From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Like Xu <like.xu.linux@gmail.com>
Subject: Re: [PATCH] KVM: x86: Reacquire kvm->srcu in vcpu_run() if exiting on pending signal
Date: Thu, 24 Feb 2022 20:49:09 +0000 [thread overview]
Message-ID: <YhfvRRa56qQR9w5K@google.com> (raw)
In-Reply-To: <20220224190609.3464071-1-seanjc@google.com>
On Thu, Feb 24, 2022, Sean Christopherson wrote:
> Reacquire kvm->srcu in vcpu_run() before returning to the caller if srcu
> was dropped to handle pending work. If the task receives a signal, KVM
> will exit without reacquiring kvm->srcu, resulting in an unbalanced
> unlock kvm_arch_vcpu_ioctl_run(), and eventually hung tasks.
>
> =====================================
> WARNING: bad unlock balance detected!
> 5.17.0-rc3+ #749 Not tainted
> -------------------------------------
> CPU 0/KVM/1803 is trying to release lock (&kvm->srcu) at:
> [<ffffffff81042a19>] kvm_arch_vcpu_ioctl_run+0x669/0x1f60
> but there are no more locks to release!
>
> other info that might help us debug this:
> 1 lock held by CPU 0/KVM/1803:
> #0: ffff88810489c0b0 (&vcpu->mutex){....}-{3:3}, at: kvm_vcpu_ioctl+0x77/0x690
>
> stack backtrace:
> CPU: 7 PID: 1803 Comm: CPU 0/KVM Not tainted 5.17.0-rc3+ #749
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
> Call Trace:
> <TASK>
> dump_stack_lvl+0x34/0x44
> lock_release+0x1b4/0x240
> kvm_arch_vcpu_ioctl_run+0x680/0x1f60
> kvm_vcpu_ioctl+0x279/0x690
> __x64_sys_ioctl+0x83/0xb0
> do_syscall_64+0x3b/0xc0
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> </TASK>
> INFO: task stable:2347 blocked for more than 120 seconds.
> Not tainted 5.17.0-rc3+ #749
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:stable state:D stack: 0 pid: 2347 ppid: 2340 flags:0x00000000
> Call Trace:
> <TASK>
> __schedule+0x328/0xa00
> schedule+0x44/0xb0
> schedule_timeout+0x26f/0x300
> wait_for_completion+0x84/0xe0
> __synchronize_srcu.part.0+0x7a/0xa0
> kvm_swap_active_memslots+0x141/0x180
> kvm_set_memslot+0x2f9/0x470
> kvm_set_memory_region+0x29/0x40
> kvm_vm_ioctl+0x2c3/0xd70
> __x64_sys_ioctl+0x83/0xb0
> do_syscall_64+0x3b/0xc0
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> </TASK>
> INFO: lockdep is turned off.
Ugh, the task hung is actually a different mess introduced by the same patch.
I suspect I'm hitting the one Like reported.
I'll get a fix posted shortly...
next prev parent reply other threads:[~2022-02-24 20:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-24 19:06 [PATCH] KVM: x86: Reacquire kvm->srcu in vcpu_run() if exiting on pending signal Sean Christopherson
2022-02-24 20:49 ` Sean Christopherson [this message]
-- strict thread matches above, loose matches on Subject: below --
2022-02-25 9:59 Paolo Bonzini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YhfvRRa56qQR9w5K@google.com \
--to=seanjc@google.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=like.xu.linux@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.