Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757538AbZJBKFR (ORCPT ); Fri, 2 Oct 2009 06:05:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757503AbZJBKFQ (ORCPT ); Fri, 2 Oct 2009 06:05:16 -0400 Received: from smtp-out.google.com ([216.239.33.17]:53846 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756831AbZJBKFO (ORCPT ); Fri, 2 Oct 2009 06:05:14 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=bBrA8mqM1mTF3pvEmaAVYMLl9hysOJmCHRMUyhC2qANVflSCINoU4UnS2Q0hWTSFW UaLl+t7TZrbue3He0eYOQ== Date: Fri, 2 Oct 2009 03:05:07 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Neil Brown cc: Suresh Jayaraman , Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, Miklos Szeredi , Wouter Verhelst , Peter Zijlstra , trond.myklebust@fys.uio.no Subject: Re: [PATCH 30/31] Fix use of uninitialized variable in cache_grow() In-Reply-To: <19141.34685.863491.329836@notabene.brown> Message-ID: References: <1254406257-16735-1-git-send-email-sjayaraman@suse.de> <19141.34685.863491.329836@notabene.brown> User-Agent: Alpine 1.00 (DEB 882 2007-12-20) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1823 Lines: 50 On Fri, 2 Oct 2009, Neil Brown wrote: > > > Index: mmotm/mm/slab.c > > > =================================================================== > > > --- mmotm.orig/mm/slab.c > > > +++ mmotm/mm/slab.c > > > @@ -2760,7 +2760,7 @@ static int cache_grow(struct kmem_cache > > > size_t offset; > > > gfp_t local_flags; > > > struct kmem_list3 *l3; > > > - int reserve; > > > + int reserve = -1; > > > > > > /* > > > * Be lazy and only check for valid flags here, keeping it out of the > > > @@ -2816,7 +2816,8 @@ static int cache_grow(struct kmem_cache > > > if (local_flags & __GFP_WAIT) > > > local_irq_disable(); > > > check_irq_off(); > > > - slab_set_reserve(cachep, reserve); > > > + if (reserve != -1) > > > + slab_set_reserve(cachep, reserve); > > > spin_lock(&l3->list_lock); > > > > > > /* Make slab active. */ > > > > Given the patch description, shouldn't this be a test for objp != NULL > > instead, then? > > In between those to patch hunks, cache_grow contains the code: > if (!objp) > objp = kmem_getpages(cachep, local_flags, nodeid, &reserve); > if (!objp) > goto failed; > > We can no longer test if objp was NULL on entry to the function. > We could take a copy of objp on entry to the function, and test it > here. But initialising 'reserve' to an invalid value is easier. > Seems like you could do all this in kmem_getpages(), then, by calling slab_set_reserve(cachep, page->reserve) before returning the new page? [ I'd also drop the branch in slab_set_reserve(), it's faster to just assign it unconditionally. ] -- 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/