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INFO: rcu detected stall in userfaultfd_ioctl

Status: auto-obsoleted due to no activity on 2024/10/12 17:09
Reported-by: syzbot+09a6235122c0944643aa@syzkaller.appspotmail.com
First crash: 526d, last: 526d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in userfaultfd_ioctl (3) mm 1 1 116d 116d 0/29 auto-obsoleted due to no activity on 2025/11/16 15:21
upstream INFO: rcu detected stall in userfaultfd_ioctl mm 1 1 549d 549d 0/29 auto-obsoleted due to no activity on 2024/09/09 20:59
linux-6.6 INFO: rcu detected stall in userfaultfd_ioctl 1 1 29d 29d 0/2 upstream: reported on 2025/11/13 10:46
upstream INFO: rcu detected stall in userfaultfd_ioctl (2) cgroups mm 1 1 335d 335d 0/29 auto-obsoleted due to no activity on 2025/04/11 08:39

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4495/1:b..l
	(detected by 0, t=10502 jiffies, g=14241, q=28)
task:syz.0.234       state:R  running task     stack:25656 pid: 4495 ppid:  3502 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6780
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:lock_acquire+0x252/0x4f0 kernel/locking/lockdep.c:5627
Code: 2b 00 74 08 4c 89 f7 e8 0c 7e 67 00 f6 44 24 61 02 0f 85 84 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc900024a6e60 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92000494dd8 RCX: 1ffff92000494d78
RDX: dffffc0000000000 RSI: ffffffff8a8b3ca0 RDI: ffffffff8ad8f740
RBP: ffffc900024a6fc0 R08: dffffc0000000000 R09: fffffbfff1f7f219
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000494dd4
R13: dffffc0000000000 R14: ffffc900024a6ec0 R15: 0000000000000246
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:312
 rcu_read_lock include/linux/rcupdate.h:739 [inline]
 is_bpf_text_address+0x1d/0x260 kernel/bpf/core.c:721
 kernel_text_address kernel/extable.c:151 [inline]
 __kernel_text_address+0x94/0x100 kernel/extable.c:105
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf3/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x113/0x1c0 kernel/stacktrace.c:122
 save_stack+0xf6/0x1e0 mm/page_owner.c:119
 __set_page_owner+0x37/0x300 mm/page_owner.c:181
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x322a/0x33c0 mm/page_alloc.c:4159
 __alloc_pages+0x272/0x700 mm/page_alloc.c:5423
 alloc_pages_vma+0x39a/0x800 mm/mempolicy.c:2146
 mcopy_atomic_pte mm/userfaultfd.c:137 [inline]
 mfill_atomic_pte mm/userfaultfd.c:485 [inline]
 __mcopy_atomic mm/userfaultfd.c:627 [inline]
 mcopy_atomic+0x80e/0x2020 mm/userfaultfd.c:678
 userfaultfd_copy fs/userfaultfd.c:1722 [inline]
 userfaultfd_ioctl+0x1f9d/0x5820 fs/userfaultfd.c:1996
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f3c9d870bd9
RSP: 002b:00007f3c9c2f1048 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3c9d9fef60 RCX: 00007f3c9d870bd9
RDX: 0000000020000040 RSI: 00000000c028aa03 RDI: 0000000000000004
RBP: 00007f3c9d8dfaa1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f3c9d9fef60 R15: 00007ffeac9e24e8
 </TASK>
rcu: rcu_preempt kthread starved for 10555 jiffies! g14241 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:26712 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:109 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:570

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/04 17:08 linux-5.15.y 4878aadf2d15 3f2748a3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in userfaultfd_ioctl
* Struck through repros no longer work on HEAD.