syzbot

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BUG: KCSAN: data-race in lookup_fast / shrink_dentry_list

read-write to 0xffff888109a1a840 of 4 bytes by task 3068 on cpu 0:
 d_shrink_del fs/dcache.c:448 [inline]
 shrink_dentry_list+0x169/0x380 fs/dcache.c:1197
 prune_dcache_sb+0x81/0xb0 fs/dcache.c:1282
 super_cache_scan+0x26c/0x310 fs/super.c:104
 do_shrink_slab+0x2a0/0x640 mm/vmscan.c:911
 shrink_slab_memcg mm/vmscan.c:981 [inline]
 shrink_slab+0x2d6/0x650 mm/vmscan.c:1061
 shrink_node_memcgs mm/vmscan.c:6468 [inline]
 shrink_node+0xadf/0x1500 mm/vmscan.c:6501
 shrink_zones mm/vmscan.c:6736 [inline]
 do_try_to_free_pages+0x40d/0xc80 mm/vmscan.c:6798
 try_to_free_mem_cgroup_pages+0x1e2/0x480 mm/vmscan.c:7113
 reclaim_high+0xca/0x110 mm/memcontrol.c:2432
 mem_cgroup_handle_over_high+0x8c/0x1a0 mm/memcontrol.c:2617
 resume_user_mode_work include/linux/resume_user_mode.h:58 [inline]
 exit_to_user_mode_loop+0x9b/0xe0 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:297
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888109a1a840 of 4 bytes by task 4733 on cpu 1:
 d_revalidate fs/namei.c:858 [inline]
 lookup_fast+0xd9/0x290 fs/namei.c:1639
 walk_component+0x3f/0x230 fs/namei.c:1994
 lookup_last fs/namei.c:2455 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2479
 filename_lookup+0x126/0x300 fs/namei.c:2508
 user_path_at_empty+0x42/0x110 fs/namei.c:2907
 user_path_at include/linux/namei.h:57 [inline]
 __do_sys_chdir fs/open.c:551 [inline]
 __se_sys_chdir+0x4f/0x140 fs/open.c:545
 __x64_sys_chdir+0x1f/0x30 fs/open.c:545
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00280400 -> 0x00008000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4733 Comm: syz-executor.5 Not tainted 6.4.0-rc2-syzkaller-00015-g1b66c114d161 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
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