--\nmm/madvise.c-625-\nmm/madvise.c:626:static long madvise_pageout(struct madvise_behavior *madv_behavior)\nmm/madvise.c-627-{\n--\nmm/madvise.c-645-\ttlb_gather_mmu(\u0026tlb, madv_behavior-\u003emm);\nmm/madvise.c:646:\tmadvise_pageout_page_range(\u0026tlb, vma, \u0026madv_behavior-\u003erange);\nmm/madvise.c-647-\ttlb_finish_mmu(\u0026tlb);\n--\nmm/madvise.c=1338=static int madvise_vma_behavior(struct madvise_behavior *madv_behavior)\n--\nmm/madvise.c-1356-\tcase MADV_PAGEOUT:\nmm/madvise.c:1357:\t\treturn madvise_pageout(madv_behavior);\nmm/madvise.c-1358-\tcase MADV_FREE:\n"
}

gemini-3.1-pro-preview

null

null

							input: 13596
							output: 22
							thoughts: 106
						

**Analyzing Pageout and Memory Management**

Okay, so I'm honing in on the key symbols related to the pageout process – `do_mincore` and `madvise_pageout`. But hold on, I need to expand my scope slightly. Looking deeper, `madvise_cold_or_pageout_pte_range` seems important as well, because it calls `can_do_file_pageout`. Now, I recall that `madvise_cold_or_pageout_pte_range` functions as a page walk callback. I should probably focus on `can_do_file_pageout` itself. I’ll navigate to `mm/madvise.c` to see what's actually happening within that function.

{
  "Expression": "can_do_file_pageout"
}

{
  "Output": "mm/madvise.c=281=static long madvise_willneed(struct madvise_behavior *madv_behavior)\n--\nmm/madvise.c-328-\nmm/madvise.c:329:static inline bool can_do_file_pageout(struct vm_area_struct *vma)\nmm/madvise.c-330-{\n--\nmm/madvise.c=353=static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,\n--\nmm/madvise.c-373-\tpageout_anon_only_filter = pageout \u0026\u0026 !vma_is_anonymous(vma) \u0026\u0026\nmm/madvise.c:374:\t\t\t\t\t!can_do_file_pageout(vma);\nmm/madvise.c-375-\n--\nmm/madvise.c=626=static long madvise_pageout(struct madvise_behavior *madv_behavior)\n--\nmm/madvise.c-639-\t */\nmm/madvise.c:640:\tif (!vma_is_anonymous(vma) \u0026\u0026 (!can_do_file_pageout(vma) \u0026\u0026\nmm/madvise.c-641-\t\t\t\t(vma-\u003evm_flags \u0026 VM_MAYSHARE)))\n"
}

gemini-3.1-pro-preview

null

null

							input: 14232
							output: 20
							thoughts: 69
						

Okay, let's break this down.

**Focusing My Analysis of Memory Management**

Right, so I'm thinking about where to start digging deeper into some memory management tools and behaviors. I've got a couple of key areas to concentrate on. It looks like `madvise_pageout` and `madvise_cold_or_pageout_pte_range` are excellent starting points for understanding the specifics of pageout mechanisms and how the kernel interacts with them. Those functions likely hold the core logic I'm looking for.

Then there's `mincore.c`, and specifically `do_mincore`. That seems like an obvious function to study. This would be central to understanding how the `mincore` system call works to determine resident memory pages. I think I will study how that system call is implemented, so that I have a better understanding of how the user accesses memory residence information.

And finally, something else that caught my eye is `can_do_cachestat` in `mm/filemap.c`. That function *could* be a related area for consideration as well, since that file is related to `filemap`, which relates to cached file data that would also be paged out or managed differently in the system. I should investigate that, to see if there are any interesting implications on pageout/cachestat.

{
  "Expression": "can_do_cachestat"
}

{
  "Output": "mm/filemap.c=4602=static void filemap_cachestat(struct address_space *mapping,\n--\nmm/filemap.c-4702- */\nmm/filemap.c:4703:static inline bool can_do_cachestat(struct file *f)\nmm/filemap.c-4704-{\n--\nmm/filemap.c=4746=SYSCALL_DEFINE4(cachestat, unsigned int, fd,\n--\nmm/filemap.c-4766-\nmm/filemap.c:4767:\tif (!can_do_cachestat(fd_file(f)))\nmm/filemap.c-4768-\t\treturn -EPERM;\n"
}

gemini-3.1-pro-preview

null

null

							input: 14797
							output: 23
							thoughts: 275
						

**My Line of Reasoning for Identifying Relevant Functions and Configurations**

Okay, let's break this down. First, I need to figure out the key functions related to cache statistics. Is it `sys_cachestat`, `__x64_sys_cachestat`, or perhaps `filemap_cachestat`? No, wait a minute, `can_do_cachestat` is *called* in `SYSCALL_DEFINE4(cachestat, ...)` which *is* `sys_cachestat`. That settles it.

So, the symbols to focus on are `do_mincore`, `madvise_pageout`, and `madvise_cold_or_pageout_pte_range`.

