INFO: rcu detected stall in pipe_write (2)

Status: upstream: reported on 2026/06/18 20:17
Reported-by: syzbot+55e136f09f8f16894496@syzkaller.appspotmail.com
First crash: 116d, last: 2d09h
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in pipe_write 1 1 238d 238d 0/3 auto-obsoleted due to no activity on 2026/05/27 17:40
upstream INFO: rcu detected stall in pipe_write (2) cgroups mm 1 1 2470d 2470d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in pipe_write mm 1 1 2506d 2506d 0/29 closed as invalid on 2019/12/04 14:04
linux-6.1 INFO: rcu detected stall in pipe_write 1 1 849d 849d 0/3 auto-obsoleted due to no activity on 2024/09/24 01:17
upstream INFO: rcu detected stall in pipe_write (3) mm 1 2 852d 882d 0/29 auto-obsoleted due to no activity on 2024/09/11 11:25

Sample crash report:
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 ticks this GP) idle=149/1/0x4000000000000000 softirq=92035/92035 fqs=0 
	(detected by 1, t=10506 jiffies, g=134505, q=10576)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2835 Comm: syz.5.6134 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:perf_trace_lock+0x4/0x390 include/trace/events/lock.h:39
Code: 08 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 3e ff ff ff e8 90 cb 61 00 e9 34 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 55 48 89 e5 <41> 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec c0 00 00 00 49 89
RSP: 0018:ffffc90000007790 EFLAGS: 00000046
RAX: 1ffff11004194453 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: ffffffff81831185 RSI: ffffffff8d11efa0 RDI: ffffffff8cfee060
RBP: ffffc90000007790 R08: ffffffff8e6b282f R09: 1ffffffff1cd6505
R10: dffffc0000000000 R11: fffffbfff1cd6506 R12: 1ffff92000000f00
R13: dffffc0000000000 R14: ffff888020ca2298 R15: 1ffff92000000f00
FS:  00007fba208cb6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000156000 CR3: 000000005fc59000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000200000000bc0 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 trace_lock_release include/trace/events/lock.h:58 [inline]
 lock_release+0x84a/0x8a0 kernel/locking/lockdep.c:5748
 rcu_read_unlock include/linux/rcupdate.h:773 [inline]
 BPF_PROG_RUN_ARRAY include/linux/bpf.h:1446 [inline]
 trace_call_bpf+0x4fe/0x5b0 kernel/trace/bpf_trace.c:127
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10026
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:__rcu_read_unlock+0x73/0xd0 kernel/rcu/tree_plugin.h:422
Code: 84 c0 75 5f 41 83 3e 00 75 20 43 0f b6 04 3c 84 c0 75 3a 8b 03 3d 00 00 00 40 73 0a 5b 41 5c 41 5d 41 5e 41 5f c3 0f 0b eb f2 <e8> 58 00 00 00 eb d9 89 d9 80 e1 07 80 c1 03 38 c1 7c ac 49 89 fe
RSP: 0018:ffffc90000007be8 EFLAGS: 00000206
RAX: 0000000000000000 RBX: ffff888046e7bfbc RCX: ffff888046e7bb80
RDX: 0000000000000100 RSI: ffffffff8a7a4be0 RDI: ffff888046e7bb80
RBP: 0000000000000002 R08: ffffffff8e6b282f R09: 1ffffffff1cd6505
R10: dffffc0000000000 R11: fffffbfff1cd6506 R12: 1ffff11008dcf7f7
R13: 0000000000019000 R14: ffff888046e7bfc0 R15: dffffc0000000000
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 ieee80211_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831
 mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4ea/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 5f ce 86 f7 65 8b 05 e0 e4 36 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000328f9e0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 9bcb42d6519c2300
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001
RBP: ffffc9000328fa70 R08: ffff8880b8e3b30b R09: 1ffff110171c7661
R10: dffffc0000000000 R11: ffffed10171c7662 R12: dffffc0000000000
R13: 0000000000000a06 R14: ffff88806200c4e0 R15: 1ffff92000651f3c
 spin_unlock_irqrestore include/linux/spinlock.h:419 [inline]
 prepare_to_wait_event+0x42c/0x460 kernel/sched/wait.c:332
 pipe_write+0xcd5/0x1b40 fs/pipe.c:575
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fba226941d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fba208cb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fba2291c090 RCX: 00007fba226941d9
RDX: 00000000fffffdef RSI: 0000200000003a80 RDI: 0000000000000000
