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INFO: task hung in nbd_queue_rq

Status: upstream: reported C repro on 2024/08/28 00:09
Subsystems: nbd
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+30c16035531e3248dcbc@syzkaller.appspotmail.com
First crash: 691d, last: 15h01m
Cause bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
9a6aefaa-c3da-4f36-b44c-7c92892b1a6c assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: task hung in nbd_queue_rq 2026/05/31 10:45 2026/05/31 10:45 2026/05/31 11:43 6b4a844333e83556da95d61d7f207e7ef5cd4bc6
14a37df9-1511-4a04-9d72-e7d393e82ab3 assessment-security 💥 INFO: task hung in nbd_queue_rq 2026/05/14 16:24 2026/05/14 16:24 2026/05/14 16:26 6ccb967e465e832a7bfd7a116ad00d52a0923a5d failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/b2c991dd12c8e740be546267eec0540442e14e66" "-s" "bzImage" "compile_commands.json"]: exit status 2 * * Restart config... * * * General architecture-dependent options * SMT (Hyperthreading) scheduler support (SCHED_SMT) [Y/?] y Cluster scheduler support (SCHED_CLUSTER) [Y/n/?] y Multi-Core Cache (MC) scheduler support (SCHED_MC) [Y/n/?] y Kprobes (KPROBES) [N/y/?] n Optimize very unlikely/likely branches (JUMP_LABEL) [Y/n/?] y Static key selftest (STATIC_KEYS_SELFTEST) [N/y/?] n Static call selftest (STATIC_CALL_SELFTEST) [N/y/?] n Enable seccomp to safely execute untrusted bytecode (SECCOMP) [Y/n/?] y Show seccomp filter cache status in /proc/pid/seccomp_cache (SECCOMP_CACHE_DEBUG) [N/y/?] n Stack Protector buffer overflow detection (STACKPROTECTOR) [Y/n/?] y Strong Stack Protector (STACKPROTECTOR_STRONG) [Y/n/?] y Link Time Optimization (LTO) > 1. None (LTO_NONE) choice[1]: 1 Enable Clang's AutoFDO build (EXPERIMENTAL) (AUTOFDO_CLANG) [N/y/?] (NEW) Error in reading or end of file. Enable Clang's Propeller build (PROPELLER_CLANG) [N/y/?] (NEW) Error in reading or end of file. Use Kernel Control Flow Integrity (kCFI) (CFI) [N/y/?] (NEW) Error in reading or end of file. Number of bits to use for ASLR of mmap base address (ARCH_MMAP_RND_BITS) [28] 28 Number of bits to use for ASLR of mmap base address for compatible applications (ARCH_MMAP_RND_COMPAT_BITS) [8] 8 MMU page size > 1. 4KiB pages (PAGE_SIZE_4KB) choice[1]: 1 Provide system calls for 32-bit time_t (COMPAT_32BIT_TIME) [Y/n/?] y Use a virtually-mapped stack (VMAP_STACK) [Y/n/?] y Support for randomizing kernel stack offset on syscall entry (RANDOMIZE_KSTACK_OFFSET) [Y/n/?] y Default state of kernel stack offset randomization (RANDOMIZE_KSTACK_OFFSET_DEFAULT) [N/y/?] n Locking event counts collection (LOCK_EVENT_COUNTS) [N/y/?] n * * Memory initialization * Initialize kernel stack variables at function entry 1. no automatic stack variable initialization (weakest) (INIT_STACK_NONE) 2. pattern-init everything (strongest) (INIT_STACK_ALL_PATTERN) > 3. zero-init everything (strongest and safest) (INIT_STACK_ALL_ZERO) choice[1-3?]: 3 Poison kernel stack before returning from syscalls (KSTACK_ERASE) [N/y/?] (NEW) Error in reading or end of file. Enable heap memory zeroing on allocation by default (INIT_ON_ALLOC_DEFAULT_ON) [Y/n/?] y Enable heap memory zeroing on free by default (INIT_ON_FREE_DEFAULT_ON) [N/y/?] n Enable register zeroing on function exit (ZERO_CALL_USED_REGS) [N/y/?] n * * Kernel hardening options * Randomize layout of sensitive kernel structures > 1. Disable structure layout randomization (RANDSTRUCT_NONE) 2. Fully randomize structure layout (RANDSTRUCT_FULL) (NEW) choice[1-2?]: Error in reading or end of file. /app/workdir/cache/src/74c832176fe15c88a2a67daecb81ddc348e5a912/sound/usb/mixer_s1810c.c:633:5: warning: stack frame size (2360) exceeds limit (2048) in 'snd_sc1810_init_mixer' [-Wframe-larger-than] 633 | int snd_sc1810_init_mixer(struct usb_mixer_interface *mixer) | ^ 1 warning generated. fatal error: error in backend: IO failure on output stream: No space left on device PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script. Stack dump: 0. Program arguments: /usr/bin/clang --target=x86_64-linux-gnu -fintegrated-as -Werror=unknown-warning-option -Werror=ignored-optimization-argument -Werror=option-ignored -Werror=unused-command-line-argument -fmacro-prefix-map=/app/workdir/cache/src/74c832176fe15c88a2a67daecb81ddc348e5a912/= -std=gnu11 -fshort-wchar -funsigned-char -fno-common -fno-PIE -fno-strict-aliasing -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -mno-sse4a -fcf-protection=branch -fno-jump-tables -m64 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387 -mstack-alignment=8 -mskip-rax-setup -march=x86-64 -mtune=generic -mno-red-zone -mcmod
