syzbot


INFO: rcu detected stall in kcompactd

Status: upstream: reported on 2024/06/11 19:09
Reported-by: syzbot+8fe93fa0c24bda8ee5c6@syzkaller.appspotmail.com
First crash: 35d, last: 35d
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in kcompactd mm 1 340d 340d 0/27 auto-obsoleted due to no activity on 2023/11/10 08:17
upstream INFO: rcu detected stall in kcompactd (2) mm C error 4 3d08h 46d 0/27 upstream: reported C repro on 2024/06/01 03:17
upstream BUG: soft lockup in kcompactd kvm 1 987d 983d 0/27 auto-closed as invalid on 2022/01/31 12:36

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=13817, q=114 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10500 (4294960527-4294950027), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10500 jiffies! g13817 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:26112 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: 31 Comm: kcompactd1 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:ffffc90000a7f608 EFLAGS: 00000286
RAX: 9d1a03b74b1cbf00 RBX: ffff888077958034 RCX: ffffffff91c94103
RDX: dffffc0000000000 RSI: ffffffff8aec01c0 RDI: ffff888018676f38
RBP: ffffc90000a7f650 R08: dffffc0000000000 R09: ffffed1017327541
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888018675940
R13: 1ffff110173276eb R14: ffff8880b993aa00 R15: ffff8880b993b758
FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32b3f000 CR3: 0000000021dd9000 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:constant_test_bit arch/x86/include/asm/bitops.h:207 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:239 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:test_ti_thread_flag include/linux/thread_info.h:118 [inline]
RIP: 0010:need_resched include/linux/sched.h:2231 [inline]
RIP: 0010:schedule+0xdb/0x180 kernel/sched/core.c:6636
Code: 00 00 e8 48 c9 ca f6 31 ff e8 f1 b9 ff ff bf 01 00 00 00 e8 b7 ca ca f6 4c 89 e7 be 08 00 00 00 e8 3a 85 4e f7 42 80 3c 3b 00 <74> c7 4c 89 e7 e8 9b 83 4e f7 eb bd 4d 89 e6 49 83 c6 2c 4c 89 f0
RSP: 0018:ffffc90000a7f998 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 1ffff110030ceb28 RCX: ffffffff8a938926
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888018675940
RBP: ffffc90000a7fab0 R08: dffffc0000000000 R09: ffffed10030ceb29
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888018675940
R13: 1ffff9200014ff38 R14: ffff888018676bb8 R15: dffffc0000000000
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965
 kcompactd+0x1279/0x28e0 mm/compaction.c:2944
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/11 19:08 linux-6.1.y 88690811da69 4d75f4f7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in kcompactd
* Struck through repros no longer work on HEAD.