syzbot


INFO: rcu detected stall in syscall_enter_from_user_mode (3)

Status: upstream: reported C repro on 2025/02/27 13:22
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+d27661ce10e475e27efe@syzkaller.appspotmail.com
First crash: 185d, last: 11d
Fix bisection: the issue occurs on the latest tested release (bisect log)
Crash: no output from test machine (log)
Repro: syz .config
  
Bug presence (2)
Date Name Commit Repro Result
2025/08/27 linux-6.1.y (ToT) 0bc96de781b4 C [report] INFO: rcu detected stall in perf_event_open
2025/08/27 upstream (ToT) 39f90c196721 C Didn't crash
Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in syscall_enter_from_user_mode (2) 1 1 391d 391d 0/3 auto-obsoleted due to no activity on 2024/11/13 07:03
linux-6.1 INFO: rcu detected stall in syscall_enter_from_user_mode 1 1 788d 788d 0/3 auto-obsoleted due to no activity on 2023/10/13 06:46
upstream INFO: rcu detected stall in syscall_enter_from_user_mode (2) kernel 1 11 964d 1253d 0/29 auto-obsoleted due to no activity on 2023/04/22 11:15
upstream INFO: rcu detected stall in syscall_enter_from_user_mode (3) kernel 1 5 628d 793d 0/29 auto-obsoleted due to no activity on 2024/03/11 14:48
linux-5.15 INFO: rcu detected stall in syscall_enter_from_user_mode missing-backport origin:upstream 1 C done 98 1d07h 628d 0/3 upstream: reported C repro on 2023/12/13 03:22
upstream INFO: rcu detected stall in syscall_enter_from_user_mode kernel 1 2 1310d 1324d 0/29 closed as invalid on 2022/02/08 10:10
android-5-15 BUG: soft lockup in syscall_enter_from_user_mode 1 1 472d 472d 0/2 auto-obsoleted due to no activity on 2024/08/14 14:14
Fix bisection attempts (3)
Created Duration User Patch Repo Result
2025/06/27 04:15 2h09m fix candidate upstream OK (0) job log
2025/06/06 18:47 2h16m bisect fix linux-6.1.y OK (0) job log log
2025/04/07 14:34 2h31m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2654 jiffies s: 5817 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10480 Comm: syz.2.2976 Not tainted 6.1.148-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:lock_acquire+0x218/0x490 kernel/locking/lockdep.c:5666
Code: f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 4b c7 44 3d 00 00 00 00 00 <66> 43 c7 44 3d 09 00 00 43 c6 44 3d 0b 00 65 48 8b 04 25 28 00 00
RSP: 0018:ffffc900000071c0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000000 RCX: b1b2c199b332dc00
RDX: 0000000000000000 RSI: ffffffff8a8c15a0 RDI: ffffffff8adef6a0
RBP: ffffc900000072c8 R08: dffffc0000000000 R09: fffffbfff215bc49
R10: fffffbfff215bc49 R11: 1ffffffff215bc48 R12: 0000000000000000
R13: 1ffff92000000e44 R14: 0000000000000046 R15: dffffc0000000000
FS:  00007fa0197fe6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055557409a808 CR3: 0000000055bca000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 __perf_output_begin kernel/events/ring_buffer.c:163 [inline]
 perf_output_begin_forward+0xb5/0xa80 kernel/events/ring_buffer.c:272
 __perf_event_output kernel/events/core.c:7732 [inline]
 perf_event_output_forward+0x179/0x2a0 kernel/events/core.c:7750
 __perf_event_overflow+0x448/0x610 kernel/events/core.c:9496
 perf_swevent_overflow kernel/events/core.c:9572 [inline]
 perf_swevent_event+0x4ad/0x530 kernel/events/core.c:9610
 perf_tp_event+0x335/0xb60 kernel/events/core.c:10029
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10002
 perf_trace_preemptirq_template+0x287/0x330 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x84/0x500 kernel/rcu/tree_plugin.h:682
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 fd a7 96 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc90000007ac0 EFLAGS: 00000206
RAX: b1b2c199b332dc00 RBX: 1ffff92000000f60 RCX: b1b2c199b332dc00
RDX: dffffc0000000000 RSI: ffffffff8a8c0420 RDI: ffffffff8adef6a0
RBP: ffffc90000007bc0 R08: dffffc0000000000 R09: ffffed10171c6af6
R10: ffffed10171c6af6 R11: 1ffff110171c6af5 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8e3b900 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 ieee80211_rx_napi+0x219/0x3c0 net/mac80211/rx.c:5314
 ieee80211_rx include/net/mac80211.h:4844 [inline]
 ieee80211_handle_queued_frames+0x105/0x1b0 net/mac80211/main.c:317
 tasklet_action_common+0x298/0x400 kernel/softirq.c:826
 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 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:__syscall_enter_from_user_work kernel/entry/common.c:97 [inline]
RIP: 0010:syscall_enter_from_user_mode+0x2a/0x80 kernel/entry/common.c:118
Code: 41 56 53 48 89 f3 49 89 fe 48 8b 7c 24 10 e8 ed fa ff ff 66 90 66 90 e8 54 c3 70 f7 e8 cf c1 70 f7 fb 65 48 8b 05 c6 16 ec 75 <48> 8b 70 08 40 f6 c6 3f 74 0b 4c 89 f7 5b 41 5e e9 b1 6a 57 f7 48
RSP: 0018:ffffc90005687f08 EFLAGS: 00000286
RAX: ffff88805ddd9dc0 RBX: 000000000000012a RCX: b1b2c199b332dc00
RDX: dffffc0000000000 RSI: ffffffff8a8c0420 RDI: ffffffff8adef6a0
RBP: ffffc90005687f48 R08: dffffc0000000000 R09: ffffed10171c6af6
R10: ffffed10171c6af6 R11: 1ffff110171c6af5 R12: 0000000000000000
R13: 0000000000000000 R14: ffffc90005687f58 R15: 0000000000000000
 do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:77
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa01a18ebe9
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:00007fa0197fe038 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007fa01a3b5fa0 RCX: 00007fa01a18ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000140
RBP: 00007fa01a211e19 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa01a3b6038 R14: 00007fa01a3b5fa0 R15: 00007ffc4ea1d0e8
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/20 21:50 linux-6.1.y 0bc96de781b4 0b9605c8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in syscall_enter_from_user_mode
2025/02/27 13:21 linux-6.1.y 3a8358583626 6a8fcbc4 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in syscall_enter_from_user_mode
2025/08/15 07:02 linux-6.1.y 3594f306da12 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in syscall_enter_from_user_mode
* Struck through repros no longer work on HEAD.