syzbot

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BUG: KCSAN: data-race in dentry_lru_isolate / link_path_walk

write to 0xffff88810298e900 of 4 bytes by task 735 on cpu 0:
 d_lru_isolate fs/dcache.c:442 [inline]
 dentry_lru_isolate+0x9f/0x280 fs/dcache.c:1199
 __list_lru_walk_one+0xfb/0x320 mm/list_lru.c:222
 list_lru_walk_one+0x75/0xc0 mm/list_lru.c:266
 list_lru_shrink_walk include/linux/list_lru.h:195 [inline]
 prune_dcache_sb+0x67/0xa0 fs/dcache.c:1253
 super_cache_scan+0x23e/0x2e0 fs/super.c:105
 do_shrink_slab+0x26e/0x4d0 mm/vmscan.c:512
 shrink_slab+0xea/0x1c0 mm/vmscan.c:673
 shrink_node_memcgs+0x28a/0x420 mm/vmscan.c:2655
 shrink_node+0x9ad/0x1170 mm/vmscan.c:2770
 kswapd_shrink_node mm/vmscan.c:3513 [inline]
 balance_pgdat+0x662/0xc00 mm/vmscan.c:3671
 kswapd+0x1f3/0x300 mm/vmscan.c:3928
 kthread+0x1d0/0x1f0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88810298e900 of 4 bytes by task 1029 on cpu 1:
 __d_entry_type include/linux/dcache.h:394 [inline]
 d_can_lookup include/linux/dcache.h:409 [inline]
 link_path_walk+0x4d7/0x780 fs/namei.c:2279
 path_lookupat+0x7b/0x570 fs/namei.c:2420
 filename_lookup+0xff/0x390 fs/namei.c:2454
 user_path_at_empty+0x3b/0x50 fs/namei.c:2734
 user_path_at include/linux/namei.h:60 [inline]
 do_faccessat+0x260/0x510 fs/open.c:425
 __do_sys_access fs/open.c:484 [inline]
 __se_sys_access fs/open.c:482 [inline]
 __x64_sys_access+0x33/0x40 fs/open.c:482
 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: 1 PID: 1029 Comm: systemd-udevd Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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