[Bug 1923583] [NEW] colo: pvm flush failed after svm killed

meeho yuen posted 1 patch 1 year, 5 months ago
Test checkpatch failed
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/161830261172.29345.7866671962411605196.malonedeb@wampee.canonical.com
Maintainers: Kevin Wolf <kwolf@redhat.com>, Alberto Garcia <berto@igalia.com>, Max Reitz <mreitz@redhat.com>
[Bug 1923583] [NEW] colo: pvm flush failed after svm killed
Posted by meeho yuen 1 year, 5 months ago
Public bug reported:

Hi,
   Primary vm flush failed after killing svm, which leads primary vm guest filesystem unavailable.

qemu versoin: 5.2.0
host/guest os: CentOS Linux release 7.6.1810 (Core)

Reproduce steps:
1. create colo vm following https://github.com/qemu/qemu/blob/master/docs/COLO-FT.txt
2. kill secondary vm (don't remove nbd child from quorum on primary vm)and wait for a minute. the interval depends on guest os.
result: primary vm file system shutdown because of flush cache error.

After serveral tests, I found that qemu-5.0.0 worked well, and it's the
commit
https://git.qemu.org/?p=qemu.git;a=commit;h=883833e29cb800b4d92b5d4736252f4004885191(block:
Flush all children in generic code) leads this change, and both virtio-
blk and ide turned out to be bad.

I think it's nbd(replication) flush failed leads bdrv_co_flush(quorum_bs) failed, here is the call stack.
#0  bdrv_co_flush (bs=0x56242b3cc0b0=nbd_bs) at ../block/io.c:2856
#1  0x0000562428b0f399 in bdrv_co_flush (bs=0x56242b3c7e00=replication_bs) at ../block/io.c:2920
#2  0x0000562428b0f399 in bdrv_co_flush (bs=0x56242a4ad800=quorum_bs) at ../block/io.c:2920
#3  0x0000562428b70d56 in blk_do_flush (blk=0x56242a4ad4a0) at ../block/block-backend.c:1672
#4  0x0000562428b70d87 in blk_aio_flush_entry (opaque=0x7fd0980073f0) at ../block/block-backend.c:1680
#5  0x0000562428c5f9a7 in coroutine_trampoline (i0=-1409269904, i1=32721) at ../util/coroutine-ucontext.c:173

While i am not sure whether i use colo inproperly? Can we assume that
nbd child of quorum immediately removed right after svm crashed? Or it's
really a bug? Does the following patch fix? Help is needed! Thanks a
lot!

diff --git a/block/quorum.c b/block/quorum.c
index cfc1436..f2c0805 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1279,7 +1279,7 @@ static BlockDriver bdrv_quorum = {
     .bdrv_dirname                       = quorum_dirname,
     .bdrv_co_block_status               = quorum_co_block_status,
 
-    .bdrv_co_flush_to_disk              = quorum_co_flush,
+    .bdrv_co_flush                      = quorum_co_flush,
 
     .bdrv_getlength                     = quorum_getlength,

** Affects: qemu
     Importance: Undecided
         Status: New

** Patch added: "primary guest kernel message"
   https://bugs.launchpad.net/bugs/1923583/+attachment/5487235/+files/primary_guest_dmesg.log

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1923583

Title:
  colo: pvm flush failed after svm killed

Status in QEMU:
  New

Bug description:
  Hi,
     Primary vm flush failed after killing svm, which leads primary vm guest filesystem unavailable.

  qemu versoin: 5.2.0
  host/guest os: CentOS Linux release 7.6.1810 (Core)

  Reproduce steps:
  1. create colo vm following https://github.com/qemu/qemu/blob/master/docs/COLO-FT.txt
  2. kill secondary vm (don't remove nbd child from quorum on primary vm)and wait for a minute. the interval depends on guest os.
  result: primary vm file system shutdown because of flush cache error.

