syzbot

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BUG: KCSAN: data-race in lookup_fast / shrink_dentry_list

read-write to 0xffff888106bda480 of 4 bytes by task 561 on cpu 1:
 d_shrink_del fs/dcache.c:449 [inline]
 shrink_dentry_list+0x226/0x3d0 fs/dcache.c:1067
 shrink_dcache_sb+0x165/0x290 fs/dcache.c:1195
 reconfigure_super+0x3ef/0x580 fs/super.c:1054
 do_remount fs/namespace.c:2892 [inline]
 path_mount+0x969/0xb30 fs/namespace.c:3671
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3875
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3875
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888106bda480 of 4 bytes by task 559 on cpu 0:
 d_revalidate fs/namei.c:861 [inline]
 lookup_fast+0xd9/0x290 fs/namei.c:1642
 walk_component+0x3f/0x230 fs/namei.c:1997
 lookup_last fs/namei.c:2458 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2482
 filename_lookup+0x126/0x300 fs/namei.c:2511
 user_path_at_empty+0x42/0x110 fs/namei.c:2920
 user_path_at include/linux/namei.h:57 [inline]
 do_mount fs/namespace.c:3689 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x24b/0x2d0 fs/namespace.c:3875
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3875
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00290400 -> 0x00210000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 559 Comm: syz-executor.3 Tainted: G        W          6.7.0-syzkaller-12991-g7a396820222d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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EXT4-fs (sda1): re-mounted 5941fea2-f5fa-4b4e-b5ef-9af118b27b95 r/w. Quota mode: none.