▶ ▼ Discussions (13)
Title Replies (including bot) Last reply
[syzbot] Monthly nbd report (Apr 2026) 0 (1) 2026/04/22 09:08
[syzbot] Monthly nbd report (Mar 2026) 0 (1) 2026/03/23 10:49
[syzbot] Monthly nbd report (Feb 2026) 0 (1) 2026/02/19 08:59
[syzbot] Monthly nbd report (Dec 2025) 0 (1) 2025/12/05 13:52
[syzbot] Monthly nbd report (Nov 2025) 0 (1) 2025/11/04 14:21
[syzbot] Monthly nbd report (Oct 2025) 0 (1) 2025/10/06 17:29
[syzbot] Monthly nbd report (Sep 2025) 0 (1) 2025/09/03 12:36
[syzbot] Monthly nbd report (Jul 2025) 0 (1) 2025/07/02 13:32
[syzbot] Monthly nbd report (Jun 2025) 0 (1) 2025/06/03 11:07
[syzbot] Monthly nbd report (Jan 2025) 0 (1) 2025/01/27 11:15
[syzbot] Monthly nbd report (Dec 2024) 0 (1) 2024/12/25 10:07
[syzbot] [nbd?] INFO: task hung in nbd_queue_rq 0 (2) 2024/09/17 10:03
[syzbot] Monthly nbd report (Sep 2024) 0 (1) 2024/09/14 10:58
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: task hung in nbd_queue_rq 1 1 274d 274d 0/2 auto-obsoleted due to no activity on 2025/12/16 17:15
▶ ▼ Last patch testing requests (4)
Created Duration User Patch Repo Result
2025/06/03 12:45 36m retest repro net-next report log
2025/05/19 21:55 20m retest repro net report log
2025/03/08 08:01 26m retest repro net report log
2024/10/01 15:51 22m retest repro net-next report log

Sample crash report:
INFO: task udevd:5835 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:24280 pid:5835  tgid:5835  ppid:5178   task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7008
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 wait_for_reconnect drivers/block/nbd.c:1107 [inline]
 nbd_handle_cmd drivers/block/nbd.c:1149 [inline]
 nbd_queue_rq+0xc50/0x1080 drivers/block/nbd.c:1207
 blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
 __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
 blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
 blk_finish_plug block/blk-core.c:1257 [inline]
 __submit_bio+0x584/0x6c0 block/blk-core.c:649
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753
 submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884
 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
 submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821
 submit_bh fs/buffer.c:2826 [inline]
 block_read_full_folio+0x4c8/0x8e0 fs/buffer.c:2458
 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501
 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4101
 read_mapping_folio include/linux/pagemap.h:1028 [inline]
 read_part_sector+0xd1/0x370 block/partitions/core.c:723
 adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360
 check_partition block/partitions/core.c:142 [inline]
 blk_add_partitions block/partitions/core.c:590 [inline]
 bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694
 blkdev_get_whole+0x187/0x290 block/bdev.c:764
 bdev_open+0x2c7/0xe40 block/bdev.c:973
 blkdev_open+0x34e/0x4f0 block/fops.c:697
 do_dentry_open+0x6d8/0x1660 fs/open.c:949
 vfs_open+0x82/0x3f0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2cfaaa7407
RSP: 002b:00007ffd77793060 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f2cfb259880 RCX: 00007f2cfaaa7407
RDX: 00000000000a0800 RSI: 0000558305ce46b0 RDI: ffffffffffffff9c
RBP: 0000558305ce12c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000558305f27320
R13: 0000558305f1c8d0 R14: 0000000000000000 R15: 0000558305f27320
 </TASK>
INFO: task udevd:6567 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:24280 pid:6567  tgid:6567  ppid:5178   task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7008
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 wait_for_reconnect drivers/block/nbd.c:1107 [inline]
 nbd_handle_cmd drivers/block/nbd.c:1149 [inline]
 nbd_queue_rq+0xc50/0x1080 drivers/block/nbd.c:1207
 blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
 __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
 blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
 blk_finish_plug block/blk-core.c:1257 [inline]
 __submit_bio+0x584/0x6c0 block/blk-core.c:649
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753
 submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884
