Re: [BLOCK] bh: Ensure bh fits within a page

From: Andrew Morton
Date: Tue Aug 01 2006 - 01:53:02 EST

On Tue, 1 Aug 2006 15:02:59 +1000
Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:

> On Mon, Jul 31, 2006 at 09:04:18PM -0700, Andrew Morton wrote:
> >
> > Could we have a more detailed description?
> Sure, this particular instance is in journal_write_metadata_buffer
> where the bh may be constructed from kmalloc memory (search for the
> call to jbd_rep_kmalloc). Because the memory returned by kmalloc
> may straddle a page (when slab debugging is enabled that is), this
> causes a broken bh to be injected into submit_bh.

Crap, that's hard to fix. Am I allowed to blame submit_bh()? ;)

uhm, we don't want to lose kmalloc redzoning, so I guess we need to create
on-demand ext3-private slab caches for 1024, 2048, and 4096 bytes. With
the appropriate slab flags to defeat the redzoning.
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