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INFO: rcu detected stall in userfaultfd_ioctl (3)

Status: auto-obsoleted due to no activity on 2025/11/16 15:21
Subsystems: mm
[Documentation on labels]
First crash: 229d, last: 229d
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in userfaultfd_ioctl mm 1 1 662d 662d 0/29 auto-obsoleted due to no activity on 2024/09/09 20:59
linux-5.15 INFO: rcu detected stall in userfaultfd_ioctl 1 1 639d 639d 0/3 auto-obsoleted due to no activity on 2024/10/12 17:09
linux-6.6 INFO: rcu detected stall in userfaultfd_ioctl 1 1 142d 142d 0/2 auto-obsoleted due to no activity on 2026/02/21 10:46
upstream INFO: rcu detected stall in userfaultfd_ioctl (2) cgroups mm 1 1 448d 448d 0/29 auto-obsoleted due to no activity on 2025/04/11 08:39

Sample crash report:
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6834/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=10437, q=1448 ncpus=2)
task:syz.2.214       state:R  running task     stack:28024 pid:6834  tgid:6815  ppid:5847   task_flags:0x400040 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288
 irqentry_exit+0x36/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__sanitizer_cov_trace_pc+0x46/0x70 kernel/kcov.c:220
Code: 74 1d f6 c4 01 74 43 a9 00 00 0f 00 75 3c a9 00 00 f0 00 75 35 8b 82 3c 16 00 00 85 c0 74 2b 8b 82 18 16 00 00 83 f8 02 75 20 <48> 8b 8a 20 16 00 00 8b 92 1c 16 00 00 48 8b 01 48 83 c0 01 48 39
RSP: 0018:ffffc90003acf878 EFLAGS: 00000246
RAX: 0000000000000002 RBX: 0000000000000000 RCX: ffffffff820f6713
RDX: ffff888045dda440 RSI: ffffffff820f6720 RDI: 0000000000000005
RBP: ffff888078e9b220 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888078e9b221
R13: ffff888078e9b2c0 R14: ffffea0001628050 R15: 0000000000000001
 rcu_lock_release include/linux/rcupdate.h:341 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 folio_get_anon_vma+0xc0/0x760 mm/rmap.c:530
 __folio_split+0x9d4/0x4a80 mm/huge_memory.c:3638
 split_folio_to_list+0x9b/0x180 mm/huge_memory.c:4005
 move_pages_pte mm/userfaultfd.c:1346 [inline]
 move_pages+0x2945/0x5a70 mm/userfaultfd.c:1863
 userfaultfd_move fs/userfaultfd.c:1923 [inline]
 userfaultfd_ioctl+0x607/0x3930 fs/userfaultfd.c:2046
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl fs/ioctl.c:584 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f51edf8ebe9
RSP: 002b:00007f51eede6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f51ee1b6270 RCX: 00007f51edf8ebe9
RDX: 0000200000000100 RSI: 00000000c028aa05 RDI: 0000000000000009
RBP: 00007f51ee011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f51ee1b6308 R14: 00007f51ee1b6270 R15: 00007ffd36849018
 </TASK>
rcu: rcu_preempt kthread starved for 9336 jiffies! g10437 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:28096 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.17.0-rc2-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 7c 62 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 92 16 00 fb f4 <e9> 4c 09 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000197df8 EFLAGS: 000002c2
RAX: 00000000003d6014 RBX: 0000000000000001 RCX: ffffffff8b937c29
RDX: ffffed10170a6656 RSI: ffffffff8c162600 RDI: ffffffff819133c1
RBP: ffffed1003c5d488 R08: 0000000000000000 R09: ffffed10170a6655
R10: ffff8880b85332ab R11: 0000000000000001 R12: 0000000000000001
R13: ffff88801e2ea440 R14: ffffffff90ab3b90 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881247bc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f636a2c7f46 CR3: 000000000e380000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:757
 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x391/0x510 kernel/sched/idle.c:330
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428
 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x148
 </TASK>
net_ratelimit: 31799 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:06:13:c0:c3:f4:37, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:06:13:c0:c3:f4:37, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 43258 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:06:13:c0:c3:f4:37, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:06:13:c0:c3:f4:37, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/18 15:11 upstream c17b750b3ad9 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in userfaultfd_ioctl
* Struck through repros no longer work on HEAD.