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INFO: rcu detected stall in sys_exit_group (4)

Status: upstream: reported C repro on 2025/09/19 02:54
Reported-by: syzbot+6584e37abad5c8d5ecf4@syzkaller.appspotmail.com
First crash: 2h56m, last: 2h56m
▶ ▼ Similar bugs (16)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_exit_group (7) net 1 C unreliable inconclusive 90 437d 1434d 0/29 upstream: reported C repro on 2021/10/15 18:41
upstream INFO: rcu detected stall in sys_exit_group (6) mm 1 C 4 1814d 1820d 19/29 fixed on 2021/03/10 01:48
linux-5.15 INFO: rcu detected stall in sys_exit_group (2) 1 3 519d 553d 0/3 auto-obsoleted due to no activity on 2024/07/27 04:53
linux-6.1 INFO: rcu detected stall in sys_exit_group (3) origin:upstream 1 C error 17 40d 604d 0/3 upstream: reported C repro on 2024/01/23 11:05
linux-6.1 INFO: rcu detected stall in sys_exit_group (2) 1 1 751d 751d 0/3 auto-obsoleted due to no activity on 2023/12/07 20:57
linux-6.1 INFO: rcu detected stall in sys_exit_group 1 1 862d 862d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:06
linux-5.15 INFO: rcu detected stall in sys_exit_group 1 1 813d 813d 0/3 auto-obsoleted due to no activity on 2023/10/06 21:30
upstream INFO: rcu detected stall in sys_exit_group (2) mm cgroups 1 56 2115d 2117d 0/29 closed as invalid on 2019/12/04 14:14
linux-6.6 INFO: rcu detected stall in sys_exit_group 1 4 2d03h 59d 0/2 upstream: reported on 2025/07/21 16:02
upstream INFO: rcu detected stall in sys_exit_group (3) mm 1 8 2081d 2081d 0/29 closed as invalid on 2020/01/08 05:23
upstream INFO: rcu detected stall in sys_exit_group (4) mm 1 13 2080d 2081d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in sys_exit_group (5) mm 1 1 2001d 2001d 0/29 auto-closed as invalid on 2020/06/25 07:58
linux-5.15 INFO: rcu detected stall in sys_exit_group (3) 1 2 308d 341d 0/3 auto-obsoleted due to no activity on 2025/02/22 19:05
upstream INFO: rcu detected stall in sys_exit_group kernel 1 C done 1 2196d 2192d 13/29 fixed on 2019/10/09 10:54
android-5-10 BUG: soft lockup in sys_exit_group 1 1 424d 424d 0/2 auto-obsoleted due to no activity on 2024/10/19 10:22
android-5-15 BUG: soft lockup in sys_exit_group 1 C error 7 386d 529d 0/2 auto-obsoleted due to no activity on 2024/12/07 01:30

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 ticks this GP) idle=967/1/0x4000000000000000 softirq=6640/6640 fqs=0 
	(detected by 0, t=10502 jiffies, g=7357, q=527)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4320 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:check_wait_context kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__lock_acquire+0x6fb/0x7c60 kernel/locking/lockdep.c:4962
Code: 43 48 8d 04 9b 49 8d 5c c5 00 48 89 d8 48 c1 e8 03 42 0f b6 04 00 84 c0 75 45 8b 1b 48 8b 44 24 58 42 0f b6 04 00 84 c0 75 55 <48> 8b 44 24 18 33 18 41 ff ce 49 ff cf f7 c3 00 60 00 00 74 a8 e9
RSP: 0018:ffffc90000dd0860 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 00000000000c4060 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8ffbc0c0
RBP: ffffc90000dd0ab0 R08: dffffc0000000000 R09: fffffbfff1ff7819
R10: fffffbfff1ff7819 R11: 1ffffffff1ff7818 R12: 0000000000000000
R13: ffff8880229be450 R14: 0000000000000003 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555562a33808 CR3: 000000007343f000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
 debug_object_activate+0x65/0x480 lib/debugobjects.c:694
 debug_hrtimer_activate kernel/time/hrtimer.c:410 [inline]
 debug_activate kernel/time/hrtimer.c:465 [inline]
 enqueue_hrtimer+0x30/0x370 kernel/time/hrtimer.c:1074
 __run_hrtimer kernel/time/hrtimer.c:1707 [inline]
 __hrtimer_run_queues+0x65a/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/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:should_resched arch/x86/include/asm/preempt.h:-1 [inline]
RIP: 0010:unwind_next_frame+0x129d/0x1d90 arch/x86/kernel/unwind_orc.c:616
Code: 0f 85 a0 02 00 00 c6 05 ef 60 21 0c 01 48 c7 c7 e0 81 08 8a e9 3d fa ff ff bf 01 00 00 00 e8 ea e6 1c 00 65 8b 0d cb e4 cd 7e <b0> 01 85 c9 0f 85 d3 02 00 00 e8 74 ef cb ff e9 c9 02 00 00 80 3d
RSP: 0018:ffffc900031ff528 EFLAGS: 00000297
RAX: 0000000080000001 RBX: ffffc900031ff5e8 RCX: 0000000080000000
RDX: ffffc900031ff601 RSI: ffffc900031ff998 RDI: 00000000ffffffff
RBP: ffffc900031ff630 R08: dffffc0000000000 R09: ffffc900031ff638
R10: fffff5200063fec9 R11: 1ffff9200063fec7 R12: ffffc900031f8000
R13: dffffc0000000000 R14: ffffc900031ff5f8 R15: ffffc900031ff9a8
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 anon_vma_chain_free mm/rmap.c:143 [inline]
 unlink_anon_vmas+0x2c8/0x660 mm/rmap.c:417
 free_pgtables+0x74/0x2a0 mm/memory.c:412
 exit_mmap+0x39e/0x5f0 mm/mmap.c:3217
 __mmput+0x115/0x3b0 kernel/fork.c:1127
 exit_mm+0x567/0x6c0 kernel/exit.c:550
 do_exit+0x5a1/0x20a0 kernel/exit.c:870
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 __do_sys_exit_group kernel/exit.c:1008 [inline]
 __se_sys_exit_group kernel/exit.c:1006 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
 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: 0033:0x7f25dc622ba9
Code: Unable to access opcode bytes at RIP 0x7f25dc622b7f.
