[v5.15] INFO: rcu detected stall in userfaultfd_ioctl

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4878aadf2d15 Linux 5.15.161
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16b79976980000
kernel config: https://syzkaller.appspot.com/x/.config?x=875d98826c53bf16
dashboard link: https://syzkaller.appspot.com/bug?extid=09a6235122c0944643aa
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f227a150ea92/disk-4878aadf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6cfc50bf8b4e/vmlinux-4878aadf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/23f7adc3c761/bzImage-4878aadf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+09a623...@syzkaller.appspotmail.com

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


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