INFO: rcu detected stall in asm_exc_page_fault

Status: upstream: reported on 2026/07/19 00:59
Reported-by: syzbot+2e5e664c4a8921206a3e@syzkaller.appspotmail.com
First crash: 23d, last: 23d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in asm_exc_page_fault (2) kasan mm 1 1 290d 290d 0/29 auto-obsoleted due to no activity on 2026/01/22 14:37
linux-5.15 INFO: rcu detected stall in asm_exc_page_fault 1 1 201d 201d 0/3 auto-obsoleted due to no activity on 2026/05/01 14:57
upstream INFO: rcu detected stall in asm_exc_page_fault mm 1 syz error error 4 494d 884d 0/29 auto-obsoleted due to no activity on 2025/07/30 11:21
android-5-15 BUG: soft lockup in asm_exc_page_fault 1 syz, C error 3 708d 856d 0/2 auto-obsoleted due to no activity on 2024/12/10 17:09

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10500 ticks this GP) idle=3ed4/1/0x4000000000000000 softirq=38255/38256 fqs=1158
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:  1420758          5            0
rcu: 	cputime:    13805      37144           43   ==> 50980(ms)
rcu: 	(t=10504 jiffies g=50601 q=2594 ncpus=2)
rcu: rcu_preempt kthread timer wakeup didn't happen for 2809 jiffies! g50601 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=32323
rcu: rcu_preempt kthread starved for 2812 jiffies! g50601 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:26856 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5757 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: 4c 1d 02 c3 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 43 77 3c 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2c 89 cb 80 f9
RSP: 0018:ffffc900044ff6f8 EFLAGS: 000002d3
RAX: ffffffff813a9538 RBX: 0000000000000003 RCX: ffff888076631e00
RDX: 0000000000000000 RSI: ffffffff8acacb60 RDI: ffffffff8b1cfa20
RBP: ffffc900044ff7d0 R08: ffffffff911e75c7 R09: 1ffffffff223ceb8
R10: dffffc0000000000 R11: fffffbfff223ceb9 R12: dffffc0000000000
R13: 0000000000000200 R14: 0000000000000003 R15: 1ffff9200089fee4
FS:  000055557e709500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff4d6fcfe0 CR3: 000000002eb1a000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 kvm_wait+0x23d/0x2a0 arch/x86/kernel/kvm.c:1058
 pv_wait arch/x86/include/asm/paravirt.h:598 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x613/0x9c0 kernel/locking/qspinlock.c:511
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x23e/0x2b0 kernel/locking/spinlock_debug.c:115
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 lock_sock_nested+0x6a/0x100 net/core/sock.c:3547
 lock_sock include/net/sock.h:1780 [inline]
 tcp_recvmsg+0x1fb/0x830 net/ipv4/tcp.c:2607
 inet_recvmsg+0x140/0x1f0 net/ipv4/af_inet.c:882
 sock_recvmsg_nosec net/socket.c:1047 [inline]
 sock_recvmsg net/socket.c:1069 [inline]
 sock_read_iter+0x2db/0x3f0 net/socket.c:1139
 call_read_iter include/linux/fs.h:2012 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x486/0x990 fs/read_write.c:470
 ksys_read+0x151/0x260 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdadb159017
Code: 48 89 fa 4c 89 df e8 a8 56 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffeaf98c010 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000055557e709500 RCX: 00007fdadb159017
RDX: 0000000000000004 RSI: 00007ffeaf98c06c RDI: 0000000000000003
RBP: 00007ffeaf98c510 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000004
R13: 00007ffeaf98c06c R14: 00007ffeaf98c100 R15: 0000000000000000
 </TASK>
CPU: 0 PID: 11448 Comm: syz.0.1657 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:220 [inline]
RIP: 0010:unwind_next_frame+0x281/0x2990 arch/x86/kernel/unwind_orc.c:494
Code: 8f 48 89 e8 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 fd 21 00 00 8b 6d 00 ff c5 4b 8d 04 64 48 8d 8c 00 84 55 0a 8f 48 8d 44 6d 00 <48> 8d 84 00 84 55 0a 8f 48 3d 7c 6d b4 8f 0f 97 c0 48 89 4c 24 20
RSP: 0018:ffffc900000064d8 EFLAGS: 00000202
RAX: 00000000004528ec RBX: dffffc0000000000 RCX: ffffffff8f94a726
RDX: ffff888023bebc00 RSI: 0000000000080f63 RDI: 000000000009c000
RBP: 0000000000170da4 R08: ffffc90000006670 R09: 000000000000000b
R10: 0000000000000004 R11: 0000000000000100 R12: 0000000000170d9b
R13: 000000000009c001 R14: 0000000000080f63 R15: 0000000000000001
FS:  00007f0c5aeb56c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000049aac000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x17e/0x2c0 mm/slub.c:3519
 dst_alloc+0x105/0x170 net/core/dst.c:90
 rt_dst_alloc net/ipv4/route.c:1662 [inline]
 __mkroute_output net/ipv4/route.c:2626 [inline]
 ip_route_output_key_hash_rcu+0x14a2/0x2350 net/ipv4/route.c:2848
