syzbot

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BUG: KCSAN: data-race in drop_nlink / generic_fillattr

write to 0xffff888120fa7aa8 of 4 bytes by task 19314 on cpu 0:
 drop_nlink+0x37/0x90 fs/inode.c:304
 shmem_unlink+0x16f/0x190 mm/shmem.c:3021
 shmem_rename2+0x2f4/0x430 mm/shmem.c:3113
 vfs_rename+0x8c2/0xe30 fs/namei.c:4309
 do_renameat2+0x554/0x940 fs/namei.c:4456
 __do_sys_rename fs/namei.c:4502 [inline]
 __se_sys_rename fs/namei.c:4500 [inline]
 __x64_sys_rename+0x3a/0x40 fs/namei.c:4500
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120fa7aa8 of 4 bytes by task 19361 on cpu 1:
 generic_fillattr+0x74/0x180 fs/stat.c:41
 shmem_getattr+0x232/0x2c0 mm/shmem.c:1073
 vfs_getattr_nosec fs/stat.c:87 [inline]
 vfs_getattr fs/stat.c:124 [inline]
 vfs_statx_fd fs/stat.c:151 [inline]
 vfs_fstat include/linux/fs.h:3189 [inline]
 __do_sys_newfstat fs/stat.c:398 [inline]
 __se_sys_newfstat+0x1b6/0x510 fs/stat.c:395
 __x64_sys_newfstat+0x2d/0x40 fs/stat.c:395
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19361 Comm: systemd-udevd Not tainted 5.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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