syzbot


INFO: rcu detected stall in sys_epoll_pwait

Status: upstream: reported on 2024/04/03 16:19
Reported-by: syzbot+d515b86eb46bfbd47898@syzkaller.appspotmail.com
First crash: 73d, last: 19d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_epoll_pwait kernel 1 198d 198d 0/27 auto-obsoleted due to no activity on 2024/01/28 17:58

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=27349, q=19 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10500 (4294966468-4294955968), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10500 jiffies! g27349 f0x2 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:27224 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x142d/0x4550 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 3555 Comm: syz-fuzzer Not tainted 6.1.92-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:finish_task_switch+0x1d3/0x810 kernel/sched/core.c:5124
Code: 37 0b 00 48 83 c4 08 4c 89 f7 e8 98 30 00 00 0f 1f 44 00 00 4c 89 f7 e8 7b 20 36 09 e8 36 26 32 00 fb 49 8d bc 24 f8 15 00 00 <48> 89 f8 48 c1 e8 03 49 bd 00 00 00 00 00 fc ff df 42 0f b6 04 28
RSP: 0018:ffffc90003aff668 EFLAGS: 00000286
RAX: dbfd10445fbe5700 RBX: ffff888056761df4 RCX: ffffffff91c94103
RDX: dffffc0000000000 RSI: ffffffff8aec01c0 RDI: ffff888028daef38
RBP: ffffc90003aff6b0 R08: dffffc0000000000 R09: ffffed1017327541
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888028dad940
R13: 1ffff110173276eb R14: ffff8880b993aa00 R15: ffff8880b993b758
FS:  000000c000302890(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32929000 CR3: 000000001ecd8000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 </IRQ>
 <TASK>
 context_switch kernel/sched/core.c:5248 [inline]
 __schedule+0x1435/0x4550 kernel/sched/core.c:6558
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870
 irqentry_exit+0x53/0x80 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:653
RIP: 0010:preempt_count_add+0x4/0x180 kernel/sched/core.c:5698
Code: 80 e1 07 80 c1 03 38 c1 7c 97 48 8b 3c 24 e8 83 ba 83 00 eb 8c e9 f2 fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 66 90 41 57 41 56 <53> 89 fb 48 c7 c0 60 41 c9 91 48 c1 e8 03 49 bf 00 00 00 00 00 fc
RSP: 0018:ffffc90003affa00 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 1ffff110051b5b28 RCX: ffffffff8a938926
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000001
RBP: ffffc90003affb50 R08: dffffc0000000000 R09: ffffed10051b5b29
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888028dad940
R13: 1ffff9200075ff4c R14: ffff888028daebb8 R15: dffffc0000000000
 schedule+0xb8/0x180 kernel/sched/core.c:6633
 schedule_hrtimeout_range_clock+0x2a4/0x480 kernel/time/hrtimer.c:2308
 ep_poll fs/eventpoll.c:1884 [inline]
 do_epoll_wait+0x1be9/0x1e60 fs/eventpoll.c:2262
 do_epoll_pwait+0x56/0x1d0 fs/eventpoll.c:2296
 __do_sys_epoll_pwait fs/eventpoll.c:2309 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2303 [inline]
 __x64_sys_epoll_pwait+0x2b4/0x300 fs/eventpoll.c:2303
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x40720e
Code: 48 83 ec 38 e8 13 00 00 00 48 83 c4 38 5d c3 cc cc cc cc cc cc cc cc cc cc cc cc cc 49 89 f2 48 89 fa 48 89 ce 48 89 df 0f 05 <48> 3d 01 f0 ff ff 76 15 48 f7 d8 48 89 c1 48 c7 c0 ff ff ff ff 48
RSP: 002b:000000c00008b748 EFLAGS: 00000246 ORIG_RAX: 0000000000000119
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000040720e
RDX: 0000000000000080 RSI: 000000c00008b818 RDI: 0000000000000004
RBP: 000000c00008b790 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000010e R11: 0000000000000246 R12: 000000c00008b820
R13: fffff01ef111111e R14: 000000c000fd1040 R15: 00000000000000ca
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/27 03:12 linux-6.1.y 88690811da69 a10a183e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_epoll_pwait
2024/04/03 16:18 linux-6.1.y 347385861c50 51c4dcff .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_epoll_pwait
* Struck through repros no longer work on HEAD.