[moderation] [fs?] KCSAN: data-race in ___d_drop / __d_lookup (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fda5e3f28400 Merge tag 'trace-v6.13-rc7-2' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14f591f8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d9abea8414eb570
dashboard link: https://syzkaller.appspot.com/bug?extid=9be250f274c7dbc4ce3a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4d5f6816092c/disk-fda5e3f2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1ded03944f78/vmlinux-fda5e3f2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c917646ad908/bzImage-fda5e3f2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9be250...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in ___d_drop / __d_lookup

write to 0xffff8881065bcb50 of 8 bytes by task 11 on cpu 0:
__hlist_bl_del include/linux/list_bl.h:128 [inline]
___d_drop+0xe1/0x200 fs/dcache.c:523
__d_drop fs/dcache.c:530 [inline]
d_invalidate+0x54/0x1c0 fs/dcache.c:1607
proc_invalidate_siblings_dcache+0x1db/0x2b0 fs/proc/inode.c:142
proc_sys_invalidate_dcache fs/proc/proc_sysctl.c:289 [inline]
start_unregistering fs/proc/proc_sysctl.c:316 [inline]
drop_sysctl_table+0xbb/0x260 fs/proc/proc_sysctl.c:1513
drop_sysctl_table+0x1cd/0x260 fs/proc/proc_sysctl.c:1520
unregister_sysctl_table+0x30/0x50 fs/proc/proc_sysctl.c:1538
unregister_net_sysctl_table+0x15/0x20 net/sysctl_net.c:177
xfrm6_net_sysctl_exit net/ipv6/xfrm6_policy.c:233 [inline]
xfrm6_net_exit+0x3e/0x90 net/ipv6/xfrm6_policy.c:267
ops_exit_list net/core/net_namespace.c:172 [inline]
cleanup_net+0x47b/0x860 net/core/net_namespace.c:648
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3317
worker_thread+0x51d/0x6f0 kernel/workqueue.c:3398
kthread+0x1d1/0x210 kernel/kthread.c:389
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff8881065bcb50 of 8 bytes by task 3037 on cpu 1:
hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
d_unhashed include/linux/dcache.h:354 [inline]
__d_lookup+0xf1/0x370 fs/dcache.c:2341
lookup_fast+0x4c/0x2a0 fs/namei.c:1749
walk_component fs/namei.c:2108 [inline]
link_path_walk+0x464/0x820 fs/namei.c:2477
path_openat+0x1af/0x1fa0 fs/namei.c:3983
do_filp_open+0x107/0x230 fs/namei.c:4014
do_sys_openat2+0xab/0x120 fs/open.c:1402
do_sys_open fs/open.c:1417 [inline]
__do_sys_openat fs/open.c:1433 [inline]
__se_sys_openat fs/open.c:1428 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1428
x64_sys_call+0x2b30/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88810651cf08 -> 0xffff8881065bc608

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3037 Comm: dhcpcd Not tainted 6.13.0-rc7-syzkaller-00191-gfda5e3f28400 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.