WARNING: lock held when returning to user space in blk_mq_freeze_queue_nomemsave

Status: moderation: reported on 2026/10/08 15:51
Subsystems: block
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+96a17b2abf8665f6903b@syzkaller.appspotmail.com
First crash: 4d03h, last: 4d03h
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ID Workflow Result Correct Bug Created Started Finished Revision
60536f61 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ WARNING: lock held when returning to user space in blk_mq_freeze_queue_nomemsave 2026/10/05 18:17 2026/10/05 18:17 2026/10/05 19:46 1995e6c7

Sample crash report:
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WARNING: lock held when returning to user space!
syzkaller #0 Not tainted
------------------------------------------------
syz.3.475/8501 is leaving the kernel with locks still held!
locks held by syz.3.475/8501: 2, last CPU#0:
 #0: ffff88803aec1c50 (&q->q_usage_counter(io)#223){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:206
 #1: ffff88803aec1c88 (&q->q_usage_counter(queue)#207){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:206

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/04 15:45 upstream 6addb4f38557 57bbd979 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: lock held when returning to user space in blk_mq_freeze_queue_nomemsave
* Struck through repros no longer work on HEAD.