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INFO: rcu detected stall in sys_recvmmsg (4)

Status: upstream: reported on 2026/04/22 14:30
Reported-by: syzbot+b089ec3c3cd5d4bbd763@syzkaller.appspotmail.com
First crash: 11d, last: 11d
▶ ▼ Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_recvmmsg (3) mm 1 246 22h28m 867d 0/29 upstream: reported on 2023/12/19 09:31
linux-6.1 INFO: rcu detected stall in sys_recvmmsg (3) 1 16 129d 524d 0/3 auto-obsoleted due to no activity on 2026/04/05 10:37
linux-4.19 INFO: rcu detected stall in sys_recvmmsg 1 C error 1 1228d 1228d 0/1 upstream: reported C repro on 2022/12/23 04:58
linux-5.15 INFO: rcu detected stall in sys_recvmmsg missing-backport origin:upstream 1 C done 67 10d 1124d 0/3 upstream: reported C repro on 2023/04/06 01:32
linux-6.6 INFO: rcu detected stall in sys_recvmmsg 1 8 62d 290d 0/2 upstream: reported on 2025/07/18 08:32
linux-6.1 INFO: rcu detected stall in sys_recvmmsg (2) 1 5 628d 759d 0/3 auto-obsoleted due to no activity on 2024/11/22 11:58
upstream INFO: rcu detected stall in sys_recvmmsg mptcp 1 C done 52 1554d 1685d 20/29 fixed on 2022/03/08 16:11
linux-6.1 INFO: rcu detected stall in sys_recvmmsg 1 5 1005d 1136d 0/3 auto-obsoleted due to no activity on 2023/11/11 06:06
upstream INFO: rcu detected stall in sys_recvmmsg (2) net 1 4 1314d 1345d 0/29 auto-obsoleted due to no activity on 2023/01/03 09:53
android-5-15 BUG: soft lockup in sys_recvmmsg 1 5 648d 740d 0/2 auto-obsoleted due to no activity on 2024/10/23 09:30

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (28 ticks this GP) idle=ec54/1/0x4000000000000000 softirq=43384/43384 fqs=0
	(detected by 1, t=10502 jiffies, g=60973, q=429 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 12245 Comm: syz.1.1399 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:87 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x8a/0x290 mm/kasan/generic.c:189
Code: 1c 21 49 89 df 4d 29 df 49 83 ff 10 7f 29 4d 85 ff 0f 84 38 01 00 00 4c 89 cb 48 f7 d3 4c 01 f3 41 80 3b 00 0f 85 86 01 00 00 <49> ff c3 48 ff c3 75 ee e9 18 01 00 00 44 89 dd 83 e5 07 0f 84 b5
RSP: 0018:ffffc90000007c70 EFLAGS: 00000046
RAX: 000000000000a001 RBX: ffffffffffffffff RCX: ffffffff88637f7b
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff888056779620
RBP: ffff8880566ce340 R08: ffff888056779623 R09: 1ffff1100acef2c4
R10: dffffc0000000000 R11: ffffed100acef2c4 R12: dffffc0000000001
R13: 0000000001f403e8 R14: 1ffff1100acef2c4 R15: 0000000000000001
FS:  00007fa3da6936c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa3da692ff8 CR3: 0000000027092000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 instrument_atomic_write include/linux/instrumented.h:87 [inline]
 atomic_set include/linux/atomic/atomic-instrumented.h:41 [inline]
 taprio_set_budget net/sched/sch_taprio.c:549 [inline]
 advance_sched+0x63b/0x970 net/sched/sch_taprio.c:745
 __run_hrtimer kernel/time/hrtimer.c:1747 [inline]
 __hrtimer_run_queues+0x54a/0xd50 kernel/time/hrtimer.c:1811
 hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [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> 2f dd 20 f7 65 8b 05 80 60 ca 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900048975a0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: fcefb3f355013600
RDX: dffffc0000000000 RSI: ffffffff8a8c1120 RDI: 0000000000000001
RBP: ffffc90004897630 R08: ffffffff90af92ef R09: 1ffffffff215f25d
R10: dffffc0000000000 R11: fffffbfff215f25e R12: dffffc0000000000
R13: 0000000000000000 R14: ffff88802e612ec0 R15: 1ffff92000912eb4
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x128/0x190 kernel/sched/wait.c:208
