[moderation] [net?] [nfs?] WARNING: refcount bug in cache_clean

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c2e6a872bde9 netpoll: Fix race condition in netpoll_owner_..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1415e1ef180000
kernel config: https://syzkaller.appspot.com/x/.config?x=15dda165e1d20cf1
dashboard link: https://syzkaller.appspot.com/bug?extid=c31346016beea569adba
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [Dai...@oracle.com an...@kernel.org chuck...@oracle.com da...@davemloft.net edum...@google.com jla...@kernel.org ko...@netapp.com ku...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@vger.kernel.org ne...@suse.de net...@vger.kernel.org pab...@redhat.com t...@talpey.com trond.m...@hammerspace.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/256b2a473dd0/disk-c2e6a872.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b98d2ea5cc29/vmlinux-c2e6a872.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9c13648621f1/bzImage-c2e6a872.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c31346...@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 5179 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 1 PID: 5179 Comm: kworker/1:6 Not tainted 6.9.0-rc5-syzkaller-01459-gc2e6a872bde9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: events_power_efficient do_cache_clean
RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Code: e0 4b 1f 8c e8 07 fe a8 fc 90 0f 0b 90 90 eb 99 e8 7b 81 e6 fc c6 05 3d 3e e4 0a 01 90 48 c7 c7 40 4c 1f 8c e8 e7 fd a8 fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 58 81 e6 fc c6 05 17 3e e4 0a 01 90
RSP: 0018:ffffc900039afa68 EFLAGS: 00010246
RAX: 238e75778706bd00 RBX: ffff88807dd63958 RCX: ffff8880219e1e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff81589b62 R09: fffffbfff1c39b6c
R10: dffffc0000000000 R11: fffffbfff1c39b6c R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8a967a40 R15: ffff88807dd63958
FS: 0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020011038 CR3: 00000000234c2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__refcount_sub_and_test include/linux/refcount.h:275 [inline]
__refcount_dec_and_test include/linux/refcount.h:307 [inline]
refcount_dec_and_test include/linux/refcount.h:325 [inline]
kref_put include/linux/kref.h:64 [inline]
cache_put include/linux/sunrpc/cache.h:213 [inline]
sunrpc_end_cache_remove_entry net/sunrpc/cache.c:96 [inline]
cache_clean+0x9de/0xa30 net/sunrpc/cache.c:491
do_cache_clean+0x22/0xb0 net/sunrpc/cache.c:508
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>


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