Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756641AbaJ1FpD (ORCPT ); Tue, 28 Oct 2014 01:45:03 -0400 Received: from relay.parallels.com ([195.214.232.42]:50649 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751985AbaJ1Fo7 (ORCPT ); Tue, 28 Oct 2014 01:44:59 -0400 Message-ID: <1414475091.8574.6.camel@tkhai> Subject: Re: [PATCH 2/3] introduce probe_slab_address() From: Kirill Tkhai To: Oleg Nesterov CC: Peter Zijlstra , , Ingo Molnar , Vladimir Davydov , Kirill Tkhai , Christoph Lameter Date: Tue, 28 Oct 2014 08:44:51 +0300 In-Reply-To: <20141027195425.GC11736@redhat.com> References: <1413962231.19914.130.camel@tkhai> <20141027195339.GA11736@redhat.com> <20141027195425.GC11736@redhat.com> Organization: Parallels Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.5-2+b3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Originating-IP: [10.30.26.172] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет: > Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe() > into the new generic helper, probe_slab_address(). The next patch will add > another user. > > Signed-off-by: Oleg Nesterov > --- > include/linux/uaccess.h | 15 +++++++++++++++ > mm/slub.c | 6 +----- > 2 files changed, 16 insertions(+), 5 deletions(-) > > diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h > index effb637..3367396 100644 > --- a/include/linux/uaccess.h > +++ b/include/linux/uaccess.h > @@ -71,6 +71,21 @@ static inline unsigned long __copy_from_user_nocache(void *to, > __probe_kernel_read(&(retval), (__force void *)(addr), sizeof(retval)) > > /* > + * Same as probe_kernel_address(), but @addr must be the valid pointer > + * to a slab object, potentially freed/reused/unmapped. > + */ > +#ifdef CONFIG_DEBUG_PAGEALLOC > +#define probe_slab_address(addr, retval) \ > + probe_kernel_address(addr, retval) > +#else > +#define probe_slab_address(addr, retval) \ > + ({ \ > + (retval) = *(typeof(retval) *)(addr); \ > + 0; \ > + }) > +#endif > + > +/* > * probe_kernel_read(): safely attempt to read from a location > * @dst: pointer to the buffer that shall take the data > * @src: address to read from > diff --git a/mm/slub.c b/mm/slub.c > index 3e8afcc..0467d22 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -265,11 +265,7 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) > { > void *p; > > -#ifdef CONFIG_DEBUG_PAGEALLOC > - probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p)); > -#else > - p = get_freepointer(s, object); > -#endif > + probe_slab_address(object + s->offset, p); > return p; > } > probe_kernel_read() was arch-dependent on tree platforms: arch/blackfin/mm/maccess.c arch/parisc/lib/memcpy.c arch/um/kernel/maccess.c But now we skip these arch-dependent implementations. Is there no a problem? Kirill -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/