RBP: 00007fba2272b888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fba2291c128 R14: 00007fba2291c090 R15: 00007ffde4e29ea8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10505 jiffies! g134505 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=112138
rcu: rcu_preempt kthread starved for 10506 jiffies! g134505 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:26864 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2835 Comm: syz.5.6134 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:trace_lock_release include/trace/events/lock.h:58 [inline]
RIP: 0010:lock_release+0xae/0x8a0 kernel/locking/lockdep.c:5748
Code: 83 fb 08 0f 83 4e 05 00 00 89 d8 c1 e8 06 48 8d 3c c5 28 28 6b 8e be 08 00 00 00 e8 6c f8 60 00 89 d8 48 0f a3 05 9a b6 0d 0d <73> 0d e8 2b 52 07 00 84 c0 0f 84 53 05 00 00 48 c7 c0 c4 5b 6b 8e
RSP: 0018:ffffc900000077a0 EFLAGS: 00000057
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff815d7184
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e6b2828
RBP: ffffc900000078b0 R08: ffffffff8e6b282f R09: 1ffffffff1cd6505
R10: dffffc0000000000 R11: fffffbfff1cd6506 R12: 1ffff92000000f00
R13: dffffc0000000000 R14: ffff888020ca2298 R15: 1ffff92000000f00
FS:  00007fba208cb6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000156000 CR3: 000000005fc59000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000200000000bc0 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 rcu_read_unlock include/linux/rcupdate.h:773 [inline]
 BPF_PROG_RUN_ARRAY include/linux/bpf.h:1446 [inline]
 trace_call_bpf+0x4fe/0x5b0 kernel/trace/bpf_trace.c:127
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10026
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:__rcu_read_unlock+0x73/0xd0 kernel/rcu/tree_plugin.h:422
Code: 84 c0 75 5f 41 83 3e 00 75 20 43 0f b6 04 3c 84 c0 75 3a 8b 03 3d 00 00 00 40 73 0a 5b 41 5c 41 5d 41 5e 41 5f c3 0f 0b eb f2 <e8> 58 00 00 00 eb d9 89 d9 80 e1 07 80 c1 03 38 c1 7c ac 49 89 fe
RSP: 0018:ffffc90000007be8 EFLAGS: 00000206
RAX: 0000000000000000 RBX: ffff888046e7bfbc RCX: ffff888046e7bb80
RDX: 0000000000000100 RSI: ffffffff8a7a4be0 RDI: ffff888046e7bb80
RBP: 0000000000000002 R08: ffffffff8e6b282f R09: 1ffffffff1cd6505
R10: dffffc0000000000 R11: fffffbfff1cd6506 R12: 1ffff11008dcf7f7
R13: 0000000000019000 R14: ffff888046e7bfc0 R15: dffffc0000000000
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 ieee80211_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831
 mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4ea/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 5f ce 86 f7 65 8b 05 e0 e4 36 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000328f9e0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 9bcb42d6519c2300
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001
RBP: ffffc9000328fa70 R08: ffff8880b8e3b30b R09: 1ffff110171c7661
R10: dffffc0000000000 R11: ffffed10171c7662 R12: dffffc0000000000
R13: 0000000000000a06 R14: ffff88806200c4e0 R15: 1ffff92000651f3c
 spin_unlock_irqrestore include/linux/spinlock.h:419 [inline]
 prepare_to_wait_event+0x42c/0x460 kernel/sched/wait.c:332
 pipe_write+0xcd5/0x1b40 fs/pipe.c:575
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fba226941d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fba208cb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fba2291c090 RCX: 00007fba226941d9
RDX: 00000000fffffdef RSI: 0000200000003a80 RDI: 0000000000000000
RBP: 00007fba2272b888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fba2291c128 R14: 00007fba2291c090 R15: 00007ffde4e29ea8
 </TASK>
net_ratelimit: 10694 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
net_ratelimit: 8732 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/11 05:12 linux-5.15.y a051a4bf909f 4f92358f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in pipe_write
2026/09/20 14:00 linux-5.15.y 0248c33e835e 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in pipe_write
2026/06/18 20:16 linux-5.15.y dc027a595035 a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in pipe_write
* Struck through repros no longer work on HEAD.