 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
 submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821
 submit_bh fs/buffer.c:2826 [inline]
 block_read_full_folio+0x4c8/0x8e0 fs/buffer.c:2458
 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501
 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4101
 read_mapping_folio include/linux/pagemap.h:1028 [inline]
 read_part_sector+0xd1/0x370 block/partitions/core.c:723
 adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360
 check_partition block/partitions/core.c:142 [inline]
 blk_add_partitions block/partitions/core.c:590 [inline]
 bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694
 blkdev_get_whole+0x187/0x290 block/bdev.c:764
 bdev_open+0x2c7/0xe40 block/bdev.c:973
 blkdev_open+0x34e/0x4f0 block/fops.c:697
 do_dentry_open+0x6d8/0x1660 fs/open.c:949
 vfs_open+0x82/0x3f0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2cfaaa7407
RSP: 002b:00007ffd77793060 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f2cfb259880 RCX: 00007f2cfaaa7407
RDX: 00000000000a0800 RSI: 0000558305f37180 RDI: ffffffffffffff9c
RBP: 0000558305ce12c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000558305f2fcf0
R13: 0000558305f1c8d0 R14: 0000000000000000 R15: 0000558305f2fcf0
 </TASK>
INFO: task udevd:6739 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:24280 pid:6739  tgid:6739  ppid:5178   task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7008
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 wait_for_reconnect drivers/block/nbd.c:1107 [inline]
 nbd_handle_cmd drivers/block/nbd.c:1149 [inline]
 nbd_queue_rq+0xc50/0x1080 drivers/block/nbd.c:1207
 blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
 __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
 blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
 blk_finish_plug block/blk-core.c:1257 [inline]
 __submit_bio+0x584/0x6c0 block/blk-core.c:649
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753
 submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884
 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
 submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821
 submit_bh fs/buffer.c:2826 [inline]
 block_read_full_folio+0x4c8/0x8e0 fs/buffer.c:2458
 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501
 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4101
 read_mapping_folio include/linux/pagemap.h:1028 [inline]
 read_part_sector+0xd1/0x370 block/partitions/core.c:723
 adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360
 check_partition block/partitions/core.c:142 [inline]
 blk_add_partitions block/partitions/core.c:590 [inline]
 bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694
 blkdev_get_whole+0x187/0x290 block/bdev.c:764
 bdev_open+0x2c7/0xe40 block/bdev.c:973
 blkdev_open+0x34e/0x4f0 block/fops.c:697
 do_dentry_open+0x6d8/0x1660 fs/open.c:949
 vfs_open+0x82/0x3f0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2cfaaa7407
RSP: 002b:00007ffd77793060 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f2cfb259880 RCX: 00007f2cfaaa7407
RDX: 00000000000a0800 RSI: 0000558305f21f80 RDI: ffffffffffffff9c
RBP: 0000558305ce12c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055830604c100
R13: 0000558305f1c8d0 R14: 0000000000000000 R15: 000055830604c100
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by getty/5564:
 #0: ffff8880385fb0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
3 locks held by udevd/5835:
 #0: ffff88802788c358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:961
 #1: ffff888027348918 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff888027348918 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff888027348918 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x22e/0x670 block/blk-mq.c:2386
 #2: ffff8880279b8180 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
3 locks held by udevd/5836:
 #0: ffff888027ac6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:961
 #1: ffff88802644e918 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff88802644e918 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff88802644e918 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x22e/0x670 block/blk-mq.c:2386
 #2: ffff888027b20180 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
3 locks held by udevd/6567:
 #0: ffff888027970358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:961