Ah, but the original thought had `sys_cachestat` as a syscall, and syzkaller usually attacks syscalls directly. So maybe the focus should be `filemap_cachestat`? No, no, `can_do_cachestat` *is* within `sys_cachestat`, so that's the path. I'll just keep the prior list of functions: `do_mincore`, `madvise_pageout`, and `madvise_cold_or_pageout_pte_range`.

Now, configurations. I have to see if there are any relevant configurations at play. Idmapped mounts are enabled by `CONFIG_USER_NS` and `CONFIG_MULTIUSER`. But those are general and not specific to this patch.

Is there a specific configuration for `madvise` or `mincore`? Perhaps `CONFIG_ADVISE_SYSCALLS`? Time to dig into `mm/Kconfig` or `init/Kconfig` and find out.

{
  "Expression": "config ADVISE_SYSCALLS"
}

{
  "Output": "init/Kconfig=1937=config IO_URING_MOCK_FILE\n--\ninit/Kconfig-1947-\ninit/Kconfig:1948:config ADVISE_SYSCALLS\ninit/Kconfig-1949-\tbool \"Enable madvise/fadvise syscalls\" if EXPERT\n"
}

gemini-3.1-pro-preview

null

null

							input: 15555
							output: 17
							thoughts: 32
						

Okay, here's my take on those thoughts, framed as my own:

**Considering Kernel Configuration for Memory Management**

Right, so I'm evaluating kernel configurations and immediately, I'm thinking, including `ADVISE_SYSCALLS` is a solid move. It provides important hints to the kernel about how we expect to access memory and that's generally a performance win. But that leads me to think about `mincore`, and how it relates. Is there a specific configuration option dedicated to enabling or disabling `mincore` functionality? I need to quickly determine whether the current build includes that ability and if not, how easily it can be introduced. That kind of insight directly influences my next steps in the build and optimization process.

no matches

{
  "Expression": "config MINCORE"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 15773
							output: 18
							thoughts: 16
						

Okay, here's my interpretation of that thought process, from an expert's perspective:

**Diving into the Build Process**

Alright, so I need to understand how `mincore.o` is being built. My first instinct is to go straight to the `mm/Makefile`. That's where the memory management-related object files and their dependencies will be defined, or at least linked. I'm assuming it's under the `mm/` directory, which is pretty standard for kernel code. Makes sense to start there, as the makefiles orchestrate the compilation and linking process, so it's the obvious entry point to understand the build recipe for a specific object file. Let's see what the makefile tells us.

{
  "Expression": "mincore\\.o"
}

{
  "Output": "mm/Makefile=36=mmu-y\t\t\t:= nommu.o\nmm/Makefile:37:mmu-$(CONFIG_MMU)\t:= highmem.o memory.o mincore.o \\\nmm/Makefile-38-\t\t\t   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \\\n"
}

gemini-3.1-pro-preview

null

null

							input: 16058
							output: 16
							thoughts: 45
						

Okay, here's my take on those thoughts, framed as my own reasoning:

**Checking Kernel Configuration Dependencies**

Alright, let's see... the build system is complaining about `mincore.o`, and it seems like the issue boils down to `CONFIG_MMU`. But hold on, isn't `CONFIG_MMU` a given for all of our target platforms? I'm pretty sure it is. We've always needed a memory management unit, so that should be enabled by default. I need to double-check my assumptions, though, and I'll make a mental note to confirm it in our base config files. It's usually the simple things that trip us up.

Now, what was that other module the build was grumbling about? Oh yeah, `cachestat`. Does `cachestat` rely on any specific configuration options? I should quickly scan the Kconfig to see if there's a relevant option I've overlooked, because I am fairly certain I have never dealt with it before.

