KCSAN: data-race in dentry_lru_isolate / do_sys

KCSAN: data-race in dentry_lru_isolate / do_sys_openat2
Status: auto-closed as invalid on 2020/10/29 03:02
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 303d, last: 303d

Sample crash report:

==================================================================
BUG: KCSAN: data-race in dentry_lru_isolate / do_sys_openat2

write to 0xffff888122081180 of 4 bytes by task 2485 on cpu 0:
 d_lru_isolate fs/dcache.c:442 [inline]
 dentry_lru_isolate+0x9f/0x200 fs/dcache.c:1166
 __list_lru_walk_one+0xfb/0x320 mm/list_lru.c:222
 list_lru_walk_one+0x75/0x90 mm/list_lru.c:266
 list_lru_shrink_walk include/linux/list_lru.h:195 [inline]
 prune_dcache_sb+0x67/0xa0 fs/dcache.c:1220
 super_cache_scan+0x23b/0x2d0 fs/super.c:105
 do_shrink_slab+0x286/0x5c0 mm/vmscan.c:513
 shrink_slab+0xea/0x1c0 mm/vmscan.c:674
 shrink_node_memcgs+0x270/0x410 mm/vmscan.c:2653
 shrink_node+0x9ed/0x1230 mm/vmscan.c:2768
 kswapd_shrink_node mm/vmscan.c:3511 [inline]
 balance_pgdat+0x675/0xc20 mm/vmscan.c:3669
 kswapd+0x1ef/0x370 mm/vmscan.c:3926
 kthread+0x20d/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff888122081180 of 4 bytes by task 5075 on cpu 1:
 fsnotify_parent include/linux/fsnotify.h:60 [inline]
 fsnotify_file include/linux/fsnotify.h:90 [inline]
 fsnotify_open include/linux/fsnotify.h:268 [inline]
 do_sys_openat2+0x425/0x500 fs/open.c:1173
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_open fs/open.c:1192 [inline]
 __se_sys_open fs/open.c:1188 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1188
 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: 5075 Comm: systemd-udevd Not tainted 5.9.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/09/24 02:56	upstream	c9c9e6a49f89	54289b08	.config	log	report			info