RSP: 002b:00007ffc7023a5a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f25dc622ba9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 000000057023a69f R09: 00007f25dc835280
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f25dc835280 R14: 0000000000000003 R15: 00007ffc7023a660
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g7357 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=2499
rcu: rcu_preempt kthread starved for 10502 jiffies! g7357 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27848 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4320 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__run_hrtimer kernel/time/hrtimer.c:1671 [inline]
RIP: 0010:__hrtimer_run_queues+0x427/0xc40 kernel/time/hrtimer.c:1754
Code: 84 c0 0f 85 cd 04 00 00 41 21 1e 48 8b 44 24 18 4c 8d 70 28 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 19 7b 54 00 <49> 8b 06 48 89 44 24 60 48 8b 7c 24 40 48 8b b4 24 b8 00 00 00 e8
RSP: 0018:ffffc90000dd0d20 EFLAGS: 00000046
RAX: 1ffff1100475c96d RBX: 00000000fffffffd RCX: 0000000000000001
RDX: 0000000000010000 RSI: 0000000000000001 RDI: 0000000000000020
RBP: ffffc90000dd0e98 R08: dffffc0000000000 R09: fffffbfff1ad323e
R10: fffffbfff1ad323e R11: 1ffffffff1ad323d R12: ffff8880b912a350
R13: 1ffff1101722546a R14: ffff888023ae4b68 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555562a33808 CR3: 000000007343f000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/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:should_resched arch/x86/include/asm/preempt.h:-1 [inline]
RIP: 0010:unwind_next_frame+0x129d/0x1d90 arch/x86/kernel/unwind_orc.c:616
Code: 0f 85 a0 02 00 00 c6 05 ef 60 21 0c 01 48 c7 c7 e0 81 08 8a e9 3d fa ff ff bf 01 00 00 00 e8 ea e6 1c 00 65 8b 0d cb e4 cd 7e <b0> 01 85 c9 0f 85 d3 02 00 00 e8 74 ef cb ff e9 c9 02 00 00 80 3d
RSP: 0018:ffffc900031ff528 EFLAGS: 00000297
RAX: 0000000080000001 RBX: ffffc900031ff5e8 RCX: 0000000080000000
RDX: ffffc900031ff601 RSI: ffffc900031ff998 RDI: 00000000ffffffff
RBP: ffffc900031ff630 R08: dffffc0000000000 R09: ffffc900031ff638
R10: fffff5200063fec9 R11: 1ffff9200063fec7 R12: ffffc900031f8000
R13: dffffc0000000000 R14: ffffc900031ff5f8 R15: ffffc900031ff9a8
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 anon_vma_chain_free mm/rmap.c:143 [inline]
 unlink_anon_vmas+0x2c8/0x660 mm/rmap.c:417
 free_pgtables+0x74/0x2a0 mm/memory.c:412
 exit_mmap+0x39e/0x5f0 mm/mmap.c:3217
 __mmput+0x115/0x3b0 kernel/fork.c:1127
 exit_mm+0x567/0x6c0 kernel/exit.c:550
 do_exit+0x5a1/0x20a0 kernel/exit.c:870
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 __do_sys_exit_group kernel/exit.c:1008 [inline]
 __se_sys_exit_group kernel/exit.c:1006 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
 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: 0033:0x7f25dc622ba9
Code: Unable to access opcode bytes at RIP 0x7f25dc622b7f.
RSP: 002b:00007ffc7023a5a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f25dc622ba9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 000000057023a69f R09: 00007f25dc835280
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f25dc835280 R14: 0000000000000003 R15: 00007ffc7023a660
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/19 02:53 linux-5.15.y 43bb85222e53 e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_exit_group
* Struck through repros no longer work on HEAD.