* [Qemu-devel] [Bug 1813045] [NEW] qemu-ga fsfreeze crashes the kernel
@ 2019-01-23 17:07 Michele Schillaci
2021-04-20 8:04 ` [Bug 1813045] " Thomas Huth
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Michele Schillaci @ 2019-01-23 17:07 UTC (permalink / raw)
To: qemu-devel
Public bug reported:
We use mainly Cloudlinux, Debian and Centos.
We experienced many crashes on our qemu instances based on Cloudlinux during a snapshot.
The issue is not related to CloudLinux directly, but to Qemu agent, which does not freeze the file system(s) correctly. What is actually happening:
When VM backup is invoked, Qemu agent freezes the file systems, so no single change will be made during the backup. But Qemu agent does not respect the loop* devices in freezing order (we have checked its sources), which leads to the next situation:
1) freeze loopback fs
---> send async reqs to loopback thread
2) freeze main fs
3) loopback thread wakes up and trying to write data to the main fs, which is still frozen, and this finally leads to the hung task and kernel crash.
I believe this is the culprit:
/dev/loop0 /tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
/dev/loop0 /var/tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
** Affects: qemu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1813045
Title:
qemu-ga fsfreeze crashes the kernel
Status in QEMU:
New
Bug description:
We use mainly Cloudlinux, Debian and Centos.
We experienced many crashes on our qemu instances based on Cloudlinux during a snapshot.
The issue is not related to CloudLinux directly, but to Qemu agent, which does not freeze the file system(s) correctly. What is actually happening:
When VM backup is invoked, Qemu agent freezes the file systems, so no single change will be made during the backup. But Qemu agent does not respect the loop* devices in freezing order (we have checked its sources), which leads to the next situation:
1) freeze loopback fs
---> send async reqs to loopback thread
2) freeze main fs
3) loopback thread wakes up and trying to write data to the main fs, which is still frozen, and this finally leads to the hung task and kernel crash.
I believe this is the culprit:
/dev/loop0 /tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
/dev/loop0 /var/tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1813045/+subscriptions
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug 1813045] Re: qemu-ga fsfreeze crashes the kernel
2019-01-23 17:07 [Qemu-devel] [Bug 1813045] [NEW] qemu-ga fsfreeze crashes the kernel Michele Schillaci
@ 2021-04-20 8:04 ` Thomas Huth
2021-06-20 4:17 ` Launchpad Bug Tracker
2021-08-09 9:43 ` Thomas Huth
2 siblings, 0 replies; 4+ messages in thread
From: Thomas Huth @ 2021-04-20 8:04 UTC (permalink / raw)
To: qemu-devel
The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now.
If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience.
** Changed in: qemu
Status: New => Incomplete
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https://bugs.launchpad.net/bugs/1813045
Title:
qemu-ga fsfreeze crashes the kernel
Status in QEMU:
Incomplete
Bug description:
We use mainly Cloudlinux, Debian and Centos.
We experienced many crashes on our qemu instances based on Cloudlinux during a snapshot.
The issue is not related to CloudLinux directly, but to Qemu agent, which does not freeze the file system(s) correctly. What is actually happening:
When VM backup is invoked, Qemu agent freezes the file systems, so no single change will be made during the backup. But Qemu agent does not respect the loop* devices in freezing order (we have checked its sources), which leads to the next situation:
1) freeze loopback fs
---> send async reqs to loopback thread
2) freeze main fs
3) loopback thread wakes up and trying to write data to the main fs, which is still frozen, and this finally leads to the hung task and kernel crash.
I believe this is the culprit:
/dev/loop0 /tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
/dev/loop0 /var/tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1813045/+subscriptions
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug 1813045] Re: qemu-ga fsfreeze crashes the kernel
2019-01-23 17:07 [Qemu-devel] [Bug 1813045] [NEW] qemu-ga fsfreeze crashes the kernel Michele Schillaci
2021-04-20 8:04 ` [Bug 1813045] " Thomas Huth
@ 2021-06-20 4:17 ` Launchpad Bug Tracker
2021-08-09 9:43 ` Thomas Huth
2 siblings, 0 replies; 4+ messages in thread
From: Launchpad Bug Tracker @ 2021-06-20 4:17 UTC (permalink / raw)
To: qemu-devel
[Expired for QEMU because there has been no activity for 60 days.]
** Changed in: qemu
Status: Incomplete => Expired
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You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1813045
Title:
qemu-ga fsfreeze crashes the kernel
Status in QEMU:
Expired
Bug description:
We use mainly Cloudlinux, Debian and Centos.
We experienced many crashes on our qemu instances based on Cloudlinux during a snapshot.
The issue is not related to CloudLinux directly, but to Qemu agent, which does not freeze the file system(s) correctly. What is actually happening:
When VM backup is invoked, Qemu agent freezes the file systems, so no single change will be made during the backup. But Qemu agent does not respect the loop* devices in freezing order (we have checked its sources), which leads to the next situation:
1) freeze loopback fs
---> send async reqs to loopback thread
2) freeze main fs
3) loopback thread wakes up and trying to write data to the main fs, which is still frozen, and this finally leads to the hung task and kernel crash.
I believe this is the culprit:
/dev/loop0 /tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
/dev/loop0 /var/tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1813045/+subscriptions
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug 1813045] Re: qemu-ga fsfreeze crashes the kernel
2019-01-23 17:07 [Qemu-devel] [Bug 1813045] [NEW] qemu-ga fsfreeze crashes the kernel Michele Schillaci
2021-04-20 8:04 ` [Bug 1813045] " Thomas Huth
2021-06-20 4:17 ` Launchpad Bug Tracker
@ 2021-08-09 9:43 ` Thomas Huth
2 siblings, 0 replies; 4+ messages in thread
From: Thomas Huth @ 2021-08-09 9:43 UTC (permalink / raw)
To: qemu-devel
See also https://gitlab.com/qemu-project/qemu/-/issues/520
** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #520
https://gitlab.com/qemu-project/qemu/-/issues/520
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You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1813045
Title:
qemu-ga fsfreeze crashes the kernel
Status in QEMU:
Expired
Bug description:
We use mainly Cloudlinux, Debian and Centos.
We experienced many crashes on our qemu instances based on Cloudlinux during a snapshot.
The issue is not related to CloudLinux directly, but to Qemu agent, which does not freeze the file system(s) correctly. What is actually happening:
When VM backup is invoked, Qemu agent freezes the file systems, so no single change will be made during the backup. But Qemu agent does not respect the loop* devices in freezing order (we have checked its sources), which leads to the next situation:
1) freeze loopback fs
---> send async reqs to loopback thread
2) freeze main fs
3) loopback thread wakes up and trying to write data to the main fs, which is still frozen, and this finally leads to the hung task and kernel crash.
I believe this is the culprit:
/dev/loop0 /tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
/dev/loop0 /var/tmp ext3 rw,nosuid,noexec,relatime,data=ordered 0 0
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1813045/+subscriptions
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-08-09 9:51 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-01-23 17:07 [Qemu-devel] [Bug 1813045] [NEW] qemu-ga fsfreeze crashes the kernel Michele Schillaci
2021-04-20 8:04 ` [Bug 1813045] " Thomas Huth
2021-06-20 4:17 ` Launchpad Bug Tracker
2021-08-09 9:43 ` Thomas Huth
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