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BUG: KCSAN: data-race in generic_fillattr / touch_atime

read to 0xffff88811dae3958 of 4 bytes by task 10767 on cpu 0:
 inode_get_atime_nsec include/linux/fs.h:1611 [inline]
 inode_get_atime include/linux/fs.h:1617 [inline]
 generic_fillattr+0x172/0x340 fs/stat.c:96
 shmem_getattr+0x181/0x200 mm/shmem.c:1302
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr fs/stat.c:262 [inline]
 vfs_fstat fs/stat.c:281 [inline]
 __do_sys_newfstat fs/stat.c:551 [inline]
 __se_sys_newfstat+0x96/0x460 fs/stat.c:546
 __x64_sys_newfstat+0x31/0x40 fs/stat.c:546
 x64_sys_call+0x2773/0x3020 arch/x86/include/generated/asm/syscalls_64.h:6
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff88811dae3958 of 4 bytes by task 10799 on cpu 1:
 inode_set_atime_to_ts include/linux/fs.h:1626 [inline]
 inode_update_atime fs/inode.c:2098 [inline]
 inode_update_time fs/inode.c:2156 [inline]
 generic_update_time fs/inode.c:2189 [inline]
 touch_atime+0x1d7/0x330 fs/inode.c:2267
 file_accessed include/linux/fs.h:2264 [inline]
 shmem_file_read_iter+0x3f4/0x4b0 mm/shmem.c:3458
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x6c0/0x7f0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:717
 __do_sys_read fs/read_write.c:726 [inline]
 __se_sys_read fs/read_write.c:724 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:724
 x64_sys_call+0x2886/0x3020 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x044909fd -> 0x0468633f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10799 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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udevd[10799]: inotify_add_watch(7, /dev/loop0p2, 10) failed: No such file or directory