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[Qemu-devel] [PATCH 29/36] block: Fix AioContext switch for bs->drv == N
From: |
Michael Roth |
Subject: |
[Qemu-devel] [PATCH 29/36] block: Fix AioContext switch for bs->drv == NULL |
Date: |
Tue, 23 Jul 2019 12:00:57 -0500 |
From: Kevin Wolf <address@hidden>
Even for block nodes with bs->drv == NULL, we can't just ignore a
bdrv_set_aio_context() call. Leaving the node in its old context can
mean that it's still in an iothread context in bdrv_close_all() during
shutdown, resulting in an attempted unlock of the AioContext lock which
we don't hold.
This is an example stack trace of a related crash:
#0 0x00007ffff59da57f in raise () at /lib64/libc.so.6
#1 0x00007ffff59c4895 in abort () at /lib64/libc.so.6
#2 0x0000555555b97b1e in error_exit (err=<optimized out>,
msg=msg@entry=0x555555d386d0 <__func__.19059> "qemu_mutex_unlock_impl") at
util/qemu-thread-posix.c:36
#3 0x0000555555b97f7f in qemu_mutex_unlock_impl
(mutex=mutex@entry=0x5555568002f0, file=file@entry=0x555555d378df
"util/async.c", line=line@entry=507) at util/qemu-thread-posix.c:97
#4 0x0000555555b92f55 in aio_context_release (ctx=ctx@entry=0x555556800290)
at util/async.c:507
#5 0x0000555555b05cf8 in bdrv_prwv_co (child=child@entry=0x7fffc80012f0,
offset=offset@entry=131072, qiov=qiov@entry=0x7fffffffd4f0,
is_write=is_write@entry=true, flags=flags@entry=0)
at block/io.c:833
#6 0x0000555555b060a9 in bdrv_pwritev (qiov=0x7fffffffd4f0, offset=131072,
child=0x7fffc80012f0) at block/io.c:990
#7 0x0000555555b060a9 in bdrv_pwrite (child=0x7fffc80012f0, offset=131072,
buf=<optimized out>, bytes=<optimized out>) at block/io.c:990
#8 0x0000555555ae172b in qcow2_cache_entry_flush (bs=bs@entry=0x555556810680,
c=c@entry=0x5555568cc740, i=i@entry=0) at block/qcow2-cache.c:51
#9 0x0000555555ae18dd in qcow2_cache_write (bs=bs@entry=0x555556810680,
c=0x5555568cc740) at block/qcow2-cache.c:248
#10 0x0000555555ae15de in qcow2_cache_flush (bs=0x555556810680, c=<optimized
out>) at block/qcow2-cache.c:259
#11 0x0000555555ae16b1 in qcow2_cache_flush_dependency (c=0x5555568a1700,
c=0x5555568a1700, bs=0x555556810680) at block/qcow2-cache.c:194
#12 0x0000555555ae16b1 in qcow2_cache_entry_flush (bs=bs@entry=0x555556810680,
c=c@entry=0x5555568a1700, i=i@entry=0) at block/qcow2-cache.c:194
#13 0x0000555555ae18dd in qcow2_cache_write (bs=bs@entry=0x555556810680,
c=0x5555568a1700) at block/qcow2-cache.c:248
#14 0x0000555555ae15de in qcow2_cache_flush (bs=bs@entry=0x555556810680,
c=<optimized out>) at block/qcow2-cache.c:259
#15 0x0000555555ad242c in qcow2_inactivate (bs=bs@entry=0x555556810680) at
block/qcow2.c:2124
#16 0x0000555555ad2590 in qcow2_close (bs=0x555556810680) at block/qcow2.c:2153
#17 0x0000555555ab0c62 in bdrv_close (bs=0x555556810680) at block.c:3358
#18 0x0000555555ab0c62 in bdrv_delete (bs=0x555556810680) at block.c:3542
#19 0x0000555555ab0c62 in bdrv_unref (bs=0x555556810680) at block.c:4598
#20 0x0000555555af4d72 in blk_remove_bs (blk=blk@entry=0x5555568103d0) at
block/block-backend.c:785
#21 0x0000555555af4dbb in blk_remove_all_bs () at block/block-backend.c:483
#22 0x0000555555aae02f in bdrv_close_all () at block.c:3412
#23 0x00005555557f9796 in main (argc=<optimized out>, argv=<optimized out>,
envp=<optimized out>) at vl.c:4776
The reproducer I used is a qcow2 image on gluster volume, where the
virtual disk size (4 GB) is larger than the gluster volume size (64M),
so we can easily trigger an ENOSPC. This backend is assigned to a
virtio-blk device using an iothread, and then from the guest a
'dd if=/dev/zero of=/dev/vda bs=1G count=1' causes the VM to stop
because of an I/O error. qemu_gluster_co_flush_to_disk() sets
bs->drv = NULL on error, so when virtio-blk stops the dataplane, the
block nodes stay in the iothread AioContext. A 'quit' monitor command
issued from this paused state crashes the process.