{
  "Expression": "cachestat"
}

{
  "Output": "MAINTAINERS=5713=S:\tMaintained\nMAINTAINERS:5714:F:\ttools/testing/selftests/cachestat/test_cachestat.c\nMAINTAINERS-5715-\n--\narch/alpha/kernel/syscalls/syscall.tbl-492-560\tcommon\tset_mempolicy_home_node\t\tsys_ni_syscall\narch/alpha/kernel/syscalls/syscall.tbl:493:561\tcommon\tcachestat\t\t\tsys_cachestat\narch/alpha/kernel/syscalls/syscall.tbl-494-562\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/arm/tools/syscall.tbl-467-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/arm/tools/syscall.tbl:468:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/arm/tools/syscall.tbl-469-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/arm64/tools/syscall_32.tbl-464-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/arm64/tools/syscall_32.tbl:465:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/arm64/tools/syscall_32.tbl-466-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/m68k/kernel/syscalls/syscall.tbl-452-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/m68k/kernel/syscalls/syscall.tbl:453:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/m68k/kernel/syscalls/syscall.tbl-454-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/microblaze/kernel/syscalls/syscall.tbl-458-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/microblaze/kernel/syscalls/syscall.tbl:459:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/microblaze/kernel/syscalls/syscall.tbl-460-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/mips/kernel/syscalls/syscall_n32.tbl-391-450\tn32\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/mips/kernel/syscalls/syscall_n32.tbl:392:451\tn32\tcachestat\t\t\tsys_cachestat\narch/mips/kernel/syscalls/syscall_n32.tbl-393-452\tn32\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/mips/kernel/syscalls/syscall_n64.tbl-367-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/mips/kernel/syscalls/syscall_n64.tbl:368:451\tn64\tcachestat\t\t\tsys_cachestat\narch/mips/kernel/syscalls/syscall_n64.tbl-369-452\tn64\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/mips/kernel/syscalls/syscall_o32.tbl-440-450\to32\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/mips/kernel/syscalls/syscall_o32.tbl:441:451\to32\tcachestat\t\t\tsys_cachestat\narch/mips/kernel/syscalls/syscall_o32.tbl-442-452\to32\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/parisc/kernel/syscalls/syscall.tbl-451-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/parisc/kernel/syscalls/syscall.tbl:452:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/parisc/kernel/syscalls/syscall.tbl-453-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/powerpc/kernel/syscalls/syscall.tbl-543-450 \tnospu\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/powerpc/kernel/syscalls/syscall.tbl:544:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/powerpc/kernel/syscalls/syscall.tbl-545-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/s390/kernel/syscalls/syscall.tbl-379-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/s390/kernel/syscalls/syscall.tbl:380:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/s390/kernel/syscalls/syscall.tbl-381-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/sh/kernel/syscalls/syscall.tbl-456-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/sh/kernel/syscalls/syscall.tbl:457:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/sh/kernel/syscalls/syscall.tbl-458-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/sparc/kernel/syscalls/syscall.tbl-498-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/sparc/kernel/syscalls/syscall.tbl:499:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/sparc/kernel/syscalls/syscall.tbl-500-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\narch/x86/entry/syscalls/syscall_32.tbl-458-450\ti386\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/x86/entry/syscalls/syscall_32.tbl:459:451\ti386\tcachestat\t\tsys_cachestat\narch/x86/entry/syscalls/syscall_32.tbl-460-452\ti386\tfchmodat2\t\tsys_fchmodat2\n--\narch/x86/entry/syscalls/syscall_64.tbl-377-450\tcommon\tset_mempolicy_home_node\tsys_set_mempolicy_home_node\narch/x86/entry/syscalls/syscall_64.tbl:378:451\tcommon\tcachestat\t\tsys_cachestat\narch/x86/entry/syscalls/syscall_64.tbl-379-452\tcommon\tfchmodat2\t\tsys_fchmodat2\n--\narch/xtensa/kernel/syscalls/syscall.tbl-423-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\narch/xtensa/kernel/syscalls/syscall.tbl:424:451\tcommon\tcachestat\t\t\tsys_cachestat\narch/xtensa/kernel/syscalls/syscall.tbl-425-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ninclude/linux/syscalls.h=74=enum landlock_rule_type;\ninclude/linux/syscalls.h:75:struct cachestat_range;\ninclude/linux/syscalls.h:76:struct cachestat;\ninclude/linux/syscalls.h-77-struct statmount;\n--\ninclude/linux/syscalls.h=995=asmlinkage long sys_set_mempolicy_home_node(unsigned long start, unsigned long len,\n--\ninclude/linux/syscalls.h-997-\t\t\t\t\t    unsigned long flags);\ninclude/linux/syscalls.h:998:asmlinkage long sys_cachestat(unsigned int fd,\ninclude/linux/syscalls.h:999:\t\tstruct cachestat_range __user *cstat_range,\ninclude/linux/syscalls.h:1000:\t\tstruct cachestat __user *cstat, unsigned int flags);\ninclude/linux/syscalls.h-1001-asmlinkage long sys_map_shadow_stack(unsigned long addr, unsigned long size, unsigned int