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Date: Fri, 11 Feb 2011 09:02:45 +0200 From: Pekka Enberg <penberg@...nel.org> To: Christoph Lameter <cl@...ux.com> Cc: Russell King <rmk@....linux.org.uk>, Shiyong Li <shi-yong.li@...orola.com>, Linux Kernel List <linux-kernel@...r.kernel.org>, David Rientjes <rientjes@...gle.com> Subject: Re: "slab: Fix missing DEBUG_SLAB last user" breaks ARM On Tue, Feb 8, 2011 at 5:02 PM, Christoph Lameter <cl@...ux.com> wrote: > On Tue, 8 Feb 2011, Russell King wrote: > >> > I thought the fix was for ARM, actually, but unfortunately the >> > changelog is somewhat terse (shame on me). Hmm? >> >> As you say, the changelog is soo terse that we now have no idea why this >> commit was created. >> >> So, what's the fix here? It looks to me like a revert is in order. >> >> I suggest that if it does get reverted, a copy of my original bug report >> is included in the revert commit so that all the details are available if >> it needs revisiting. > > Uhh.. That first hunk in commit 5c5e3b33b7cb959a401f823707bee006caadd76e > looks wrong to me. ralign is usually a power of two and greater than > alignof(unsigned long long). The & operation will result in 0 and never > exempt any caches. > > diff --git a/mm/slab.c b/mm/slab.c > index bac0f4f..525c664 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -2220,8 +2220,8 @@ kmem_cache_create (const char *name, size_t size, > size_t align, > if (ralign < align) { > ralign = align; > } > - /* disable debug if necessary */ > - if (ralign > __alignof__(unsigned long long)) > + /* disable debug if not aligning with REDZONE_ALIGN */ > + if (ralign & (__alignof__(unsigned long long) - 1)) > flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER); > /* > * 4) Store it. > > > Did you mean > > if (ralign > REDZONE_ALIGN) ... > > ? Ping. Any arm-capable tester out there that can verify this fix? OTOH, since Shiyong Li hasn't showed up, I'm inclined to just revert the commit... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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