syzbot

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BUG: KCSAN: data-race in __d_lookup_rcu / shrink_dentry_list

read to 0xffff8881335513c0 of 4 bytes by task 1831 on cpu 0:
 __d_lookup_rcu+0x14b/0x400 fs/dcache.c:2350
 lookup_fast+0xc1/0x360 fs/namei.c:1630
 walk_component+0x6d/0x360 fs/namei.c:2016
 lookup_last fs/namei.c:2475 [inline]
 path_lookupat+0x12d/0x3d0 fs/namei.c:2499
 filename_lookup+0x130/0x310 fs/namei.c:2528
 user_path_at_empty+0x3e/0x110 fs/namei.c:2851
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0xa3/0x3c0 fs/stat.c:221
 vfs_fstatat fs/stat.c:243 [inline]
 vfs_lstat include/linux/fs.h:3287 [inline]
 __do_sys_newlstat fs/stat.c:398 [inline]
 __se_sys_newlstat+0x5d/0x250 fs/stat.c:392
 __x64_sys_newlstat+0x2d/0x40 fs/stat.c:392
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff8881335513c0 of 4 bytes by task 16239 on cpu 1:
 shrink_dentry_list+0x127/0x540 fs/dcache.c:448
 shrink_dcache_sb+0x188/0x2d0 fs/dcache.c:1321
 reconfigure_super+0x146/0x540 fs/super.c:888
 do_remount fs/namespace.c:2656 [inline]
 path_mount+0x13f9/0x1c40 fs/namespace.c:3316
 do_mount fs/namespace.c:3337 [inline]
 __do_sys_mount fs/namespace.c:3545 [inline]
 __se_sys_mount+0x24b/0x2f0 fs/namespace.c:3522
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3522
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16239 Comm: syz-executor.5 Tainted: G        W         5.17.0-rc3-syzkaller-00048-ge3c85076d7a6-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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EXT4-fs (sda1): re-mounted. Quota mode: none.