flags);\n--\ninclude/uapi/asm-generic/unistd.h=814=__SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node)\ninclude/uapi/asm-generic/unistd.h:815:#define __NR_cachestat 451\ninclude/uapi/asm-generic/unistd.h:816:__SYSCALL(__NR_cachestat, sys_cachestat)\ninclude/uapi/asm-generic/unistd.h-817-#define __NR_fchmodat2 452\n--\ninclude/uapi/linux/mman.h-45-\ninclude/uapi/linux/mman.h:46:struct cachestat_range {\ninclude/uapi/linux/mman.h-47-\t__u64 off;\n--\ninclude/uapi/linux/mman.h-50-\ninclude/uapi/linux/mman.h:51:struct cachestat {\ninclude/uapi/linux/mman.h-52-\t__u64 nr_cache;\n--\ninit/Kconfig=2041=config CACHESTAT_SYSCALL\ninit/Kconfig:2042:\tbool \"Enable cachestat() system call\" if EXPERT\ninit/Kconfig-2043-\tdefault y\ninit/Kconfig-2044-\thelp\ninit/Kconfig:2045:\t  Enable the cachestat system call, which queries the page cache\ninit/Kconfig-2046-\t  statistics of a file (number of cached pages, dirty pages,\n--\nkernel/sys_ni.c=195=COND_SYSCALL(set_mempolicy_home_node);\nkernel/sys_ni.c:196:COND_SYSCALL(cachestat);\nkernel/sys_ni.c-197-COND_SYSCALL(mseal);\n--\nmm/filemap.c=4587=EXPORT_SYMBOL_GPL(filemap_invalidate_inode);\n--\nmm/filemap.c-4590-/**\nmm/filemap.c:4591: * filemap_cachestat() - compute the page cache statistics of a mapping\nmm/filemap.c-4592- * @mapping:\tThe mapping to compute the statistics for.\n--\nmm/filemap.c-4594- * @last_index:\tThe final page index (inclusive).\nmm/filemap.c:4595: * @cs:\tthe cachestat struct to write the result to.\nmm/filemap.c-4596- *\n--\nmm/filemap.c-4601- */\nmm/filemap.c:4602:static void filemap_cachestat(struct address_space *mapping,\nmm/filemap.c:4603:\t\tpgoff_t first_index, pgoff_t last_index, struct cachestat *cs)\nmm/filemap.c-4604-{\n--\nmm/filemap.c-4702- */\nmm/filemap.c:4703:static inline bool can_do_cachestat(struct file *f)\nmm/filemap.c-4704-{\n--\nmm/filemap.c-4712-/*\nmm/filemap.c:4713: * The cachestat(2) system call.\nmm/filemap.c-4714- *\nmm/filemap.c:4715: * cachestat() returns the page cache statistics of a file in the\nmm/filemap.c-4716- * bytes range specified by `off` and `len`: number of cached pages,\n--\nmm/filemap.c-4734- *\nmm/filemap.c:4735: * Because the status of a page can change after cachestat() checks it\nmm/filemap.c-4736- * but before it returns to the application, the returned values may\n--\nmm/filemap.c-4745- */\nmm/filemap.c:4746:SYSCALL_DEFINE4(cachestat, unsigned int, fd,\nmm/filemap.c:4747:\t\tstruct cachestat_range __user *, cstat_range,\nmm/filemap.c:4748:\t\tstruct cachestat __user *, cstat, unsigned int, flags)\nmm/filemap.c-4749-{\n--\nmm/filemap.c-4751-\tstruct address_space *mapping;\nmm/filemap.c:4752:\tstruct cachestat_range csr;\nmm/filemap.c:4753:\tstruct cachestat cs;\nmm/filemap.c-4754-\tpgoff_t first_index, last_index;\n--\nmm/filemap.c-4759-\tif (copy_from_user(\u0026csr, cstat_range,\nmm/filemap.c:4760:\t\t\tsizeof(struct cachestat_range)))\nmm/filemap.c-4761-\t\treturn -EFAULT;\n--\nmm/filemap.c-4766-\nmm/filemap.c:4767:\tif (!can_do_cachestat(fd_file(f)))\nmm/filemap.c-4768-\t\treturn -EPERM;\n--\nmm/filemap.c-4775-\t\tcsr.len == 0 ? ULONG_MAX : (csr.off + csr.len - 1) \u003e\u003e PAGE_SHIFT;\nmm/filemap.c:4776:\tmemset(\u0026cs, 0, sizeof(struct cachestat));\nmm/filemap.c-4777-\tmapping = fd_file(f)-\u003ef_mapping;\nmm/filemap.c:4778:\tfilemap_cachestat(mapping, first_index, last_index, \u0026cs);\nmm/filemap.c-4779-\nmm/filemap.c:4780:\tif (copy_to_user(cstat, \u0026cs, sizeof(struct cachestat)))\nmm/filemap.c-4781-\t\treturn -EFAULT;\n--\nmm/workingset.c=430=bool workingset_test_recent(void *shadow, bool file, bool *workingset,\n--\nmm/workingset.c-482-\t * Note that workingset_test_recent() itself might be called in RCU read\nmm/workingset.c:483:\t * section (for e.g, in cachestat) - these callers need to skip flushing\nmm/workingset.c-484-\t * stats (via the flush argument).\n--\nscripts/syscall.tbl-393-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\nscripts/syscall.tbl:394:451\tcommon\tcachestat\t\t\tsys_cachestat\nscripts/syscall.tbl-395-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/include/uapi/asm-generic/unistd.h=814=__SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node)\ntools/include/uapi/asm-generic/unistd.h:815:#define __NR_cachestat 451\ntools/include/uapi/asm-generic/unistd.h:816:__SYSCALL(__NR_cachestat, sys_cachestat)\ntools/include/uapi/asm-generic/unistd.h-817-#define __NR_fchmodat2 452\n--\ntools/include/uapi/linux/mman.h-45-\ntools/include/uapi/linux/mman.h:46:struct cachestat_range {\ntools/include/uapi/linux/mman.h-47-\t__u64 off;\n--\ntools/include/uapi/linux/mman.h-50-\ntools/include/uapi/linux/mman.h:51:struct cachestat {\ntools/include/uapi/linux/mman.h-52-\t__u64 nr_cache;\n--\ntools/perf/arch/alpha/entry/syscalls/syscall.tbl-492-560\tcommon\tset_mempolicy_home_node\t\tsys_ni_syscall\ntools/perf/arch/alpha/entry/syscalls/syscall.tbl:493:561\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/alpha/entry/syscalls/syscall.tbl-494-562\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/arm/entry/syscalls/syscall.tbl-467-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/arm/entry/syscalls/syscall.tbl:468:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/arm/entry/syscalls/syscall.tbl-469-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl-464-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl:465:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl-466-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/mips/entry/syscalls/syscall_n64.tbl-367-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/mips/entry/syscalls/syscall_n64.tbl:368:451\tn64\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/mips/entry/syscalls/syscall_n64.tbl-369-452\tn64\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl-451-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl:452:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl-453-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl-543-450 \tnospu\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl:544:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl-545-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/s390/entry/syscalls/syscall.tbl-379-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/s390/entry/syscalls/syscall.tbl:380:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/s390/entry/syscalls/syscall.tbl-381-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/sh/entry/syscalls/syscall.tbl-456-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/sh/entry/syscalls/syscall.tbl:457:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/sh/entry/syscalls/syscall.tbl-458-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl-498-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl:499:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl-500-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl-458-450\ti386\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl:459:451\ti386\tcachestat\t\tsys_cachestat\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl-460-452\ti386\tfchmodat2\t\tsys_fchmodat2\n--\ntools/perf/arch/x86/entry/syscalls/syscall_64.tbl-377-450\tcommon\tset_mempolicy_home_node\tsys_set_mempolicy_home_node\ntools/perf/arch/x86/entry/syscalls/syscall_64.tbl:378:451\tcommon\tcachestat\t\tsys_cachestat\ntools/perf/arch/x86/entry/syscalls/syscall_64.tbl-379-452\tcommon\tfchmodat2\t\tsys_fchmodat2\n--\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl-423-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl:424:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl-425-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/scripts/syscall.tbl-393-450\tcommon\tset_mempolicy_home_node\t\tsys_set_mempolicy_home_node\ntools/scripts/syscall.tbl:394:451\tcommon\tcachestat\t\t\tsys_cachestat\ntools/scripts/syscall.tbl-395-452\tcommon\tfchmodat2\t\t\tsys_fchmodat2\n--\ntools/testing/selftests/Makefile=7=TARGETS += breakpoints\ntools/testing/selftests/Makefile:8:TARGETS += cachestat\ntools/testing/selftests/Makefile-9-TARGETS += capabilities\n--\ntools/testing/selftests/cachestat/.gitignore-1-# SPDX-License-Identifier: GPL-2.0-only\ntools/testing/selftests/cachestat/.gitignore:2:test_cachestat\ntools/testing/selftests/cachestat/.gitignore-3-tmpshmcstat\n--\ntools/testing/selftests/cachestat/Makefile-1-# SPDX-License-Identifier: GPL-2.0\ntools/testing/selftests/cachestat/Makefile:2:TEST_GEN_PROGS := test_cachestat\ntools/testing/selftests/cachestat/Makefile-3-\n--\ntools/testing/selftests/cachestat/test_cachestat.c=23=static const char * const dev_files[] = {\n--\ntools/testing/selftests/cachestat/test_cachestat.c-27-\ntools/testing/selftests/cachestat/test_cachestat.c:28:void print_cachestat(struct cachestat *cs)\ntools/testing/selftests/cachestat/test_cachestat.c-29-{\ntools/testing/selftests/cachestat/test_cachestat.c-30-\tksft_print_msg(\ntools/testing/selftests/cachestat/test_cachestat.c:31:\t\"Using cachestat: Cached: %llu, Dirty: %llu, Writeback: %llu, Evicted: %llu, Recently Evicted: %llu\\n\",\ntools/testing/selftests/cachestat/test_cachestat.c-32-\tcs-\u003enr_cache, cs-\u003enr_dirty, cs-\u003enr_writeback,\n--\ntools/testing/selftests/cachestat/test_cachestat.c=106=static bool is_on_tmpfs(int fd)\n--\ntools/testing/selftests/cachestat/test_cachestat.c-117- * Open/create the file at filename, (optionally) write random data to it\ntools/testing/selftests/cachestat/test_cachestat.c:118: * (exactly num_pages), then test the cachestat syscall on this file.\ntools/testing/selftests/cachestat/test_cachestat.c-119- *\n--\ntools/testing/selftests/cachestat/test_cachestat.c-122- */\ntools/testing/selftests/cachestat/test_cachestat.c:123:static int test_cachestat(const char *filename, bool write_random, bool create,\ntools/testing/selftests/cachestat/test_cachestat.c-124-\t\t\t  bool test_fsync, unsigned long num_pages,\n--\ntools/testing/selftests/cachestat/test_cachestat.c-130-\tlong syscall_ret;\ntools/testing/selftests/cachestat/test_cachestat.c:131:\tstruct cachestat cs;\ntools/testing/selftests/cachestat/test_cachestat.c:132:\tstruct cachestat_range cs_range = { 0, filesize };\ntools/testing/selftests/cachestat/test_cachestat.c-133-\n--\ntools/testing/selftests/cachestat/test_cachestat.c-151-\ntools/testing/selftests/cachestat/test_cachestat.c:152:\tsyscall_ret = syscall(__NR_cachestat, fd, \u0026cs_range, \u0026cs, 0);\ntools/testing/selftests/cachestat/test_cachestat.c-153-\n--\ntools/testing/selftests/cachestat/test_cachestat.c-161-\t} else {\ntools/testing/selftests/cachestat/test_cachestat.c:162:\t\tprint_cachestat(\u0026cs);\ntools/testing/selftests/cachestat/test_cachestat.c-163-\n--\ntools/testing/selftests/cachestat/test_cachestat.c-179-\t\t} else {\ntools/testing/selftests/cachestat/test_cachestat.c:180:\t\t\tsyscall_ret = syscall(__NR_cachestat, fd, \u0026cs_range, \u0026cs, 0);\ntools/testing/selftests/cachestat/test_cachestat.c-181-\n--\ntools/testing/selftests/cachestat/test_cachestat.c-185-\t\t\tif (!syscall_ret) {\ntools/testing/selftests/cachestat/test_cachestat.c:186:\t\t\t\tprint_cachestat(\u0026cs);\ntools/testing/selftests/cachestat/test_cachestat.c-187-\n--\ntools/testing/selftests/cachestat/test_cachestat.c=209=const char *file_type_str(enum file_type type)\n--\ntools/testing/selftests/cachestat/test_cachestat.c-221-\ntools/testing/selftests/cachestat/test_cachestat.c:222:bool run_cachestat_test(enum file_type type)\ntools/testing/selftests/cachestat/test_cachestat.c-223-{\n--\ntools/testing/selftests/cachestat/test_cachestat.c-227-\tsize_t compute_len = PS * 512;\ntools/testing/selftests/cachestat/test_cachestat.c:228:\tstruct cachestat_range cs_range = { PS, compute_len };\ntools/testing/selftests/cachestat/test_cachestat.c-229-\tchar *filename = \"tmpshmcstat\", *map;\ntools/testing/selftests/cachestat/test_cachestat.c:230:\tstruct cachestat cs;\ntools/testing/selftests/cachestat/test_cachestat.c-231-\tbool ret = true;\n--\ntools/testing/selftests/cachestat/test_cachestat.c-275-\t}\ntools/testing/selftests/cachestat/test_cachestat.c:276:\tsyscall_ret = syscall(__NR_cachestat, fd, \u0026cs_range, \u0026cs, 0);\ntools/testing/selftests/cachestat/test_cachestat.c-277-\n--\ntools/testing/selftests/cachestat/test_cachestat.c-282-\t} else {\ntools/testing/selftests/cachestat/test_cachestat.c:283:\t\tprint_cachestat(\u0026cs);\ntools/testing/selftests/cachestat/test_cachestat.c-284-\t\tif (cs.nr_cache + cs.nr_evicted != num_pages) {\n--\ntools/testing/selftests/cachestat/test_cachestat.c=297=int main(void)\n--\ntools/testing/selftests/cachestat/test_cachestat.c-302-\ntools/testing/selftests/cachestat/test_cachestat.c:303:\tret = syscall(__NR_cachestat, -1, NULL, NULL, 0);\ntools/testing/selftests/cachestat/test_cachestat.c-304-\tif (ret == -1 \u0026\u0026 errno == ENOSYS)\ntools/testing/selftests/cachestat/test_cachestat.c:305:\t\tksft_exit_skip(\"cachestat syscall not available\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-306-\n--\ntools/testing/selftests/cachestat/test_cachestat.c-319-\ntools/testing/selftests/cachestat/test_cachestat.c:320:\t\tif (test_cachestat(dev_filename, false, false, false,\ntools/testing/selftests/cachestat/test_cachestat.c-321-\t\t\t4, O_RDONLY, 0400) == KSFT_PASS)\ntools/testing/selftests/cachestat/test_cachestat.c:322:\t\t\tksft_test_result_pass(\"cachestat works with %s\\n\", dev_filename);\ntools/testing/selftests/cachestat/test_cachestat.c-323-\t\telse {\ntools/testing/selftests/cachestat/test_cachestat.c:324:\t\t\tksft_test_result_fail(\"cachestat fails with %s\\n\", dev_filename);\ntools/testing/selftests/cachestat/test_cachestat.c-325-\t\t\tret = 1;\n--\ntools/testing/selftests/cachestat/test_cachestat.c-328-\ntools/testing/selftests/cachestat/test_cachestat.c:329:\tif (test_cachestat(\"tmpfilecachestat\", true, true,\ntools/testing/selftests/cachestat/test_cachestat.c-330-\t\tfalse, 4, O_CREAT | O_RDWR, 0600) == KSFT_PASS)\ntools/testing/selftests/cachestat/test_cachestat.c:331:\t\tksft_test_result_pass(\"cachestat works with a normal file\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-332-\telse {\ntools/testing/selftests/cachestat/test_cachestat.c:333:\t\tksft_test_result_fail(\"cachestat fails with normal file\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-334-\t\tret = 1;\n--\ntools/testing/selftests/cachestat/test_cachestat.c-336-\ntools/testing/selftests/cachestat/test_cachestat.c:337:\tswitch (test_cachestat(\"tmpfilecachestat\", true, true,\ntools/testing/selftests/cachestat/test_cachestat.c-338-\t\ttrue, 4, O_CREAT | O_RDWR, 0600)) {\ntools/testing/selftests/cachestat/test_cachestat.c-339-\tcase KSFT_FAIL:\ntools/testing/selftests/cachestat/test_cachestat.c:340:\t\tksft_test_result_fail(\"cachestat fsync fails with normal file\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-341-\t\tret = KSFT_FAIL;\n--\ntools/testing/selftests/cachestat/test_cachestat.c-343-\tcase KSFT_PASS:\ntools/testing/selftests/cachestat/test_cachestat.c:344:\t\tksft_test_result_pass(\"cachestat fsync works with a normal file\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-345-\t\tbreak;\ntools/testing/selftests/cachestat/test_cachestat.c-346-\tcase KSFT_SKIP:\ntools/testing/selftests/cachestat/test_cachestat.c:347:\t\tksft_test_result_skip(\"tmpfilecachestat is on tmpfs\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-348-\t\tbreak;\n--\ntools/testing/selftests/cachestat/test_cachestat.c-350-\ntools/testing/selftests/cachestat/test_cachestat.c:351:\tif (run_cachestat_test(FILE_SHMEM))\ntools/testing/selftests/cachestat/test_cachestat.c:352:\t\tksft_test_result_pass(\"cachestat works with a shmem file\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-353-\telse {\ntools/testing/selftests/cachestat/test_cachestat.c:354:\t\tksft_test_result_fail(\"cachestat fails with a shmem file\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-355-\t\tret = 1;\n--\ntools/testing/selftests/cachestat/test_cachestat.c-357-\ntools/testing/selftests/cachestat/test_cachestat.c:358:\tif (run_cachestat_test(FILE_MMAP))\ntools/testing/selftests/cachestat/test_cachestat.c:359:\t\tksft_test_result_pass(\"cachestat works with a mmap file\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-360-\telse {\ntools/testing/selftests/cachestat/test_cachestat.c:361:\t\tksft_test_result_fail(\"cachestat fails with a mmap file\\n\");\ntools/testing/selftests/cachestat/test_cachestat.c-362-\t\tret = 1;\n"
}