 ip_route_output_key_hash+0x1f3/0x330 net/ipv4/route.c:2677
 __ip_route_output_key include/net/route.h:134 [inline]
 ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2905
 ip_route_output_ports include/net/route.h:171 [inline]
 __ip_queue_xmit+0x92e/0x1960 net/ipv4/ip_output.c:496
 __tcp_transmit_skb+0x1dd6/0x3470 net/ipv4/tcp_output.c:1427
 tcp_rcv_established+0x132c/0x1d70 net/ipv4/tcp_input.c:6144
 tcp_v4_do_rcv+0x6d3/0xba0 net/ipv4/tcp_ipv4.c:1735
 tcp_v4_rcv+0x2358/0x2a60 net/ipv4/tcp_ipv4.c:2167
 ip_protocol_deliver_rcu+0x20a/0x3f0 net/ipv4/ip_input.c:205
 ip_local_deliver_finish+0x2c3/0x510 net/ipv4/ip_input.c:233
 NF_HOOK+0x32d/0x3b0 include/linux/netfilter.h:304
 dst_input include/net/dst.h:477 [inline]
 ip_sublist_rcv_finish net/ipv4/ip_input.c:580 [inline]
 ip_list_rcv_finish net/ipv4/ip_input.c:631 [inline]
 ip_sublist_rcv+0xa36/0xd60 net/ipv4/ip_input.c:639
 ip_list_rcv+0x3ed/0x440 net/ipv4/ip_input.c:674
 __netif_receive_skb_list_ptype net/core/dev.c:5689 [inline]
 __netif_receive_skb_list_core+0x2d9/0x770 net/core/dev.c:5727
 __netif_receive_skb_list net/core/dev.c:5789 [inline]
 netif_receive_skb_list_internal+0x943/0xca0 net/core/dev.c:5880
 gro_normal_list include/net/gro.h:451 [inline]
 gro_normal_one include/net/gro.h:464 [inline]
 napi_skb_finish net/core/gro.c:580 [inline]
 napi_gro_receive+0x553/0xaf0 net/core/gro.c:610
 receive_buf+0x219d/0x37a0 drivers/net/virtio_net.c:1870
 virtnet_receive drivers/net/virtio_net.c:2155 [inline]
 virtnet_poll+0x60e/0x11e0 drivers/net/virtio_net.c:2229
 __napi_poll+0xbb/0x460 net/core/dev.c:6650
 napi_poll net/core/dev.c:6717 [inline]
 net_rx_action+0x65f/0xcc0 net/core/dev.c:6853
 handle_softirqs+0x27d/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 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:finish_task_switch+0x267/0x8f0 kernel/sched/core.c:5255
Code: 2e 09 85 c0 0f 84 30 01 00 00 48 85 db 0f 85 4f 01 00 00 0f 1f 44 00 00 4c 89 e7 e8 43 32 38 09 e8 8e 0a 30 00 fb 4c 8b 65 b8 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc900030c7460 EFLAGS: 00000286
RAX: 128e25a5d7537d00 RBX: 0000000000000000 RCX: 128e25a5d7537d00
RDX: dffffc0000000000 RSI: ffffffff8acacb60 RDI: ffffffff8b1cfa20
RBP: ffffc900030c74b0 R08: ffffffff911e7537 R09: 1ffffffff223cea6
R10: dffffc0000000000 R11: fffffbfff223cea7 R12: ffff888023bebc00
R13: 1ffff110171c79a9 R14: dffffc0000000000 R15: ffff8880b8e3cd48
 context_switch kernel/sched/core.c:5384 [inline]
 __schedule+0x15b6/0x4660 kernel/sched/core.c:6700
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x111/0x120 kernel/locking/spinlock.c:194
 rcu_report_exp_rnp kernel/rcu/tree_exp.h:225 [inline]
 rcu_preempt_deferred_qs_irqrestore+0x85e/0xc30 kernel/rcu/tree_plugin.h:570
 rcu_read_unlock_special+0x3ca/0x4d0 kernel/rcu/tree_plugin.h:762
 __rcu_read_unlock+0x7c/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:818 [inline]
 mt_find+0x3fe/0x640 lib/maple_tree.c:6567
 find_vma+0x134/0x1b0 mm/mmap.c:1888
 lock_mm_and_find_vma+0x5f/0x2f0 mm/memory.c:5443
 do_user_addr_fault+0x36b/0x12d0 arch/x86/mm/fault.c:1343
 handle_page_fault arch/x86/mm/fault.c:1463 [inline]
 exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:__put_user_4+0x11/0x20 arch/x86/lib/putuser.S:89
Code: 01 ca c3 90 90 90 90 90 90 f3 0f 1e fa 0f 01 cb 66 89 01 31 c9 0f 01 ca c3 f3 0f 1e fa 48 89 cb 48 c1 fb 3f 48 09 d9 0f 01 cb <89> 01 31 c9 0f 01 ca c3 90 90 90 90 90 90 90 f3 0f 1e fa 0f 01 cb
RSP: 0018:ffffc900030c7e80 EFLAGS: 00050246
RAX: 000000000000000b RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1cfa20
RBP: 000000000000000b R08: ffffffff8e8c6b2f R09: 1ffffffff1d18d65
R10: dffffc0000000000 R11: fffffbfff1d18d66 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
 __sys_socketpair+0xb8/0x550 net/socket.c:1765
 __do_sys_socketpair net/socket.c:1831 [inline]
 __se_sys_socketpair net/socket.c:1828 [inline]
 __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1828
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f0c59f9de99
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0c5aeb5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007f0c5a225fa0 RCX: 00007f0c59f9de99
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 00007f0c5a033eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0c5a226038 R14: 00007f0c5a225fa0 R15: 00007ffd43934a38
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/19 00:58 linux-6.6.y da47cbc25466 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in asm_exc_page_fault
* Struck through repros no longer work on HEAD.