syzbot

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BUG: KCSAN: data-race in drop_nlink / generic_fillattr

write to 0xffff88811de8ef48 of 4 bytes by task 4965 on cpu 0:
 drop_nlink+0x3d/0xa0 fs/inode.c:419
 __simple_unlink fs/libfs.c:794 [inline]
 simple_unlink+0x60/0x80 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 0xffff88811de8ef48 of 4 bytes by task 3302 on cpu 1:
 generic_fillattr+0xfb/0x340 fs/stat.c:91
 shmem_getattr+0x181/0x200 mm/shmem.c:1302
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr fs/stat.c:262 [inline]
 vfs_fstat fs/stat.c:281 [inline]
 __do_sys_newfstat fs/stat.c:551 [inline]
 __se_sys_newfstat+0x96/0x460 fs/stat.c:546
 __x64_sys_newfstat+0x31/0x40 fs/stat.c:546
 x64_sys_call+0x2773/0x3020 arch/x86/include/generated/asm/syscalls_64.h:6
 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: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3302 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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