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1631227
Cc: address@hidden
Signed-off-by: Kevin Wolf <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
Reviewed-by: Stefano Garzarella <address@hidden>
(cherry picked from commit 1bffe1ae7a7b707c3a14ea2ccd00d3609d3ce4d8)
*drop context dependency on e64f25f30b8
Signed-off-by: Michael Roth <address@hidden>
---
block.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)
diff --git a/block.c b/block.c
index 1ec4512d1e..3405a652a3 100644
--- a/block.c
+++ b/block.c
@@ -5056,10 +5056,6 @@ void bdrv_detach_aio_context(BlockDriverState *bs)
BdrvAioNotifier *baf, *baf_tmp;
BdrvChild *child;
- if (!bs->drv) {
- return;
- }
-
assert(!bs->walking_aio_notifiers);
bs->walking_aio_notifiers = true;
QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
@@ -5074,7 +5070,7 @@ void bdrv_detach_aio_context(BlockDriverState *bs)
*/
bs->walking_aio_notifiers = false;
- if (bs->drv->bdrv_detach_aio_context) {
+ if (bs->drv && bs->drv->bdrv_detach_aio_context) {
bs->drv->bdrv_detach_aio_context(bs);
}
QLIST_FOREACH(child, &bs->children, next) {
@@ -5090,16 +5086,12 @@ void bdrv_attach_aio_context(BlockDriverState *bs,
BdrvAioNotifier *ban, *ban_tmp;
BdrvChild *child;
- if (!bs->drv) {
- return;
- }
-
bs->aio_context = new_context;
QLIST_FOREACH(child, &bs->children, next) {
bdrv_attach_aio_context(child->bs, new_context);
}
- if (bs->drv->bdrv_attach_aio_context) {
+ if (bs->drv && bs->drv->bdrv_attach_aio_context) {
bs->drv->bdrv_attach_aio_context(bs, new_context);
}
--
2.17.1
- [Qemu-devel] [PATCH 17/36] i386: remove the new CPUID 'PCONFIG' from Icelake-Server CPU model, (continued)
- [Qemu-devel] [PATCH 17/36] i386: remove the new CPUID 'PCONFIG' from Icelake-Server CPU model, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 18/36] i386: remove the 'INTEL_PT' CPUID bit from named CPU models, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 15/36] tpm_tis: fix loop that cancels any seizure by a lower locality, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 16/36] vfio-ap: flag as compatible with balloon, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 20/36] qga-win: include glib when building VSS DLL, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 19/36] json: Fix % handling when not interpolating, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 21/36] configure: improve usbfs check, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 27/36] qcow2: Avoid COW during metadata preallocation, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 25/36] usb-mtp: use O_NOFOLLOW and O_CLOEXEC., Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 28/36] cutils: Fix size_to_str() on 32-bit platforms, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 29/36] block: Fix AioContext switch for bs->drv == NULL,
Michael Roth <=
- [Qemu-devel] [PATCH 24/36] qga: update docs with systemd suspend support info, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 14/36] slirp: check sscanf result when emulating ident, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 26/36] qemu-img: fix error reporting for -object, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 30/36] do not call vhost_net_cleanup() on running net from char user event, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 01/36] i2c: Move typedef of bitbang_i2c_interface to i2c.h, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 22/36] mac_oldworld: use node name instead of alias name for hd device in FWPathProvider, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 23/36] mac_newworld: use node name instead of alias name for hd device in FWPathProvider, Michael Roth, 2019/07/23
- [Qemu-devel] [PATCH 06/36] hw/s390x: Fix bad mask in time2tod(), Michael Roth, 2019/07/23