On Fri, Jun 26, 2009 at 11:58:01AM +0300, Pekka Enberg wrote: > On Fri, 2009-06-26 at 10:56 +0200, Nick Piggin wrote: > > On Fri, Jun 26, 2009 at 08:16:18AM +0300, Pekka Enberg wrote: > > > Hi Ted, > > > > > > On Thu, Jun 25, 2009 at 05:11:25PM -0500, Eric Sandeen wrote: > > > > > 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 ... > > > > > > On Thu, 25 Jun 2009, Theodore Tso wrote: > > > > Grumble. Any chance we could add an kmem_cache option which requires > > > > the memory to be aligned? Otherwise we could rewrite our own sub-page > > > > allocator in ext4 that only handled aligned filesystem block sizes > > > > (i.e., 1k, 2k, 4k, etc.) but that would be really silly and be extra > > > > code that really should be done once at core functionality. > > > > > > We alredy have SLAB_HW_ALIGN but I wonder if this is a plain old bug in > > > SLUB. Christoph, Nick, don't we need something like this in the allocator? > > > Eric, does this fix your case? > > > > Well I don't understand Ted's complaint. kmem_cache_create takes an > > alignment argument. > > Yes, but AFAICT, SLUB_DEBUG doesn't respect the given alignment without > my patch. Well your patch doesn't hurt (doesn't seem to make much sense to use objsize rather than size when calculating alignment). But I think alignment should still be calculated OK: calculate_alignemnt will always return >= align, and so the next statement will round up size to the correct alignment AFAICT. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