  After serveral tests, I found that qemu-5.0.0 worked well, and it's
  the commit
  https://git.qemu.org/?p=qemu.git;a=commit;h=883833e29cb800b4d92b5d4736252f4004885191(block:
  Flush all children in generic code) leads this change, and both
  virtio-blk and ide turned out to be bad.

  I think it's nbd(replication) flush failed leads bdrv_co_flush(quorum_bs) failed, here is the call stack.
  #0  bdrv_co_flush (bs=0x56242b3cc0b0=nbd_bs) at ../block/io.c:2856
  #1  0x0000562428b0f399 in bdrv_co_flush (bs=0x56242b3c7e00=replication_bs) at ../block/io.c:2920
  #2  0x0000562428b0f399 in bdrv_co_flush (bs=0x56242a4ad800=quorum_bs) at ../block/io.c:2920
  #3  0x0000562428b70d56 in blk_do_flush (blk=0x56242a4ad4a0) at ../block/block-backend.c:1672
  #4  0x0000562428b70d87 in blk_aio_flush_entry (opaque=0x7fd0980073f0) at ../block/block-backend.c:1680
  #5  0x0000562428c5f9a7 in coroutine_trampoline (i0=-1409269904, i1=32721) at ../util/coroutine-ucontext.c:173

  While i am not sure whether i use colo inproperly? Can we assume that
  nbd child of quorum immediately removed right after svm crashed? Or
  it's really a bug? Does the following patch fix? Help is needed!
  Thanks a lot!

  diff --git a/block/quorum.c b/block/quorum.c
  index cfc1436..f2c0805 100644
  --- a/block/quorum.c
  +++ b/block/quorum.c
  @@ -1279,7 +1279,7 @@ static BlockDriver bdrv_quorum = {
       .bdrv_dirname                       = quorum_dirname,
       .bdrv_co_block_status               = quorum_co_block_status,
   
  -    .bdrv_co_flush_to_disk              = quorum_co_flush,
  +    .bdrv_co_flush                      = quorum_co_flush,
   
       .bdrv_getlength                     = quorum_getlength,

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1923583/+subscriptions

Re: [Bug 1923583] [NEW] colo: pvm flush failed after svm killed
Posted by no-reply@patchew.org 1 year, 5 months ago
Patchew URL: https://patchew.org/QEMU/161830261172.29345.7866671962411605196.malonedeb@wampee.canonical.com/



Hi,

This series seems to have some coding style problems. See output below for
more information:

Type: series
Message-id: 161830261172.29345.7866671962411605196.malonedeb@wampee.canonical.com
Subject: [Bug 1923583] [NEW] colo: pvm flush failed after svm killed

=== TEST SCRIPT BEGIN ===
#!/bin/bash
git rev-parse base > /dev/null || exit 0
git config --local diff.renamelimit 0
git config --local diff.renames True
git config --local diff.algorithm histogram
./scripts/checkpatch.pl --mailback base..
=== TEST SCRIPT END ===

Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
From https://github.com/patchew-project/qemu
 * [new tag]         patchew/161830261172.29345.7866671962411605196.malonedeb@wampee.canonical.com -> patchew/161830261172.29345.7866671962411605196.malonedeb@wampee.canonical.com
 - [tag update]      patchew/20210413081008.3409459-1-f4bug@amsat.org -> patchew/20210413081008.3409459-1-f4bug@amsat.org
Switched to a new branch 'test'
f43885d colo: pvm flush failed after svm killed

=== OUTPUT BEGIN ===
ERROR: Missing Signed-off-by: line(s)

total: 1 errors, 0 warnings, 8 lines checked

Commit f43885d3a7e9 (colo: pvm flush failed after svm killed) has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.
=== OUTPUT END ===

Test command exited with code: 1


The full log is available at
http://patchew.org/logs/161830261172.29345.7866671962411605196.malonedeb@wampee.canonical.com/testing.checkpatch/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com