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Diffstat (limited to 'results/classifier/gemma3:12b/files/1661758')
| -rw-r--r-- | results/classifier/gemma3:12b/files/1661758 | 118 |
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diff --git a/results/classifier/gemma3:12b/files/1661758 b/results/classifier/gemma3:12b/files/1661758 new file mode 100644 index 00000000..194baf3b --- /dev/null +++ b/results/classifier/gemma3:12b/files/1661758 @@ -0,0 +1,118 @@ + +qemu-nbd causes data corruption in VDI-format disk images + +Hi, + +This is a duplicate of #1422307. I can't figure out a way to re-open +it--the status of "Fix Released" is changeable only by a project +maintainer or bug supervisor--so I'm opening a new bug to make sure +this gets looked at again. + +qemu-nbd will sometimes corrupt VDI disk images. The bug was thought +to be fixed in commit f0ab6f109630940146cbaf47d0cd99993ddba824, but +I'm able to reproduce it in both that commit and in the latest commit +(a951316b8a5c3c63254f20a826afeed940dd4cba). I just needed to run more +iterations of the test. It's possible that it was partially fixed, or +that the added serialization made it harder to catch this +non-deterministic bug, but the same symptoms persist: data corruption +of VDI-format disk images. + +This affects at least qemu-nbd. I haven't tried reproducing the issue +with qemu proper or qemu-img, but the original bug report suggests +that the bug in the common VDI backend may corrupt data written by +those programs. + +Please let me know if I can provide any further information or help +with testing. Thank you very much for looking into this! + +Test procedure +************** + +The procedure used is the one given by Max Reitz (xanclic) in the +original bug report, comment 3 +(https://bugs.launchpad.net/qemu/+bug/1422307/comments/3), in the +section "VDI and NBD over /dev/nbd0", but with up to 1000 iterations +instead of 10: + + $ cd ~/qemu-origfix-f0ab6f1/bin + $ dd if=/dev/urandom of=blob.raw bs=1M count=64 + 64+0 records in + 64+0 records out + 67108864 bytes (67 MB) copied, 4.36475 s, 15.4 MB/s + $ sudo sh -c 'for i in $(seq 0 999); do ./qemu-img create -f vdi test.vdi 64M > /dev/null; ./qemu-nbd -c /dev/nbd0 test.vdi; sleep 1; ./qemu-img convert -n blob.raw /dev/nbd0; ./qemu-img convert /dev/nbd0 test1.raw; sync; echo 1 > /proc/sys/vm/drop_caches; ./qemu-img convert /dev/nbd0 test2.raw; ./qemu-nbd -d /dev/nbd0 > /dev/null; if ! ./qemu-img compare -q test1.raw test2.raw; then md5sum test1.raw test2.raw; echo "$i failed"; break; fi; done; echo "done"' +27a66c3a8ac2cf06f2c925968ea9e964 test1.raw +2da9bf169041a7c2bd144c4ab3a29aea test2.raw +64 failed +done + +I've run this process a handful of times, and I've seen it take as +little as 10 iterations and as many as 161 (taking 32 minutes in the +latter case). Please be patient. Putting the images on tmpfs will +probably help it go faster, and I have successfully reproduced the +issue on tmpfs in addition to ext4. + +Nothing different was needed to reproduce the issue in a directory +containing a build of the latest commit. It still takes somewhere +around 1-200 iterations to find, in my testing. + +Build procedure +*************** + + $ git clone git://git.qemu-project.org/qemu.git + [omitted] + $ git clone qemu qemu-origfix-f0ab6f1 + Cloning into 'qemu-origfix-f0ab6f1'... + done. + $ cd qemu-origfix-f0ab6f1 + $ git checkout f0ab6f109630940146cbaf47d0cd99993ddba824 + Note: checking out 'f0ab6f109630940146cbaf47d0cd99993ddba824'. + + You are in 'detached HEAD' state. You can look around, make experimental + changes and commit them, and you can discard any commits you make in this + state without impacting any branches by performing another checkout. + + If you want to create a new branch to retain commits you create, you may + do so (now or later) by using -b with the checkout command again. Example: + + git checkout -b new_branch_name + + HEAD is now at f0ab6f1... block/vdi: Add locking for parallel requests + $ mkdir bin + $ cd bin + $ script -c'time (../configure --enable-debug --target-list=x86_64-softmmu && make -j6; echo "result: $?")' + Script started, file is typescript + [omitted; the build typescript is attached separately] + LINK x86_64-softmmu/qemu-system-x86_64 + result: 0 + + real 1m5.733s + user 2m3.904s + sys 0m13.828s + Script done, file is typescript + +Nothing different was done when building the latest commit (besides +cloning to a different directory, and not running `git checkout`). + +Environment +*********** + + * Machine: x86_64 + + * Hypervisor: Xen 4.4 (Debian package xen-hypervisor-4.4-amd64, + version 4.4.1-9+deb8u8) + + * A Xen domU (guest) for building QEMU and reproducing the issue. + All testing was done within the virtual machine for convenience + and access to better hardware than what I have for my development + machine (I expected the build to take much longer than it really + does). + + - x86_64 architecture with six VCPUs and 1.2 GiB RAM allocated, + operating in HVM (fully virtualized) mode. + + - Distribution: Debian 8.7 Jessie amd64 + + - Kernel: Linux 3.16.0 x86_64 (Debian package + linux-image-3.16.0-4-amd64, version 3.16.39-1) + + - Compiler: GCC 4.9.2 (Debian package gcc-4.9, version 4.9.2-10) \ No newline at end of file |