syzbot

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BUG: KCSAN: data-race in lookup_fast / shrink_dentry_list

read-write to 0xffff88810a362b40 of 4 bytes by task 3160 on cpu 1:
 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:853
 shrink_slab_memcg mm/vmscan.c:922 [inline]
 shrink_slab+0x2bc/0x520 mm/vmscan.c:1001
 shrink_node_memcgs mm/vmscan.c:6439 [inline]
 shrink_node+0xaf5/0x14f0 mm/vmscan.c:6473
 shrink_zones mm/vmscan.c:6711 [inline]
 do_try_to_free_pages+0x40d/0xc80 mm/vmscan.c:6773
 try_to_free_mem_cgroup_pages+0x1e2/0x480 mm/vmscan.c:7088
 reclaim_high+0xca/0x110 mm/memcontrol.c:2403
 mem_cgroup_handle_over_high+0x8c/0x1a0 mm/memcontrol.c:2588
 resume_user_mode_work include/linux/resume_user_mode.h:58 [inline]
 exit_to_user_mode_loop+0x99/0xe0 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0x6a/0xa0 kernel/entry/common.c:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:296
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88810a362b40 of 4 bytes by task 12815 on cpu 0:
 d_revalidate fs/namei.c:856 [inline]
 lookup_fast+0xd9/0x290 fs/namei.c:1635
 walk_component+0x3f/0x230 fs/namei.c:1990
 lookup_last fs/namei.c:2451 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2475
 filename_lookup+0x126/0x300 fs/namei.c:2504
 user_path_at_empty+0x42/0x110 fs/namei.c:2877
 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: 0 PID: 12815 Comm: syz-executor.3 Not tainted 6.3.0-rc2-syzkaller-00050-g9c1bec9c0b08 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
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