syzbot

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BUG: KCSAN: data-race in fill_mg_cmtime / simple_unlink

write to 0xffff8881040cd54c of 4 bytes by task 3303 on cpu 0:
 inode_set_mtime_to_ts include/linux/fs.h:1659 [inline]
 __simple_unlink fs/libfs.c:792 [inline]
 simple_unlink+0x54/0x80 fs/libfs.c:808
 shmem_unlink+0x12d/0x140 mm/shmem.c:4005
 shmem_rename2+0x18e/0x310 mm/shmem.c:4086
 vfs_rename+0x97f/0xad0 fs/namei.c:6026
 filename_renameat2+0x3b6/0x6e0 fs/namei.c:6144
 __do_sys_rename fs/namei.c:6188 [inline]
 __se_sys_rename+0x4a/0x1c0 fs/namei.c:6184
 __x64_sys_rename+0x31/0x40 fs/namei.c:6184
 x64_sys_call+0x2b3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881040cd54c of 4 bytes by task 3301 on cpu 1:
 inode_get_mtime_nsec include/linux/fs.h:1645 [inline]
 inode_get_mtime include/linux/fs.h:1651 [inline]
 fill_mg_cmtime+0x5b/0x270 fs/stat.c:55
 generic_fillattr+0x24a/0x340 fs/stat.c:99
 shmem_getattr+0x181/0x200 mm/shmem.c:1302
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr+0x48/0x60 fs/stat.c:262
 vfs_statx_path+0x28/0x140 fs/stat.c:299
 vfs_statx+0xc4/0x170 fs/stat.c:356
 vfs_fstatat+0x118/0x170 fs/stat.c:373
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat+0x55/0x3e0 fs/stat.c:532
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:532
 x64_sys_call+0x2c64/0x3020 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0bd79bbd -> 0x0bdaeb8d

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3301 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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