BUG: soft lockup in kernfs_fop_write_iter

Status: auto-obsoleted due to no activity on 2025/08/11 05:47
Reported-by: syzbot+ff612915df3949aba476@syzkaller.appspotmail.com
First crash: 459d, last: 459d
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in kernfs_fop_write_iter (3) prio:low net 1 syz error error 24 35d 219d 0/29 upstream: reported syz repro on 2026/01/07 17:45
upstream INFO: rcu detected stall in kernfs_fop_write_iter (2) net mm 1 4 478d 638d 0/29 auto-obsoleted due to no activity on 2025/07/23 14:56
linux-6.1 INFO: rcu detected stall in kernfs_fop_write_iter (4) 1 2 159d 226d 0/3 auto-obsoleted due to no activity on 2026/06/17 16:43
linux-5.15 INFO: rcu detected stall in kernfs_fop_write_iter 1 1 656d 656d 0/3 auto-obsoleted due to no activity on 2025/02/05 10:26
linux-6.1 INFO: rcu detected stall in kernfs_fop_write_iter (2) 1 2 739d 836d 0/3 auto-obsoleted due to no activity on 2024/11/14 04:13
linux-6.1 INFO: rcu detected stall in kernfs_fop_write_iter (3) 1 1 339d 339d 0/3 auto-obsoleted due to no activity on 2025/12/19 09:23
linux-5.15 INFO: rcu detected stall in kernfs_fop_write_iter (2) 1 2 4d04h 103d 0/3 upstream: reported on 2026/05/04 00:10
upstream INFO: rcu detected stall in kernfs_fop_write_iter fs sctp 1 7 732d 828d 0/29 auto-obsoleted due to no activity on 2024/11/10 20:48
linux-6.1 INFO: rcu detected stall in kernfs_fop_write_iter 1 1 1115d 1115d 0/3 auto-obsoleted due to no activity on 2023/11/03 22:13

Sample crash report:
RBP: 00007fe0b0e10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe0b0fb5fa0 R15: 00007fff66c1d808
 </TASK>
watchdog: BUG: soft lockup - CPU#0 stuck for 225s! [syz.0.637:2761]
Modules linked in:
CPU: 0 PID: 2761 Comm: syz.0.637 Not tainted 6.1.134-syzkaller-00012-g646380b087a5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:434 [inline]
RIP: 0010:__pv_queued_spin_lock_slowpath+0x591/0xc40 kernel/locking/qspinlock.c:511
Code: 0f 85 33 01 00 00 41 c6 45 00 00 41 0f b6 04 17 84 c0 0f 85 46 01 00 00 48 8b 44 24 10 c6 00 01 41 bd 00 80 ff ff eb 07 f3 90 <41> ff c5 74 5b 41 0f b6 04 16 84 c0 75 35 80 3b 00 75 eb 48 89 df
RSP: 0018:ffffc90000e47600 EFLAGS: 00000206
RAX: 0000000000000000 RBX: ffffffff86fd0ea8 RCX: ffffffff84efb682
RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffffffff86fd0ea8
RBP: ffffc90000e476f0 R08: dffffc0000000000 R09: fffffbfff0dfa1d6
R10: fffffbfff0dfa1d6 R11: 1ffffffff0dfa1d5 R12: 1ffff1103ee00001
R13: 00000000ffff9482 R14: 1ffffffff0dfa1d5 R15: 1ffffffff0dfa1d5
FS:  00007fe0b1bcb6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000112844000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock include/linux/spinlock.h:187 [inline]
 __raw_spin_lock include/linux/spinlock_api_smp.h:134 [inline]
 _raw_spin_lock+0xd8/0xe0 kernel/locking/spinlock.c:154
 __mutex_lock_common kernel/locking/mutex.c:641 [inline]
 __mutex_lock+0x3db/0x16d0 kernel/locking/mutex.c:775
 __mutex_lock_slowpath+0xe/0x10 kernel/locking/mutex.c:1064
 mutex_lock+0xf8/0x1a0 kernel/locking/mutex.c:296
 cgroup_lock include/linux/cgroup.h:445 [inline]
 cgroup_kn_lock_live+0x165/0x2e0 kernel/cgroup/cgroup.c:1672
 __cgroup_procs_write+0x75/0x2d0 kernel/cgroup/cgroup.c:5197
 cgroup_procs_write+0x27/0x50 kernel/cgroup/cgroup.c:5237
 cgroup_file_write+0x2a7/0x580 kernel/cgroup/cgroup.c:4119
 kernfs_fop_write_iter+0x2d6/0x410 fs/kernfs/file.c:334
 call_write_iter include/linux/fs.h:2274 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x5db/0xca0 fs/read_write.c:584
 ksys_write+0x140/0x240 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:646
 x64_sys_call+0x27b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe0b0d8e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe0b1bcb038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fe0b0fb5fa0 RCX: 00007fe0b0d8e969
RDX: 0000000000000012 RSI: 00002000000005c0 RDI: 0000000000000009
RBP: 00007fe0b0e10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe0b0fb5fa0 R15: 00007fff66c1d808
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 2698 Comm: syz-executor Not tainted 6.1.134-syzkaller-00012-g646380b087a5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
