syzbot

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BUG: KCSAN: data-race in fill_mg_cmtime / shmem_symlink

write to 0xffff8881036aa9a4 of 4 bytes by task 3291 on cpu 0:
 inode_set_mtime_to_ts include/linux/fs.h:1708 [inline]
 shmem_symlink+0x344/0x390 mm/shmem.c:4144
 vfs_symlink+0xca/0x1d0 fs/namei.c:4671
 do_symlinkat+0xe1/0x350 fs/namei.c:4697
 __do_sys_symlink fs/namei.c:4718 [inline]
 __se_sys_symlink fs/namei.c:4716 [inline]
 __x64_sys_symlink+0x50/0x60 fs/namei.c:4716
 x64_sys_call+0x28b0/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881036aa9a4 of 4 bytes by task 3552 on cpu 1:
 inode_get_mtime_nsec include/linux/fs.h:1694 [inline]
 inode_get_mtime include/linux/fs.h:1700 [inline]
 fill_mg_cmtime+0x58/0x280 fs/stat.c:55
 generic_fillattr+0x241/0x330 fs/stat.c:99
 shmem_getattr+0x17b/0x200 mm/shmem.c:1249
 vfs_getattr_nosec fs/stat.c:208 [inline]
 vfs_getattr+0x172/0x1b0 fs/stat.c:246
 vfs_statx_path fs/stat.c:283 [inline]
 vfs_statx+0x12d/0x320 fs/stat.c:349
 vfs_fstatat+0xe4/0x130 fs/stat.c:368
 __do_sys_newfstatat fs/stat.c:532 [inline]
 __se_sys_newfstatat+0x58/0x260 fs/stat.c:526
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:526
 x64_sys_call+0x236d/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x12e37d4b -> 0x130630db

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3552 Comm: udevd Not tainted 6.14.0-rc7-syzkaller-00202-g183601b78a9b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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