syzbot


INFO: rcu detected stall in schedule_timeout (2)

Status: upstream: reported on 2025/09/02 23:57
Reported-by: syzbot+7dca4d8f5e1c02ee5ebf@syzkaller.appspotmail.com
First crash: 2d04h, last: 2d04h
Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in schedule_timeout (3) cgroups mm 1 11 2066d 2066d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in schedule_timeout (7) kernel 1 C error error 25 3d16h 299d 0/29 upstream: reported C repro on 2024/11/09 08:24
upstream INFO: rcu detected stall in schedule_timeout (2) kernel 1 2 2066d 2067d 0/29 closed as invalid on 2020/01/08 05:23
upstream INFO: rcu detected stall in schedule_timeout (4) kernel 1 1 772d 772d 0/29 closed as invalid on 2023/09/01 06:44
linux-6.1 INFO: rcu detected stall in schedule_timeout 1 28 439d 505d 0/3 auto-obsoleted due to no activity on 2024/08/31 04:44
upstream INFO: rcu detected stall in schedule_timeout (5) kernel 1 2 677d 712d 0/29 auto-obsoleted due to no activity on 2024/01/26 16:31
upstream INFO: rcu detected stall in schedule_timeout cgroups mm 1 69 2101d 2103d 0/29 closed as invalid on 2019/12/04 14:14
upstream INFO: rcu detected stall in schedule_timeout (6) usb 1 C done 40 319d 476d 28/29 fixed on 2024/10/22 11:57
linux-5.15 INFO: rcu detected stall in schedule_timeout origin:upstream 1 C 9 4d01h 470d 0/3 upstream: reported C repro on 2024/05/22 14:45

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 0, t=10502 jiffies, g=18353, q=36 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294963862-4294953359), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10504 jiffies! g18353 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:27848 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:check_region_inline mm/kasan/generic.c:169 [inline]
RIP: 0010:kasan_check_range+0x2/0x290 mm/kasan/generic.c:189
Code: c6 48 89 c7 e8 0f 0d 47 08 31 c0 c3 0f 0b b8 ea ff ff ff c3 0f 0b b8 ea ff ff ff c3 00 00 cc cc 00 00 cc cc 00 00 cc cc b0 01 <48> 85 f6 0f 84 a4 01 00 00 41 57 41 56 53 49 89 f8 49 01 f0 0f 82
RSP: 0018:ffffc90000157b98 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffff88813fed5940 RCX: ffffffff8a1fe020
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88813fed5940
RBP: ffffc90000157cb0 R08: dffffc0000000000 R09: ffffed10171c7551
R10: ffffed10171c7551 R11: 1ffff110171c7550 R12: 1ffff9200002af78
R13: 1ffffffff1901e40 R14: 1ffff11027fdab28 R15: dffffc0000000000
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 test_ti_thread_flag include/linux/thread_info.h:118 [inline]
 need_resched include/linux/sched.h:2230 [inline]
 schedule+0xd0/0x180 kernel/sched/core.c:6639
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 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:
CPU: 0 PID: 6045 Comm: syz.2.596 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:lock_release+0x593/0x910 kernel/locking/lockdep.c:5686
Code: 00 00 00 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 75 75 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 2f 00 00 00 00 66 43 c7 44 2f 09 00 00 43 c6 44 2f 0b 00
RSP: 0018:ffffc9000dc67dc0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: ffffffffffffffff RCX: c4089029a8d1f300
RDX: 0000000000000000 RSI: ffffffff8a8c1480 RDI: ffffffff8adefae0
RBP: ffffc9000dc67ec8 R08: dffffc0000000000 R09: fffffbfff1c3ee26
R10: fffffbfff1c3ee26 R11: 1ffffffff1c3ee25 R12: ffff88802f9d0ae0
R13: dffffc0000000000 R14: ffff88802f9d0ad0 R15: 1ffff92001b8cfc4
FS:  00007fa8e4dd46c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000005c9df000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rcu_lock_release include/linux/rcupdate.h:355 [inline]
 rcu_read_unlock include/linux/rcupdate.h:824 [inline]
 __task_pid_nr_ns+0x387/0x460 kernel/pid.c:501
 task_tgid_vnr include/linux/sched.h:1628 [inline]
 __ia32_sys_getpid+0x19/0x20 kernel/sys.c:953
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa8e3f85ba7
Code: 0b e9 68 fe ff ff 48 83 c4 18 48 8d 3d f2 6c d7 00 5b 5d 41 5c 41 5d 41 5e 41 5f e9 f3 f7 fb ff 0f 1f 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00
RSP: 002b:00007fa8e4dd3b08 EFLAGS: 00000202 ORIG_RAX: 0000000000000027
RAX: ffffffffffffffda RBX: 00007fa8e4dd3c70 RCX: 00007fa8e3f85ba7
RDX: 00007fa8e4dd3b40 RSI: 00007fa8e4dd3c70 RDI: 0000000000000021
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fa8e41c6038 R14: 00007fff260cc8b0 R15: 00007fff260cc998
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/02 23:56 linux-6.1.y f89b6e15694c 96a211bc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in schedule_timeout
* Struck through repros no longer work on HEAD.