KCSAN: data-race in atime_needs_update / inode_set_ctime_to

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in atime_needs_update / inode_set_ctime_to_ts fs	6				1	430d	430d	0/29	auto-obsoleted due to no activity on 2025/08/02 17:48
upstream	KCSAN: data-race in atime_needs_update / inode_set_ctime_to_ts (3) fs	6				1	226d	226d	0/29	auto-obsoleted due to no activity on 2026/02/23 14:35

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BUG: KCSAN: data-race in atime_needs_update / inode_set_ctime_to_ts

write to 0xffff88811e1d5b20 of 4 bytes by task 3778 on cpu 0:
 inode_set_ctime_to_ts+0x84/0x170 fs/inode.c:2715
 inode_set_ctime_current+0x1d6/0x770 fs/inode.c:2778
 shmem_xattr_handler_set+0x1ac/0x220 mm/shmem.c:4336
 __vfs_setxattr+0x2e6/0x310 fs/xattr.c:200
 __vfs_setxattr_noperm+0xe8/0x410 fs/xattr.c:234
 __vfs_setxattr_locked+0x1af/0x1d0 fs/xattr.c:295
 vfs_setxattr+0x132/0x270 fs/xattr.c:321
 do_setxattr fs/xattr.c:636 [inline]
 filename_setxattr+0x1ad/0x400 fs/xattr.c:665
 path_setxattrat+0x2c9/0x310 fs/xattr.c:713
 __do_sys_lsetxattr fs/xattr.c:754 [inline]
 __se_sys_lsetxattr fs/xattr.c:750 [inline]
 __x64_sys_lsetxattr+0x71/0x90 fs/xattr.c:750
 x64_sys_call+0x287b/0x3000 arch/x86/include/generated/asm/syscalls_64.h:190
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811e1d5b20 of 4 bytes by task 3301 on cpu 1:
 inode_get_ctime_nsec include/linux/fs.h:1869 [inline]
 inode_get_ctime include/linux/fs.h:1875 [inline]
 relatime_need_update fs/inode.c:2018 [inline]
 atime_needs_update+0x333/0x3e0 fs/inode.c:2158
 touch_atime+0x4a/0x340 fs/inode.c:2173
 do_readlinkat+0x134/0x320 fs/stat.c:589
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:610
 x64_sys_call+0x28de/0x3000 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x22fee768 -> 0x24301468

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3301 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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