Message-ID: <4A43F60D.2040801@redhat.com>
Date: Thu, 25 Jun 2009 17:11:25 -0500
From: Eric Sandeen <sandeen@redhat.com>
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To: Theodore Tso <tytso@mit.edu>, Andreas Dilger <adilger@sun.com>,
       David Rientjes <rientjes@google.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>, penberg@cs.helsinki.fi,
       arjan@infradead.org, linux-kernel@vger.kernel.org,
       cl@linux-foundation.org, npiggin@suse.de, linux-ext4@vger.kernel.org
Subject: Re: upcoming kerneloops.org item: get_page_from_freelist
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Theodore Tso wrote:
> On Thu, Jun 25, 2009 at 11:26:28PM +0200, Andreas Dilger wrote:
>> IIRC there was also a good reason for this in the past, related to
>> the buffers being submitted to the block device layer, and if they
>> were allocated from the slab cache with CONFIG_DEBUG_SLAB or something
>> similar enabled the buffer would be misaligned and cause grief.
> 
> So what does SLAB/SLUB/SLOB do if we create a slab cache which is a
> power of two?  Can one of the allocators still return misaligned
> blocks of memory in some circumstances?
> 
> 						- Ted

ecryptfs used to do kmalloc(PAGE_CACHE_SIZE) & virt_to_page on that, and
with SLUB + slub debug, that gave back non-aligned memory, causing
eventual corruption ...

-Eric

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