syzbot


INFO: rcu detected stall in sys_openat

Status: upstream: reported on 2025/07/10 07:34
Reported-by: syzbot+6d93f26ac7a5c42350ec@syzkaller.appspotmail.com
First crash: 14d, last: 14d
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in sys_openat 1 3 686d 719d 0/3 auto-obsoleted due to no activity on 2023/12/16 21:24
upstream INFO: rcu detected stall in sys_openat exfat 1 5 2384d 2462d 0/29 closed as dup on 2018/10/27 13:02
linux-5.15 INFO: rcu detected stall in sys_openat missing-backport origin:upstream 1 C done 35 31d 766d 0/3 upstream: reported C repro on 2023/06/19 20:52
linux-6.1 INFO: rcu detected stall in sys_openat (2) origin:upstream 1 C error 15 52d 498d 0/3 upstream: reported C repro on 2024/03/13 11:37
upstream INFO: rcu detected stall in sys_openat (3) mm 1 C error 426 18h42m 690d 0/29 upstream: reported C repro on 2023/09/03 11:10
upstream INFO: rcu detected stall in sys_openat (2) kernfs 1 8 1266d 1478d 0/29 closed as invalid on 2022/02/08 09:50
android-5-15 BUG: soft lockup in sys_openat (2) origin:lts 1 C error 5 317d 367d 0/2 auto-obsoleted due to no activity on 2024/12/19 09:52
android-5-15 BUG: soft lockup in sys_openat 1 21 418d 473d 0/2 auto-obsoleted due to no activity on 2024/07/21 23:03

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=bad4/1/0x4000000000000000 softirq=69347/69358 fqs=76
rcu: 	(detected by 1, t=10502 jiffies, g=86549, q=72 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 20108 Comm: syz.1.3588 Not tainted 6.6.96-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:check_preemption_disabled+0x47/0x110 lib/smp_processor_id.c:55
Code: 95 75 65 8b 0d c2 3c 95 75 f7 c1 ff ff ff 7f 74 1f 65 48 8b 0c 25 28 00 00 00 48 3b 4c 24 08 0f 85 c4 00 00 00 48 83 c4 10 5b <41> 5e 41 5f 5d c3 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00
RSP: 0018:ffffc90000007aa0 EFLAGS: 00000082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: c7e717330e077200
RDX: 0000000000000000 RSI: ffffffff8afc6ce0 RDI: ffffffff8afc6ca0
RBP: ffffc90000007bf0 R08: ffffffff8e4a7faf R09: 1ffffffff1c94ff5
R10: dffffc0000000000 R11: fffffbfff1c94ff6 R12: ffffffff84267507
R13: dffffc0000000000 R14: ffffffff970c3af8 R15: 1ffff92000000f68
FS:  00007fc33dfde6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3cabd8 CR3: 0000000031cbd000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline]
 rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:700
 trace_lock_release include/trace/events/lock.h:69 [inline]
 lock_release+0xba/0x8b0 kernel/locking/lockdep.c:5765
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline]
 _raw_spin_unlock_irqrestore+0x71/0x110 kernel/locking/spinlock.c:194
 debug_object_activate+0x2f7/0x4b0 lib/debugobjects.c:727
 debug_hrtimer_activate kernel/time/hrtimer.c:450 [inline]
 debug_activate kernel/time/hrtimer.c:505 [inline]
 enqueue_hrtimer+0x30/0x370 kernel/time/hrtimer.c:1113
 __run_hrtimer kernel/time/hrtimer.c:1772 [inline]
 __hrtimer_run_queues+0x637/0xc40 kernel/time/hrtimer.c:1819
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1881
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:preempt_schedule_irq+0xb0/0x140 kernel/sched/core.c:7010
Code: 44 24 20 f6 44 24 21 02 74 0b 0f 0b 48 f7 03 08 00 00 00 74 63 bf 01 00 00 00 e8 2b b2 e4 f6 e8 56 49 15 f7 fb bf 01 00 00 00 <e8> 2b b5 ff ff 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 8b 44 24
RSP: 0018:ffffc90004fe7660 EFLAGS: 00000286
RAX: c7e717330e077200 RBX: 0000000000000000 RCX: c7e717330e077200
RDX: dffffc0000000000 RSI: ffffffff8aaab2c0 RDI: 0000000000000001
RBP: ffffc90004fe7710 R08: ffffffff8e4a7faf R09: 1ffffffff1c94ff5
R10: dffffc0000000000 R11: fffffbfff1c94ff6 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff920009fcecc
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:692
RIP: 0010:try_charge_memcg+0x0/0x1810 mm/memcontrol.c:2642
Code: c8 0f 85 4f ff ff ff 48 89 df 48 c7 c6 a0 d3 b6 8a e8 d4 9e e0 ff 0f 0b 48 89 df 48 c7 c6 20 d4 b6 8a e8 c3 9e e0 ff 0f 0b 90 <f3> 0f 1e fa 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48
RSP: 0018:ffffc90004fe77d8 EFLAGS: 00000246
RAX: ffff888024bf6000 RBX: dffffc0000000000 RCX: c7e717330e077200
RDX: 0000000000000001 RSI: 0000000000000dc0 RDI: ffff888024bf6000
RBP: ffffc90004fe78e0 R08: ffffffff8e4a7faf R09: 1ffffffff1c94ff5
R10: dffffc0000000000 R11: fffffbfff1c94ff6 R12: 0000000000000000
R13: ffff888024bf6000 R14: 0000000000000001 R15: 1ffff920009fcf04
 obj_cgroup_charge_pages mm/memcontrol.c:3109 [inline]
 obj_cgroup_charge+0x358/0x620 mm/memcontrol.c:3400
 memcg_slab_pre_alloc_hook mm/slab.h:508 [inline]
 slab_pre_alloc_hook+0x2eb/0x310 mm/slab.h:719
 slab_alloc_node mm/slub.c:3467 [inline]
 slab_alloc mm/slub.c:3493 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3500 [inline]
 kmem_cache_alloc+0x5a/0x2e0 mm/slub.c:3509
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 alloc_empty_file+0x9e/0x1d0 fs/file_table.c:206
 path_openat+0x100/0x3190 fs/namei.c:3775
 do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
 do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
 do_sys_open fs/open.c:1434 [inline]
 __do_sys_openat fs/open.c:1450 [inline]
 __se_sys_openat fs/open.c:1445 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1445
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc33e18e929
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:00007fc33dfde038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fc33e3b6160 RCX: 00007fc33e18e929
RDX: 0000000000000000 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007fc33e210b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc33e3b6160 R15: 00007ffd5387d8d8
 </TASK>
rcu: rcu_preempt kthread starved for 10350 jiffies! g86549 f0x0 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:27240 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14e2/0x4580 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.6.96-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148
Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d c3 bf 39 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56
RSP: 0018:ffffc90000187de0 EFLAGS: 000002c2
RAX: 9fe3dfa50aaf5200 RBX: ffffffff81618a7b RCX: 9fe3dfa50aaf5200
RDX: 0000000000000001 RSI: ffffffff8aaab2c0 RDI: ffffffff8afc6d00
RBP: ffffc90000187f20 R08: ffff8880b8f36d4b R09: 1ffff110171e6da9
R10: dffffc0000000000 R11: ffffed10171e6daa R12: ffffffff8e4a7fa8
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff1100364e780
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e51fffc CR3: 00000000238dc000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:170 [inline]
 do_idle+0x1eb/0x510 kernel/sched/idle.c:282
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/10 07:33 linux-6.6.y a5df3a702b2c 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_openat
* Struck through repros no longer work on HEAD.