From: Launchpad Bug Tracker <1054180@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [Bug 1054180] Re: DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu
Date: Sat, 21 Oct 2017 04:17:25 -0000 [thread overview]
Message-ID: <150855944596.6142.2750054834077280201.malone@loganberry.canonical.com> (raw)
In-Reply-To: 20120921161324.22633.34633.malonedeb@chaenomeles.canonical.com
[Expired for QEMU because there has been no activity for 60 days.]
** Changed in: qemu
Status: Incomplete => Expired
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1054180
Title:
DNS activity in slirp (user networking) mode quickly depletes file
descriptors and crashes qemu
Status in QEMU:
Expired
Bug description:
Hi, we have encountered quite some trouble with filedescriptor
depletion of the qemu process. We have figured out that it can be
demonstrated easily by doing a lot of DNS queries inside the VM -- in
our real world scenario this is caused by running centos network
install with a fast mirror.
This situation is further problematic because qemu can't handle fd depletion very well:
1) if ulimit is 1024 then qemu hangs in infinite loop whenever it tries to open the 1025th fd
2) setting ulimit >1024 does not help that much because qemu uses select and max. fd set size is 1024 per default => qemu crashes because of buffer overflow in select()
3) setting ulimit > 1024 AND recompiling with large enough fd set size AND disabling gcc's fortify source seems to work, but that's really just a hot-fix
The problem can be replicated quite easily by running something like
while :; do echo >/dev/udp/10.0.2.3/53; done
inside a Linux VM -- crash comes very soon.
This problem is present in current qemu (1.2.0) and in earlier as
well.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1054180/+subscriptions
prev parent reply other threads:[~2017-10-21 4:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-21 16:13 [Qemu-devel] [Bug 1054180] [NEW] DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu Michal Svoboda
2017-08-21 7:47 ` [Qemu-devel] [Bug 1054180] " Thomas Huth
2017-08-21 7:48 ` Thomas Huth
2017-10-21 4:17 ` Launchpad Bug Tracker [this message]
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=150855944596.6142.2750054834077280201.malone@loganberry.canonical.com \
--to=1054180@bugs.launchpad.net \
--cc=qemu-devel@nongnu.org \
/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.