syzbot

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BUG: KCSAN: data-race in generic_fillattr / touch_atime

read to 0xffff8881074a7828 of 4 bytes by task 3550 on cpu 0:
 inode_get_atime_nsec include/linux/fs.h:1669 [inline]
 inode_get_atime include/linux/fs.h:1675 [inline]
 generic_fillattr+0x172/0x340 fs/stat.c:96
 shmem_getattr+0x181/0x200 mm/shmem.c:1262
 vfs_getattr_nosec+0x143/0x1e0 fs/stat.c:213
 vfs_getattr fs/stat.c:262 [inline]
 vfs_fstat fs/stat.c:281 [inline]
 __do_sys_newfstat fs/stat.c:555 [inline]
 __se_sys_newfstat+0x96/0x2e0 fs/stat.c:550
 __x64_sys_newfstat+0x31/0x40 fs/stat.c:550
 x64_sys_call+0x27e1/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:6
 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

write to 0xffff8881074a7828 of 4 bytes by task 3299 on cpu 1:
 inode_set_atime_to_ts include/linux/fs.h:1684 [inline]
 inode_update_timestamps fs/inode.c:2035 [inline]
 generic_update_time fs/inode.c:2057 [inline]
 inode_update_time fs/inode.c:2077 [inline]
 touch_atime+0x1e8/0x340 fs/inode.c:2149
 file_accessed include/linux/fs.h:2652 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3447
 new_sync_read fs/read_write.c:491 [inline]
 vfs_read+0x5cd/0x6f0 fs/read_write.c:572
 ksys_read+0xda/0x1a0 fs/read_write.c:715
 __do_sys_read fs/read_write.c:724 [inline]
 __se_sys_read fs/read_write.c:722 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:722
 x64_sys_call+0x2d77/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:1
 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: 0x0117f90e -> 0x013029d9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3299 Comm: udevd Not tainted 6.16.0-rc3-syzkaller-00042-g78f4e737a53e #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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udevd[3299]: inotify_add_watch(7, /dev/loop2p4, 10) failed: No such file or directory