RIP: 0010:native_halt arch/x86/include/asm/irqflags.h:57 [inline]
RIP: 0010:halt arch/x86/include/asm/irqflags.h:98 [inline]
RIP: 0010:kvm_wait+0xcc/0x140 arch/x86/kernel/kvm.c:1058
Code: 20 f6 44 24 21 02 75 24 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 48 0f b6 07 40 38 f0 75 a6 66 90 0f 00 2d 15 b7 13 04 f4 <eb> 9a fa 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 3f 0f b6 07
RSP: 0018:ffffc90000df6ee0 EFLAGS: 00000046
RAX: 0000000000000003 RBX: ffff888110780140 RCX: ffffffff84efb682
RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffff888110780140
RBP: ffffc90000df6f70 R08: dffffc0000000000 R09: ffffed10220f0029
R10: ffffed10220f0029 R11: 1ffff110220f0028 R12: 1ffff1103ee20001
R13: ffff8881f7138bf4 R14: dffffc0000000000 R15: 1ffff920001beddc
FS:  0000555594e7f500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000135b24000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 pv_wait arch/x86/include/asm/paravirt.h:603 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x690/0xc40 kernel/locking/qspinlock.c:511
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock include/linux/spinlock.h:187 [inline]
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0x108/0x110 kernel/locking/spinlock.c:162
 __queue_map_get+0xe4/0x3d0 kernel/bpf/queue_stack_maps.c:109
 queue_map_peek_elem+0x1f/0x30 kernel/bpf/queue_stack_maps.c:171
 bpf_prog_00798911c748094f+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:987 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2282 [inline]
 bpf_trace_run2+0xff/0x250 kernel/trace/bpf_trace.c:2321
 __bpf_trace_contention_end+0xb/0x10 include/trace/events/lock.h:122
 __traceiter_contention_end+0x8c/0xc0 include/trace/events/lock.h:122
 trace_contention_end include/trace/events/lock.h:122 [inline]
 __pv_queued_spin_lock_slowpath+0xbff/0xc40 kernel/locking/qspinlock.c:560
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock include/linux/spinlock.h:187 [inline]
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0x108/0x110 kernel/locking/spinlock.c:162
 __queue_map_get+0xe4/0x3d0 kernel/bpf/queue_stack_maps.c:109
 queue_map_peek_elem+0x1f/0x30 kernel/bpf/queue_stack_maps.c:171
 bpf_prog_00798911c748094f+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:987 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2282 [inline]
 bpf_trace_run2+0xff/0x250 kernel/trace/bpf_trace.c:2321
 __bpf_trace_contention_end+0xb/0x10 include/trace/events/lock.h:122
 __traceiter_contention_end+0x8c/0xc0 include/trace/events/lock.h:122
 trace_contention_end include/trace/events/lock.h:122 [inline]
 __mutex_lock_common kernel/locking/mutex.c:748 [inline]
 __mutex_lock+0xd22/0x16d0 kernel/locking/mutex.c:775
 __mutex_lock_slowpath+0xe/0x10 kernel/locking/mutex.c:1064
 mutex_lock+0xf8/0x1a0 kernel/locking/mutex.c:296
 cgroup_lock include/linux/cgroup.h:445 [inline]
 cgroup_kn_lock_live+0x165/0x2e0 kernel/cgroup/cgroup.c:1672
 __cgroup_procs_write+0x75/0x2d0 kernel/cgroup/cgroup.c:5197
 cgroup_procs_write+0x27/0x50 kernel/cgroup/cgroup.c:5237
 cgroup_file_write+0x2a7/0x580 kernel/cgroup/cgroup.c:4119
 kernfs_fop_write_iter+0x2d6/0x410 fs/kernfs/file.c:334
 call_write_iter include/linux/fs.h:2274 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x5db/0xca0 fs/read_write.c:584
 ksys_write+0x140/0x240 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:646
 x64_sys_call+0x27b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff43eb8d3e0
Code: 40 00 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 80 3d 61 71 1f 00 00 74 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 48 83 ec 28 48 89
RSP: 002b:00007fffba1736c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007ff43eb8d3e0
RDX: 0000000000000001 RSI: 00007fffba1736f0 RDI: 0000000000000003
RBP: 00007fffba173c60 R08: 0000000000000001 R09: 00007fffba1734f7
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000001
R13: 00007fffba1736f0 R14: 00007fffba173c20 R15: 00007fffba173c60
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/13 05:42 android14-6.1 646380b087a5 f6671af7 .config console log report info ci2-android-6-1-perf BUG: soft lockup in kernfs_fop_write_iter
* Struck through repros no longer work on HEAD.