Re: ext4 fallocate related crash on 2.6.26

[Aneesh Kumar K.V]

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:
> > 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
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