 #1: ffff888027348398 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff888027348398 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff888027348398 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x22e/0x670 block/blk-mq.c:2386
 #2: ffff888027a00180 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
3 locks held by udevd/6600:
 #0: ffff888026cf6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:961
 #1: ffff88802644e218 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff88802644e218 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff88802644e218 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x22e/0x670 block/blk-mq.c:2386
 #2: ffff888027be0180 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
3 locks held by udevd/6739:
 #0: ffff888026cf2358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:961
 #1: ffff88802644e598 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff88802644e598 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff88802644e598 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x22e/0x670 block/blk-mq.c:2386
 #2: ffff888027bc8180 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
3 locks held by udevd/7098:
 #0: ffff888027974358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:961
 #1: ffff88802793b998 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff88802793b998 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff88802793b998 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x22e/0x670 block/blk-mq.c:2386
 #2: ffff888027ae8180 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
3 locks held by syz.4.8176/22898:
2 locks held by syz-executor/22899:

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xd25/0x1050 kernel/hung_task.c:515
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6141 Comm: kworker/0:5 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: events delayed_vfree_work
RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:63
Code: c6 20 17 1b 8c 48 c7 c7 60 17 1b 8c e9 f9 fe ff ff 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 89 fe 48 c7 c7 a0 17 1b 8c e9 cd fe ff ff 66 2e 0f
RSP: 0018:ffffc90003187948 EFLAGS: 00000046
RAX: ffff88807e108000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8b93ceda RDI: ffffffff8df6b20b
RBP: ffffffff9b45df18 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff90d9c017 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88812433c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2f7fbe7158 CR3: 0000000032070000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lockdep_recursion_inc kernel/locking/lockdep.c:465 [inline]
 lock_acquire kernel/locking/lockdep.c:5867 [inline]
 lock_acquire+0x18c/0x380 kernel/locking/lockdep.c:5825
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
 _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
 __debug_check_no_obj_freed lib/debugobjects.c:1105 [inline]
 debug_check_no_obj_freed+0x1c9/0x630 lib/debugobjects.c:1146
 __free_pages_prepare mm/page_alloc.c:1440 [inline]
 __free_frozen_pages+0x392/0x10d0 mm/page_alloc.c:2978
 vfree.part.0+0x12b/0x9d0 mm/vmalloc.c:3479
 vfree mm/vmalloc.c:3456 [inline]
 delayed_vfree_work+0x8e/0xd0 mm/vmalloc.c:3398
 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276
 process_scheduled_works kernel/workqueue.c:3359 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (823):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/28 13:07 upstream 7df48e363130 356bdfc9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nbd_queue_rq
2025/02/16 07:28 net 071ed42cff4f 40a34ec9 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2026/03/24 11:38 net-next ad6b67ffd2e8 baf8bf12 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2024/09/17 10:03 net-next 9410645520e9 c673ca06 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/04/18 05:46 upstream 8541d8f725c6 5be7a9de .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in nbd_queue_rq
2026/02/22 13:57 upstream 32a92f8c8932 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in nbd_queue_rq
