On Fri, Jul 18, 2008 at 05:30:24PM +0530, Aneesh Kumar K.V wrote:

On Tue, Jul 15, 2008 at 02:06:21PM +1000, Shehjar Tikoo wrote:

quoted

Hi all

I've observed the following kernel crash during tests against ext4  
fallocate'ion support on 2.6.26.

Stack trace is at:
http://www.gelato.unsw.edu.au/~shehjart/docs/ext4_fallocate_test_trace_2.6.26.txt

The test involved running the following program which fallocates a given 
length in bytes then writes to it. The above crash was seen when writing 
to an ext4 disk, 2G file, in blocks of 64k with fallocate requests of 
1mb. After each 1mb of data is written to the fallocated space, another 
1mb is requested. This write-fallocate cycle continues till the requested 
file size is reached. The trace is from one of the crashes from the 
various runs(all crashed). I must emphasise that after one of the runs, 
the test disk could not be mounted as the filesystem was unrecognized. 
ext4dev was mounted in data=ordered mode.

See the test code at:
http://www.gelato.unsw.edu.au/~shehjart/docs/writefallocate.c

The command line arguments are self-explanatory. Run without any  
arguments to see the usage message. Do change the _NR_fallocate define  
at the beginning of the file to your architecture's syscall number for  
sys_fallocate.

I can run a few more tests if more info is needed.

Can you try this patch ?

I tested this on powerpc and x86 where i was able to reproduce the
problem earlier. With the fix the test runs fine.

-aneesh