INFO: rcu detected stall in sys_recvmmsg

Status: auto-obsoleted due to no activity on 2026/06/11 04:39
Reported-by: syzbot+426bd78d8547d0759eee@syzkaller.appspotmail.com
First crash: 386d, last: 158d
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_recvmmsg (3) prio:low net 1 286 5d13h 963d 0/29 upstream: reported on 2023/12/19 09:31
linux-6.1 INFO: rcu detected stall in sys_recvmmsg (3) 1 16 225d 620d 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 syz, C error 1 1324d 1324d 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 syz, C done 82 10d 1220d 0/3 upstream: reported C repro on 2023/04/06 01:32
linux-6.1 INFO: rcu detected stall in sys_recvmmsg (4) 1 3 13d 107d 0/3 upstream: reported on 2026/04/22 14:30
linux-6.1 INFO: rcu detected stall in sys_recvmmsg (2) 1 5 724d 855d 0/3 auto-obsoleted due to no activity on 2024/11/22 11:58
upstream INFO: rcu detected stall in sys_recvmmsg mptcp 1 syz, C done 52 1650d 1781d 20/29 fixed on 2022/03/08 16:11
linux-6.6 INFO: rcu detected stall in sys_recvmmsg (2) 1 3 9d14h 34d 0/2 upstream: reported on 2026/07/04 16:20
linux-6.1 INFO: rcu detected stall in sys_recvmmsg 1 5 1101d 1232d 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 1410d 1441d 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 744d 836d 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: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P33/1:b..l P20774/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=126261, q=32 ncpus=2)
task:syz.1.4875      state:R  running task     stack:25928 pid:20774 ppid:5770   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__sanitizer_cov_trace_pc+0x4f/0x60 kernel/kcov.c:222
Code: 75 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 83 fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc 15 00 00 <48> 39 cf 73 08 48 89 3a 48 89 44 f2 08 c3 0f 1f 00 f3 0f 1e fa 48
RSP: 0018:ffffc90003717650 EFLAGS: 00000246
RAX: ffffffff8a70db91 RBX: ffffc90003717720 RCX: 0000000000080000
RDX: ffffc9000e0ac000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff2237ea0
R10: dffffc0000000000 R11: fffffbfff2237ea1 R12: ffff88802695d000
R13: dffffc0000000000 R14: ffffc90003717738 R15: 1ffff920006e2eeb
 mas_start+0x371/0x470 lib/maple_tree.c:1393
 mas_state_walk lib/maple_tree.c:3707 [inline]
 mt_find+0x21a/0x650 lib/maple_tree.c:6548
 find_vma+0x134/0x1b0 mm/mmap.c:1888
 lock_mm_and_find_vma+0x5f/0x2f0 mm/memory.c:5443
 do_user_addr_fault+0x36c/0x12c0 arch/x86/mm/fault.c:1343
 handle_page_fault arch/x86/mm/fault.c:1463 [inline]
 exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:rep_movs_alternative+0x30/0x90 arch/x86/lib/copy_user_64.S:57
Code: f9 40 73 40 83 f9 08 73 21 85 c9 74 0f 8a 06 88 07 48 ff c7 48 ff c6 48 ff c9 75 f1 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 <48> 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08
RSP: 0018:ffffc90003717a50 EFLAGS: 00050206
RAX: ffffffff84297301 RBX: 0000000000000038 RCX: 0000000000000038
RDX: 0000000000000001 RSI: 00002000000bc000 RDI: ffffc90003717ae0
RBP: ffffc90003717c70 R08: ffffc90003717b17 R09: 1ffff920006e2f62
R10: dffffc0000000000 R11: fffff520006e2f63 R12: 00002000000bc038
R13: dffffc0000000000 R14: ffffc90003717ae0 R15: 00002000000bc000
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:127 [inline]
 _copy_from_user+0x8b/0xe0 lib/usercopy.c:23
 copy_from_user include/linux/uaccess.h:183 [inline]
 copy_msghdr_from_user net/socket.c:2524 [inline]
 recvmsg_copy_msghdr net/socket.c:2779 [inline]
 ___sys_recvmsg+0x176/0x590 net/socket.c:2851
 do_recvmmsg+0x39a/0x870 net/socket.c:2949
