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Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop |
Date: |
Thu, 17 Mar 2016 16:02:30 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 17/03/2016 13:39, Christian Borntraeger wrote:
> As an interesting side note, I updated my system from F20 to F23 some days ago
> (after the initial report). While To Bo is still on a F20 system. I was not
> able
> to reproduce the original crash on f23. but going back to F20 made this
> problem re-appear.
>
> Stack trace of thread 26429:
> #0 0x00000000802008aa tracked_request_begin
> (qemu-system-s390x)
> #1 0x0000000080203f3c bdrv_co_do_preadv (qemu-system-s390x)
> #2 0x000000008020567c bdrv_co_do_readv (qemu-system-s390x)
> #3 0x000000008025d0f4 coroutine_trampoline
> (qemu-system-s390x)
> #4 0x000003ff943d150a __makecontext_ret (libc.so.6)
>
> this is with patch 2-4 plus the removal of virtio_queue_host_notifier_read.
>
> Without removing virtio_queue_host_notifier_read, I get the same mutex lockup
> (as expected).
>
> Maybe we have two independent issues here and this is some old bug in glibc or
> whatever?
I'm happy to try and reproduce on x86 if you give me some instruction
(RHEL7 should be close enough to Fedora 20).
Can you add an assert in virtio_blk_handle_output to catch reentrancy, like
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index a7ec572..96ea896 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -591,6 +591,8 @@ static void virtio_blk_handle_output(VirtIODevice
*vdev, VirtQueue *vq)
return;
}
+ int x = atomic_fetch_inc(&s->test);
+ assert(x == 0);
blk_io_plug(s->blk);
while ((req = virtio_blk_get_request(s))) {
@@ -602,6 +604,7 @@ static void virtio_blk_handle_output(VirtIODevice
*vdev, VirtQueue *vq)
}
blk_io_unplug(s->blk);
+ atomic_dec(&s->test);
}
static void virtio_blk_dma_restart_bh(void *opaque)
diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index ae84d92..6472503 100644
--- a/include/hw/virtio/virtio-blk.h
+++ b/include/hw/virtio/virtio-blk.h
@@ -48,6 +48,7 @@ typedef struct VirtIOBlock {
BlockBackend *blk;
VirtQueue *vq;
void *rq;
+ int test;
QEMUBH *bh;
VirtIOBlkConf conf;
unsigned short sector_mask;
?
Paolo
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, (continued)
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Paolo Bonzini, 2016/03/16
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Fam Zheng, 2016/03/16
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, tu bo, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Fam Zheng, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Fam Zheng, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, tu bo, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Paolo Bonzini, 2016/03/18
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Fam Zheng, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, TU BO, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Paolo Bonzini, 2016/03/21