syzbot

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BUG: KCSAN: data-race in drop_nlink / generic_fillattr

write to 0xffff888117f25af0 of 4 bytes by task 3475 on cpu 0:
 drop_nlink+0x3b/0x90 fs/inode.c:408
 shmem_unlink+0x154/0x170 mm/shmem.c:3990
 shmem_rename2+0x1d4/0x2c0 mm/shmem.c:4076
 vfs_rename+0x875/0x9c0 fs/namei.c:5069
 do_renameat2+0x6a3/0xa70 fs/namei.c:5226
 __do_sys_rename fs/namei.c:5273 [inline]
 __se_sys_rename fs/namei.c:5271 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:5271
 x64_sys_call+0x2b1c/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:83
 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 0xffff888117f25af0 of 4 bytes by task 3374 on cpu 1:
 generic_fillattr+0xf8/0x330 fs/stat.c:91
 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_fstat fs/stat.c:265 [inline]
 vfs_fstatat+0xa7/0x130 fs/stat.c:366
 __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: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3374 Comm: udevd Not tainted 6.14.0-rc6-syzkaller-00253-gcb82ca153949 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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