syzbot

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BUG: KCSAN: data-race in list_lru_add / list_lru_count_node

write to 0xffff88812a5e69a8 of 8 bytes by task 30270 on cpu 0:
 list_lru_add+0x256/0x460 mm/list_lru.c:140
 d_lru_add+0xa9/0xf0 fs/dcache.c:404
 retain_dentry fs/dcache.c:653 [inline]
 dput+0x3f4/0x700 fs/dcache.c:854
 path_put_conditional fs/namei.c:863 [inline]
 follow_managed+0x205/0x720 fs/namei.c:1359
 walk_component+0x525/0x9a0 fs/namei.c:1921
 lookup_last fs/namei.c:2391 [inline]
 path_lookupat.isra.0+0x129/0x2e0 fs/namei.c:2436
 filename_lookup+0x145/0x2b0 fs/namei.c:2466
 user_path_at_empty+0x47/0x60 fs/namei.c:2746
 user_path_at include/linux/namei.h:58 [inline]
 do_faccessat+0x12b/0x470 fs/open.c:398
 __do_sys_access fs/open.c:450 [inline]
 __se_sys_access fs/open.c:448 [inline]
 __x64_sys_access+0x3c/0x50 fs/open.c:448
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812a5e69a8 of 8 bytes by task 30268 on cpu 1:
 list_lru_count_node+0x32/0x50 mm/list_lru.c:205
 list_lru_count include/linux/list_lru.h:132 [inline]
 shrink_dcache_sb+0x143/0x1c0 fs/dcache.c:1243
 reconfigure_super+0x318/0x570 fs/super.c:940
 do_remount fs/namespace.c:2553 [inline]
 do_mount+0x1120/0x14d0 fs/namespace.c:3098
 __do_sys_mount fs/namespace.c:3316 [inline]
 __se_sys_mount fs/namespace.c:3293 [inline]
 __x64_sys_mount+0x12b/0x1a0 fs/namespace.c:3293
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 30268 Comm: syz-executor.2 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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