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Diffstat (limited to 'results/scraper/launchpad-without-comments/1054180')
| -rw-r--r-- | results/scraper/launchpad-without-comments/1054180 | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/results/scraper/launchpad-without-comments/1054180 b/results/scraper/launchpad-without-comments/1054180 new file mode 100644 index 000000000..3279aa0a2 --- /dev/null +++ b/results/scraper/launchpad-without-comments/1054180 @@ -0,0 +1,16 @@ +DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu + +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. \ No newline at end of file |