2026/06/08 20:46 net 9772589b57e4 656e94c6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/30 18:37 net 78ef59e7a645 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/28 10:23 net 8ba68464e478 4c36e7e5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/23 21:44 net 87a1e0fe7776 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/23 19:13 net 87a1e0fe7776 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/18 08:48 net aaec7096f996 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2024/08/26 19:59 net 4186c8d9e6af 9aee4e0b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2024/08/23 23:02 net 8af174ea863c d7d32352 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2024/08/07 17:18 net 1ca645a2f74a 7b2f2f35 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in nbd_queue_rq
2026/06/07 00:00 net-next 903db046d557 cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/06/04 15:17 net-next c1c3d01e3a90 197909be .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/06/04 04:48 net-next a87533a80831 197909be .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/06/02 20:02 net-next 51e4eca2d360 62fe1528 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/06/01 07:33 net-next 841559836550 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/06/01 06:20 net-next 841559836550 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/06/01 03:38 net-next 841559836550 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/30 13:54 net-next 841559836550 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/30 06:02 net-next 841559836550 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/30 03:41 net-next 841559836550 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/30 02:37 net-next 841559836550 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/29 23:32 net-next 841559836550 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/29 05:00 net-next 9a82e387e27a 4624854e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/28 11:37 net-next 0cf905cb9a12 9a5a7e5e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/28 03:33 net-next 56ed77ff6022 4c36e7e5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/26 15:47 net-next 3baa7ba4ab98 a3e47276 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/25 15:00 net-next c0aa5f13826d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/22 03:12 net-next 1a1f055318d8 e195359d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/21 23:20 net-next 33fb2e2bc7a4 e195359d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/21 09:21 net-next 0ae361f7e43c 41b8c833 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/18 19:40 net-next 627ac78f2741 55156e84 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/18 13:18 net-next 627ac78f2741 55156e84 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/17 21:48 net-next 627ac78f2741 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/17 07:57 net-next 627ac78f2741 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/16 23:58 net-next 627ac78f2741 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/16 17:24 net-next 627ac78f2741 a15a64a6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/16 01:33 net-next 55834f0d7421 81fb92f3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/15 22:15 net-next 822d4a8e390a 81fb92f3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/15 20:13 net-next 822d4a8e390a 9cd3beaa .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/15 13:39 net-next 822d4a8e390a 9cd3beaa .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/15 09:00 net-next 822d4a8e390a 9cd3beaa .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/15 05:14 net-next 822d4a8e390a 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/15 01:17 net-next f3f7760afe65 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/14 20:20 net-next f3f7760afe65 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/14 16:02 net-next f3f7760afe65 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/14 12:21 net-next 1f8fd0fe5641 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/14 01:04 net-next 8ebd24a7822c 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/13 22:21 net-next 8ebd24a7822c 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/05/13 06:56 net-next 543bdc1578cd a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nbd_queue_rq
2026/01/05 12:53 linux-next f8f97927abf7 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in nbd_queue_rq
2024/12/27 05:11 linux-next 8155b4ef3466 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in nbd_queue_rq
2025/02/21 08:56 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci e6747d19291c 0808a665 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in nbd_queue_rq
* Struck through repros no longer work on HEAD.