gemini-3.1-pro-preview

null

null

							input: 25468
							output: 21
							thoughts: 226
						

**Analyzing the Cachestat Patch**

Okay, so I'm looking at this patch and immediately, `CONFIG_CACHESTAT_SYSCALL` pops out. That's the config for `cachestat`, right? Let's quickly verify that. I'll check `init/Kconfig` to confirm that `CACHESTAT_SYSCALL` is there. Ah, yes, and it looks like it's enabled by default, but it's always good to be explicit. Good to include it in the mental checklist.

Wait, a bit further down, it looks like this patch is touching `can_do_cachestat` within `mm/filemap.c`. That tells me the `sys_cachestat` system call is probably the key focus point here. I should add `sys_cachestat` to my list of FocusSymbols. I'll make a note for future analysis.

Hmm, a change here. It looks like the patch is replacing `inode_owner_or_capable(file_mnt_idmap(f), file_inode(f))` with `file_owner_or_capable(f)` in `mm/filemap.c`. That's interesting, but I don't see any obvious functional change at first glance. It looks like a simple refactoring because `file_owner_or_capable(f)` seems to be *defined* as exactly `inode_owner_or_capable(file_mnt_idmap(f), file_inode(f))`. Just to be absolutely sure, I'll quickly double-check that definition in `include/linux/fs.h` before I move on.

{
  "Expression": "file_owner_or_capable"
}

{
  "Output": "include/linux/fs.h=2442=static inline struct mnt_idmap *file_mnt_idmap(const struct file *file)\n--\ninclude/linux/fs.h-2446-\ninclude/linux/fs.h:2447:static inline bool file_owner_or_capable(const struct file *file)\ninclude/linux/fs.h-2448-{\n--\nmm/filemap.c=4703=static inline bool can_do_cachestat(struct file *f)\n--\nmm/filemap.c-4706-\t\treturn true;\nmm/filemap.c:4707:\tif (file_owner_or_capable(f))\nmm/filemap.c-4708-\t\treturn true;\n--\nmm/madvise.c=329=static inline bool can_do_file_pageout(struct vm_area_struct *vma)\n--\nmm/madvise.c-338-\t */\nmm/madvise.c:339:\treturn file_owner_or_capable(vma-\u003evm_file) ||\nmm/madvise.c-340-\t       file_permission(vma-\u003evm_file, MAY_WRITE) == 0;\n--\nmm/mincore.c=218=static inline bool can_do_mincore(struct vm_area_struct *vma)\n--\nmm/mincore.c-229-\t */\nmm/mincore.c:230:\treturn file_owner_or_capable(vma-\u003evm_file) ||\nmm/mincore.c-231-\t       file_permission(vma-\u003evm_file, MAY_WRITE) == 0;\n"
}

gemini-3.1-pro-preview

null

null

							input: 26502
							output: 18
							thoughts: 731
						

**My Analysis of this Patch**

Okay, let's break this down. From the code diff, it looks like a refactoring in `mm/filemap.c`, but a functional change in `mm/madvise.c` and `mm/mincore.c`. Specifically, they're correcting the handling of idmapped mounts. They're replacing the use of `&nop_mnt_idmap` with the correct `file_mnt_idmap(vma->vm_file)`. This means `sys_cachestat` *isn't* functionally altered, but `do_mincore` and `madvise_pageout` *are*.

