syzbot

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BUG: KCSAN: data-race in generic_fillattr / touch_atime

write to 0xffff88813a8aaf70 of 4 bytes by task 3295 on cpu 0:
 inode_set_atime_to_ts include/linux/fs.h:1672 [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+0x1e8/0x330 fs/inode.c:2149
 file_accessed include/linux/fs.h:2599 [inline]
 shmem_file_read_iter+0x459/0x520 mm/shmem.c:3444
 new_sync_read fs/read_write.c:489 [inline]
 vfs_read+0x5ca/0x6f0 fs/read_write.c:570
 ksys_read+0xda/0x1a0 fs/read_write.c:713
 __do_sys_read fs/read_write.c:722 [inline]
 __se_sys_read fs/read_write.c:720 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:720
 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+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88813a8aaf70 of 4 bytes by task 3530 on cpu 1:
 inode_get_atime_nsec include/linux/fs.h:1657 [inline]
 inode_get_atime include/linux/fs.h:1663 [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:210
 vfs_getattr fs/stat.c:259 [inline]
 vfs_fstat fs/stat.c:278 [inline]
 vfs_fstatat+0x11d/0x160 fs/stat.c:370
 __do_sys_newfstatat fs/stat.c:536 [inline]
 __se_sys_newfstatat+0x55/0x260 fs/stat.c:530
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:530
 x64_sys_call+0x2c22/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x28d5363a -> 0x291d2f51

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3530 Comm: udevd Not tainted 6.15.0-rc4-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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udevd[3530]: inotify_add_watch(7, /dev/loop0p3, 10) failed: No such file or directory