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From: Thomas Gleixner <tglx@linutronix.de>
To: syzbot <syzbot+a3fcd59df1b372066f5a@syzkaller.appspotmail.com>,
	akpm@linux-foundation.org, bp@alien8.de, hpa@zytor.com,
	jmattson@google.com, joro@8bytes.org, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	mark.rutland@arm.com, masahiroy@kernel.org, mingo@redhat.com,
	pbonzini@redhat.com, peterz@infradead.org,
	rafael.j.wysocki@intel.com, rostedt@goodmis.org,
	seanjc@google.com, sedat.dilek@gmail.com,
	syzkaller-bugs@googlegroups.com, vitor@massaru.org,
	vkuznets@redhat.com, wanpengli@tencent.com, will@kernel.org,
	x86@kernel.org
Subject: Re: [syzbot] general protection fault in try_grab_compound_head
Date: Thu, 08 Jul 2021 15:03:45 +0200	[thread overview]
Message-ID: <87fswpot3i.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <0000000000009e89e205c63dda94@google.com>

On Sat, Jul 03 2021 at 13:24, syzbot wrote:
> syzbot has bisected this issue to:
>
> commit 997acaf6b4b59c6a9c259740312a69ea549cc684
> Author: Mark Rutland <mark.rutland@arm.com>
> Date:   Mon Jan 11 15:37:07 2021 +0000
>
>     lockdep: report broken irq restoration

That's the commit which makes the underlying problem visible:

       raw_local_irq_restore() called with IRQs enabled

and is triggered by this call chain:

 kvm_wait arch/x86/kernel/kvm.c:860 [inline]
 kvm_wait+0xc3/0xe0 arch/x86/kernel/kvm.c:837
 pv_wait arch/x86/include/asm/paravirt.h:564 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x8b8/0xb40 kernel/locking/qspinlock.c:508
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:554 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
 do_raw_spin_lock+0x200/0x2b0 kernel/locking/spinlock_debug.c:113
 spin_lock include/linux/spinlock.h:354 [inline]
 alloc_huge_page+0x2b0/0xda0 mm/hugetlb.c:2318
 hugetlb_no_page mm/hugetlb.c:4323 [inline]
 hugetlb_fault+0xc35/0x1cd0 mm/hugetlb.c:4523
 follow_hugetlb_page+0x317/0xda0 mm/hugetlb.c:4836
 __get_user_pages+0x3fa/0xe30 mm/gup.c:1041
 __get_user_pages_locked mm/gup.c:1256 [inline]
 __gup_longterm_locked+0x15f/0xc80 mm/gup.c:1667
 io_sqe_buffer_register fs/io_uring.c:8462 [inline]
 __io_uring_register fs/io_uring.c:9901 [inline]
 __do_sys_io_uring_register+0xeb1/0x3350 fs/io_uring.c:10000
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Thanks,

        tglx


  reply	other threads:[~2021-07-08 13:11 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-03 15:41 syzbot
2021-07-03 20:24 ` syzbot
2021-07-08 13:03   ` Thomas Gleixner [this message]
2021-07-12 21:29     ` Sean Christopherson
2021-07-13  1:08       ` Joao Martins

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