So, my focus symbols need to reflect these functional changes. I'll need to include `do_mincore` and `madvise_pageout`. Wait, isn't `madvise_pageout` static? Yes, but it's reachable through `sys_madvise`, so that's fine. Similarly, `do_mincore` is static but reachable through `sys_mincore`. I should also include `madvise_cold_or_pageout_pte_range` as it's directly involved in the fix.

The key configuration to enable here is `ADVISE_SYSCALLS`. `CONFIG_USER_NS` and `CONFIG_MULTIUSER` are likely prerequisites, but they're fairly standard and can be assumed. I'll stick with just enabling `ADVISE_SYSCALLS`.

Okay, summarizing my findings:

*   **WorthFuzzing:** True - This patch fixes a bug in core memory management logic related to idmapped mounts, so it's critical to fuzz.
*   **Reasoning:** The patch corrects the handling of idmapped mounts in `madvise` and `mincore` by replacing a placeholder idmap with the correct mount's idmap, making a functional change.
*   **FocusSymbols:** `do_mincore`, `madvise_pageout`, `madvise_cold_or_pageout_pte_range`
*   **EnableConfigs:** `ADVISE_SYSCALLS`

I need to double-check that `MADV_COLD` actually uses `can_do_file_pageout`. Ah, in `mm/madvise.c`, there's a check `pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) && !can_do_file_pageout(vma);`, so it does! That confirms my choice of focus symbols. `madvise_cold_or_pageout_pte_range` is definitely relevant. This is good. I think I'm done here.

{
  "Expression": "do_mincore"
}

{
  "Output": "mm/mincore.c=163=static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,\n--\nmm/mincore.c-217-\nmm/mincore.c:218:static inline bool can_do_mincore(struct vm_area_struct *vma)\nmm/mincore.c-219-{\n--\nmm/mincore.c=234=static const struct mm_walk_ops mincore_walk_ops = {\n--\nmm/mincore.c-245- */\nmm/mincore.c:246:static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)\nmm/mincore.c-247-{\n--\nmm/mincore.c-255-\tend = min(vma-\u003evm_end, addr + (pages \u003c\u003c PAGE_SHIFT));\nmm/mincore.c:256:\tif (!can_do_mincore(vma)) {\nmm/mincore.c-257-\t\tunsigned long pages = DIV_ROUND_UP(end - addr, PAGE_SIZE);\n--\nmm/mincore.c=291=SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,\n--\nmm/mincore.c-325-\t\tmmap_read_lock(current-\u003emm);\nmm/mincore.c:326:\t\tretval = do_mincore(start, min(pages, PAGE_SIZE), tmp);\nmm/mincore.c-327-\t\tmmap_read_unlock(current-\u003emm);\n"
}

gemini-3.1-pro-preview

null

null

							input: 28253
							output: 129
							thoughts: 128
						

Okay, let's break this down.

**My Thinking on `mincore` Implementation and Configuration**

Right, so `do_mincore`... that's the main function that calls `can_do_mincore`. That's a key starting point. I need to remember that. And the other FocusSymbols I'm concerned with are `madvise_pageout` and `madvise_cold_or_pageout_pte_range`, which are likely related to pageout functionality.

Now, the `ADVISE_SYSCALLS` EnableConfig is certainly relevant here.

Hmm, I recall there wasn't a dedicated config specifically for `mincore` itself. It looks like it gets built indirectly, based on whether `CONFIG_MMU` is enabled. That makes sense, given the memory management implications.

Alright, I think I've got a solid grasp of the relevant functions, configuration, and dependencies. I'm ready to move on and set the results accordingly.

{
  "EnableConfigs": [
    "ADVISE_SYSCALLS"
  ],
  "FocusSymbols": [
    "do_mincore",
    "madvise_pageout",
    "madvise_cold_or_pageout_pte_range"
  ],
  "Reasoning": "The patch fixes a bug where idmapped mounts were not properly handled in `madvise` and `mincore` by replacing `\u0026nop_mnt_idmap` with the actual mount idmap of the file. This is a functional change in core memory management logic.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "ADVISE_SYSCALLS"
  ],
  "FocusSymbols": [
    "do_mincore",
    "madvise_pageout",
    "madvise_cold_or_pageout_pte_range"
  ],
  "Reasoning": "The patch fixes a bug where idmapped mounts were not properly handled in `madvise` and `mincore` by replacing `\u0026nop_mnt_idmap` with the actual mount idmap of the file. This is a functional change in core memory management logic.",
  "WorthFuzzing": true
}