syzbot

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BUG: KCSAN: data-race in link_path_walk / shrink_dentry_list

read-write to 0xffff8881d1601840 of 4 bytes by task 21839 on cpu 0:
 d_shrink_del fs/dcache.c:448 [inline]
 shrink_dentry_list+0x1c7/0x380 fs/dcache.c:1188
 shrink_dcache_sb+0x165/0x290 fs/dcache.c:1321
 reconfigure_super+0x3ef/0x580 fs/super.c:1121
 do_remount fs/namespace.c:2884 [inline]
 path_mount+0x969/0xb30 fs/namespace.c:3656
 do_mount fs/namespace.c:3677 [inline]
 __do_sys_mount fs/namespace.c:3886 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3863
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3863
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881d1601840 of 4 bytes by task 21831 on cpu 1:
 __d_entry_type include/linux/dcache.h:386 [inline]
 d_can_lookup include/linux/dcache.h:401 [inline]
 link_path_walk+0x4fc/0x7e0 fs/namei.c:2339
 path_lookupat+0x72/0x2a0 fs/namei.c:2482
 filename_lookup+0x126/0x300 fs/namei.c:2512
 kern_path+0x39/0x110 fs/namei.c:2610
 do_loopback+0x65/0x2d0 fs/namespace.c:2613
 path_mount+0x3cb/0xb30 fs/namespace.c:3658
 do_mount fs/namespace.c:3677 [inline]
 __do_sys_mount fs/namespace.c:3886 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3863
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3863
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00280400 -> 0x00200000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 21831 Comm: syz-executor.1 Not tainted 6.7.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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