syzbot

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BUG: KCSAN: data-race in __dentry_kill / step_into

read-write to 0xffff888100541300 of 4 bytes by task 22580 on cpu 1:
 dentry_unlist fs/dcache.c:548 [inline]
 __dentry_kill+0x228/0x4b0 fs/dcache.c:617
 shrink_kill fs/dcache.c:1048 [inline]
 shrink_dentry_list+0x1bc/0x3e0 fs/dcache.c:1075
 shrink_dcache_sb+0x165/0x2a0 fs/dcache.c:1195
 reconfigure_super+0x3fe/0x5a0 fs/super.c:1049
 do_remount fs/namespace.c:2892 [inline]
 path_mount+0x96e/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
 x64_sys_call+0x2591/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888100541300 of 4 bytes by task 18907 on cpu 0:
 __d_entry_type include/linux/dcache.h:397 [inline]
 d_is_symlink include/linux/dcache.h:427 [inline]
 step_into+0x12f/0x810 fs/namei.c:1847
 open_last_lookups fs/namei.c:3589 [inline]
 path_openat+0x10fc/0x1d80 fs/namei.c:3796
 do_filp_open+0xf7/0x200 fs/namei.c:3826
 do_sys_openat2+0xab/0x120 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1432
 x64_sys_call+0x2cad/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00200000 -> 0x00008000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18907 Comm: syz-executor.3 Not tainted 6.9.0-rc4-syzkaller-00031-g96fca68c4fbf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.