Re: [xfs-masters] Re: 2.6.22-rc1-mm1

[David Chinner <dgc@sgi.com>]

On Thu, May 17, 2007 at 10:05:11PM +0200, Michal Piotrowski wrote:
> I applied your patch and I get another oops
> 
> [  261.491499] XFS mounting filesystem loop0
> [  261.501641] Ending clean XFS mount for filesystem: loop0
> [  261.507698] SELinux: initialized (dev loop0, type xfs), uses xattr
> [  261.567441] XFS mounting filesystem loop0
> [  261.573931] allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.
> [  261.582935] xfs_buf_get_noaddr: failed to map pages
> [  261.592478] Ending clean XFS mount for filesystem: loop0
> [  261.618543] SELinux: initialized (dev loop0, type xfs), uses xattr
> [  261.691563] XFS mounting filesystem loop0
> [  261.698927] allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.
>                                   ^^^^^^^^^^^^^^^^^^^^
>                                   interesting

Yeah, looks like a vmalloc leak is occurring. I haven't noticed
it before because:

VmallocTotal: 137427898368 kB
VmallocUsed:   3128272 kB
VmallocChunk: 137424770048 kB

It takes a long time to leak enough vmapped space to run out on ia64...

That tends to imply we have a mapped buffer being leaked somewhere.
Interestingly, I don't see a memory leak so we must be freeing the
memory associated with the buffer, just not unmapping it first. Not
sure how that can happen yet.....

mount xfsVmallocUsed:    177808 kB
unmount xfs
mount xfsVmallocUsed:    178080 kB
unmount xfs
mount xfsVmallocUsed:    178352 kB
unmount xfs
mount xfsVmallocUsed:    178624 kB
unmount xfs
mount xfsVmallocUsed:    178896 kB
unmount xfs
mount xfsVmallocUsed:    179168 kB
unmount xfs
mount xfsVmallocUsed:    179440 kB
unmount xfs
mount xfsVmallocUsed:    179712 kB
unmount xfs
mount xfsVmallocUsed:    179984 kB

Looks like we're leaking 272kB of vmalloc space on each mount/unmount
cycle. I'm trying to track this down now....

> [  265.856480] Ending clean XFS mount for filesystem: loop0
> [  265.862260] SELinux: initialized (dev loop0, type xfs), uses xattr
> [  265.921288] XFS mounting filesystem loop0
> [  265.927123] xfs_buf_get_noaddr: failed to map pages
> [  265.932575] BUG: unable to handle kernel NULL pointer dereference at virtual address 00000000
....
> [  266.077866] Call Trace:
> [  266.080611]  [<fdc75a12>] xlog_alloc_log+0x1b9/0x2cd [xfs]
> [  266.086286]  [<fdc75cd1>] xfs_log_mount+0x6b/0xf1 [xfs]
> [  266.091688]  [<fdc7ec47>] xfs_mountfs+0x959/0xc4a [xfs]

Groan - ASSERT(0) is the error handling there for debug kernels. If we fail
to allocate an iclogbuf on a non-debug kernel, it will panic like this.

I'll deal with that later....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group