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BUG: KCSAN: data-race in atime_needs_update / touch_atime

read to 0xffff888104df80f0 of 4 bytes by task 6164 on cpu 0:
 atime_needs_update+0x25f/0x3e0 fs/inode.c:-1
 touch_atime+0x4a/0x300 fs/inode.c:2312
 file_accessed include/linux/fs.h:2272 [inline]
 shmem_file_read_iter+0x3ed/0x4b0 mm/shmem.c:3394
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x699/0x7c0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 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+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff888104df80f0 of 4 bytes by task 6154 on cpu 1:
 inode_set_atime_to_ts include/linux/fs.h:1621 [inline]
 inode_update_atime fs/inode.c:2157 [inline]
 inode_update_time fs/inode.c:2221 [inline]
 generic_update_time fs/inode.c:2254 [inline]
 touch_atime+0x1cb/0x300 fs/inode.c:2332
 file_accessed include/linux/fs.h:2272 [inline]
 shmem_file_read_iter+0x3ed/0x4b0 mm/shmem.c:3394
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x699/0x7c0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 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+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x2286153e -> 0x26b232bd

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6154 Comm: udevd Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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udevd[6154]: inotify_add_watch(7, /dev/loop5p1, 10) failed: No such file or directory