 __unix_dgram_recvmsg+0x4c3/0xdc0 net/unix/af_unix.c:2478
 ____sys_recvmsg+0x2cb/0x5e0 net/socket.c:-1
 ___sys_recvmsg+0x212/0x590 net/socket.c:2779
 do_recvmmsg+0x393/0x870 net/socket.c:2873
 __sys_recvmmsg net/socket.c:2952 [inline]
 __do_sys_recvmmsg net/socket.c:2975 [inline]
 __se_sys_recvmmsg net/socket.c:2968 [inline]
 __x64_sys_recvmmsg+0x195/0x250 net/socket.c:2968
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa3d979c819
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:00007fa3da693028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007fa3d9a16090 RCX: 00007fa3d979c819
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007fa3d9832c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa3d9a16128 R14: 00007fa3d9a16090 R15: 00007ffcf6b197a8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g60973 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=47178
rcu: rcu_preempt kthread starved for 10502 jiffies! g60973 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:26416 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </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: 12245 Comm: syz.1.1399 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:212
Code: 2e 0f 1f 84 00 00 00 00 00 90 53 48 89 fb e8 17 00 00 00 48 8b 3d 10 81 9d 0c 48 89 de 5b e9 b7 42 50 00 00 00 cc cc 00 00 cc <48> 8b 04 24 65 48 8b 0d e4 f9 7f 7e 65 8b 15 e5 f9 7f 7e 81 e2 00
RSP: 0018:ffffc90000007c98 EFLAGS: 00000086
RAX: 0000000000000000 RBX: ffff888026d16800 RCX: 1ffff1100b2da667
RDX: 0000000000010000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffff8880596d3340 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000f84 R12: ffff8880596d32e8
R13: dffffc0000000000 R14: ffff8880596d3000 R15: ffff888026e73c80
FS:  00007fa3da6936c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa3da692ff8 CR3: 0000000027092000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 advance_sched+0x1ac/0x970 net/sched/sch_taprio.c:708
 __run_hrtimer kernel/time/hrtimer.c:1747 [inline]
 __hrtimer_run_queues+0x54a/0xd50 kernel/time/hrtimer.c:1811
 hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [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> 2f dd 20 f7 65 8b 05 80 60 ca 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900048975a0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: fcefb3f355013600
RDX: dffffc0000000000 RSI: ffffffff8a8c1120 RDI: 0000000000000001
RBP: ffffc90004897630 R08: ffffffff90af92ef R09: 1ffffffff215f25d
R10: dffffc0000000000 R11: fffffbfff215f25e R12: dffffc0000000000
R13: 0000000000000000 R14: ffff88802e612ec0 R15: 1ffff92000912eb4
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x128/0x190 kernel/sched/wait.c:208
 __unix_dgram_recvmsg+0x4c3/0xdc0 net/unix/af_unix.c:2478
 ____sys_recvmsg+0x2cb/0x5e0 net/socket.c:-1
 ___sys_recvmsg+0x212/0x590 net/socket.c:2779
 do_recvmmsg+0x393/0x870 net/socket.c:2873
 __sys_recvmmsg net/socket.c:2952 [inline]
 __do_sys_recvmmsg net/socket.c:2975 [inline]
 __se_sys_recvmmsg net/socket.c:2968 [inline]
 __x64_sys_recvmmsg+0x195/0x250 net/socket.c:2968
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa3d979c819
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:00007fa3da693028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007fa3d9a16090 RCX: 00007fa3d979c819
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007fa3d9832c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa3d9a16128 R14: 00007fa3d9a16090 R15: 00007ffcf6b197a8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/22 14:29 linux-6.1.y 7c87defbd336 4595e353 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_recvmmsg
* Struck through repros no longer work on HEAD.