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BUG: KCSAN: data-race in drop_nlink / vfs_getattr_nosec

write to 0xffff888105f3b5f8 of 4 bytes by task 16934 on cpu 1:
 drop_nlink+0x37/0x90 fs/inode.c:305
 shmem_rmdir+0x42/0x70 mm/shmem.c:2981
 vfs_rmdir+0x13b/0x2c0 fs/namei.c:3895
 do_rmdir+0x14a/0x2e0 fs/namei.c:3958
 __do_sys_rmdir fs/namei.c:3976 [inline]
 __se_sys_rmdir fs/namei.c:3974 [inline]
 __x64_sys_rmdir+0x2c/0x30 fs/namei.c:3974
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888105f3b5f8 of 4 bytes by task 16947 on cpu 0:
 generic_fillattr fs/stat.c:49 [inline]
 vfs_getattr_nosec+0x1c1/0x2f0 fs/stat.c:108
 vfs_getattr fs/stat.c:142 [inline]
 vfs_fstat fs/stat.c:164 [inline]
 __do_sys_newfstat fs/stat.c:404 [inline]
 __se_sys_newfstat+0x94/0x2c0 fs/stat.c:401
 __x64_sys_newfstat+0x2d/0x40 fs/stat.c:401
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16947 Comm: systemd-udevd Not tainted 5.13.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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