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Fri, 14 Aug 2020 06:58:00 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 07E6vVmv139079; Fri, 14 Aug 2020 06:57:55 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3020.oracle.com with ESMTP id 32t5ybtv6d-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 14 Aug 2020 06:57:54 +0000 Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 07E6vqfD003773; Fri, 14 Aug 2020 06:57:53 GMT Received: from [10.159.133.241] (/10.159.133.241) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 14 Aug 2020 06:57:52 +0000 Subject: Re: [PATCH] mm: slub: fix conversion of freelist_corrupted() To: Eugeniu Rosca , Andrew Morton Cc: linux-mm@kvack.org, stable@vger.kernel.org, Eugeniu Rosca References: <20200811124656.10308-1-erosca@de.adit-jv.com> From: Dongli Zhang Message-ID: Date: Thu, 13 Aug 2020 23:57:51 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200811124656.10308-1-erosca@de.adit-jv.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9712 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 malwarescore=0 suspectscore=0 mlxscore=0 adultscore=0 bulkscore=0 phishscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008140053 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9712 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 priorityscore=1501 malwarescore=0 impostorscore=0 lowpriorityscore=0 mlxscore=0 bulkscore=0 suspectscore=0 phishscore=0 adultscore=0 spamscore=0 clxscore=1011 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008140053 X-Rspamd-Queue-Id: 0E1C780137C2 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 8/11/20 5:46 AM, Eugeniu Rosca wrote: > Commit 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in > deactivate_slab()") suffered an update when picked up from LKML [1]. > > Specifically, relocating 'freelist = NULL' into 'freelist_corrupted()' > created a no-op statement. Fix it by sticking to the behavior intended > in the original patch [1]. Prefer the lowest-line-count solution. > > [1] https://lore.kernel.org/linux-mm/20200331031450.12182-1-dongli.zhang@oracle.com/ > > Fixes: 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in deactivate_slab()") > Cc: Andrew Morton > Cc: Dongli Zhang > Cc: > Signed-off-by: Eugeniu Rosca > --- > mm/slub.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 68c02b2eecd9..9a3e963b02a3 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -677,7 +677,6 @@ static bool freelist_corrupted(struct kmem_cache *s, struct page *page, > if ((s->flags & SLAB_CONSISTENCY_CHECKS) && > !check_valid_pointer(s, page, nextfree)) { > object_err(s, page, freelist, "Freechain corrupt"); > - freelist = NULL; > slab_fix(s, "Isolate corrupted freechain"); > return true; > } > @@ -2184,8 +2183,10 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, > * 'freelist' is already corrupted. So isolate all objects > * starting at 'freelist'. > */ > - if (freelist_corrupted(s, page, freelist, nextfree)) > + if (freelist_corrupted(s, page, freelist, nextfree)) { > + freelist = NULL; This is good to me. However, this would confuse people when CONFIG_SLUB_DEBUG is not defined. While reading the source code, people may be curious why to reset freelist when CONFIG_SLUB_DEBUG is even not defined. Dongli Zhang