Messages in this thread | | | Date | Fri, 17 Aug 2012 09:15:58 -0400 | From | Theodore Ts'o <> | Subject | Re: NULL pointer dereference in ext4_ext_remove_space on 3.5.1 |
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Thanks Fengguang:
For the record, I was able to find my own easy repro, last night using only a 220 meg partition:
# mke2fs -t ext4 -b 1024 -J size=1 /dev/vdc # mount -t ext2 /dev/vdc /vdc # mkdir /vdc/a # cd /vdc/a # seq 1 210000 | xargs -n 1 fallocate -l 1m # seq 1 2 210000 | xargs /bin/rm # mkdir /vdc/b # cd /vdc/b # seq 1 103 | xargs -n 1 fallocate -l 1g # cd / # umount /vdc # mount -t ext4 -o commit=10000 /dev/vdc /vdc # rm -rf /vdc/b
For future reference, there are a couple of things that are of interest to ext4 developers when trying to create repro's:
1) The use of mounting with ext2 to speed up the setup.
2) The first two "seq ... | xargs ..." commands to create a very fragmented file system.
3) Using a 1k block size file system to stress the extent tree code and htree directory (since its easier to make larger tree structure).
4) The use of the mount option commit=10000 to test what happens when the journal is full (without using a nice, fast device such as RAID array or without burning write cycles on an expensive flash device.)
- Ted
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