 __sys_recvmmsg net/socket.c:3028 [inline]
 __do_sys_recvmmsg net/socket.c:3051 [inline]
 __se_sys_recvmmsg net/socket.c:3044 [inline]
 __x64_sys_recvmmsg+0x199/0x250 net/socket.c:3044
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9dee39c799
RSP: 002b:00007f9def20f028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f9dee616090 RCX: 00007f9dee39c799
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f9dee432bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9dee616128 R14: 00007f9dee616090 R15: 00007ffd0238c9a8
 </TASK>
task:kworker/u4:2    state:R  running task     stack:21096 pid:33    ppid:2      flags:0x00004000
Workqueue: events_unbound bpf_map_free_deferred
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:692
RIP: 0010:lock_is_held_type+0x13e/0x190 kernel/locking/lockdep.c:5830
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc90000a9f918 EFLAGS: 00000206
RAX: a38f97698a3e7d00 RBX: ffff8880182e8000 RCX: a38f97698a3e7d00
RDX: 0000000000000000 RSI: ffffffff8acada80 RDI: ffffffff8b1c82e0
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff2237ea0
R10: dffffc0000000000 R11: fffffbfff2237ea1 R12: 0000000000000002
R13: 0000000000000246 R14: ffffffff8d131fa0 R15: ffff8880182e8b30
 lookup_page_ext mm/page_ext.c:240 [inline]
 page_ext_get+0x193/0x2b0 mm/page_ext.c:509
 __reset_page_owner+0x2e/0x190 mm/page_owner.c:145
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1181 [inline]
 free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2458
 vfree+0x1a6/0x320 mm/vmalloc.c:2868
 htab_map_free+0x81a/0xa50 kernel/bpf/hashtab.c:1579
 bpf_map_free_deferred+0xfc/0x120 kernel/bpf/syscall.c:703
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: rcu_preempt kthread starved for 10572 jiffies! g126261 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:R  running task     stack:26728 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: c7 22 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 83 d1 43 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2e 41 89 de 80
RSP: 0018:ffffc90000187de0 EFLAGS: 000002c2
RAX: ba76401d4119de00 RBX: ffffffff8162a490 RCX: ba76401d4119de00
RDX: 0000000000000001 RSI: ffffffff8acac900 RDI: ffffffff8b1c82e0
RBP: ffffc90000187f20 R08: ffff8880b8f36b2b R09: 1ffff110171e6d65
R10: dffffc0000000000 R11: ffffed10171e6d66 R12: 1ffff110036ce780
R13: 1ffff92000030fc8 R14: 0000000000000001 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8969772ff8 CR3: 000000003e98a000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000001800
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:170 [inline]
 do_idle+0x1f0/0x4e0 kernel/sched/idle.c:282
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/03 04:38 linux-6.6.y 7a137e9bfa0e 28b83e23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_recvmmsg
2026/01/17 07:07 linux-6.6.y c596736dadab 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_recvmmsg
2025/10/27 23:55 linux-6.6.y 4a243110dc88 fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_recvmmsg
2025/10/19 13:47 linux-6.6.y 0bbbd97a442d 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_recvmmsg
2025/10/17 17:57 linux-6.6.y 0bbbd97a442d 7adf5298 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_recvmmsg
2025/09/21 04:05 linux-6.6.y af1544b5d072 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_recvmmsg
2025/08/06 05:44 linux-6.6.y 3a8ababb8b6a ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_recvmmsg
2025/07/18 08:32 linux-6.6.y d96eb99e2f0e 88248e14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_recvmmsg
* Struck through repros no longer work on HEAD.