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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 26 Jun 2019 07:11:41 +0100 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5Q6BUwO37028112 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Jun 2019 06:11:30 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 304F742041; Wed, 26 Jun 2019 06:11:40 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D07E94204B; Wed, 26 Jun 2019 06:11:39 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 26 Jun 2019 06:11:39 +0000 (GMT) Received: from adsilva.ozlabs.ibm.com (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id B9ADCA0283; Wed, 26 Jun 2019 16:11:38 +1000 (AEST) From: "Alastair D'Silva" To: alastair@d-silva.org Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , Pavel Tatashin , Oscar Salvador , Michal Hocko , Mike Rapoport , Baoquan He , Qian Cai , Logan Gunthorpe , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 2/3] mm: don't hide potentially null memmap pointer in sparse_remove_one_section Date: Wed, 26 Jun 2019 16:11:22 +1000 X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190626061124.16013-1-alastair@au1.ibm.com> References: <20190626061124.16013-1-alastair@au1.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19062606-0008-0000-0000-000002F7145B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19062606-0009-0000-0000-0000226447BA Message-Id: <20190626061124.16013-3-alastair@au1.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-26_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=3 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=623 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906260074 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: From: Alastair D'Silva By adding offset to memmap before passing it in to clear_hwpoisoned_pages, we hide a potentially null memmap from the null check inside clear_hwpoisoned_pages. This patch passes the offset to clear_hwpoisoned_pages instead, allowing memmap to successfully peform it's null check. Signed-off-by: Alastair D'Silva --- mm/sparse.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/sparse.c b/mm/sparse.c index 57a1a3d9c1cf..1ec32aef5590 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -753,7 +753,8 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn, #ifdef CONFIG_MEMORY_HOTREMOVE #ifdef CONFIG_MEMORY_FAILURE -static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages) +static void clear_hwpoisoned_pages(struct page *memmap, + unsigned long start, unsigned long count) { int i; @@ -769,7 +770,7 @@ static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages) if (atomic_long_read(&num_poisoned_pages) == 0) return; - for (i = 0; i < nr_pages; i++) { + for (i = start; i < start + count; i++) { if (PageHWPoison(&memmap[i])) { atomic_long_sub(1, &num_poisoned_pages); ClearPageHWPoison(&memmap[i]); @@ -777,7 +778,8 @@ static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages) } } #else -static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages) +static inline void clear_hwpoisoned_pages(struct page *memmap, + unsigned long start, unsigned long count) { } #endif @@ -824,7 +826,7 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms, ms->pageblock_flags = NULL; } - clear_hwpoisoned_pages(memmap + map_offset, + clear_hwpoisoned_pages(memmap, map_offset, PAGES_PER_SECTION - map_offset); free_section_usemap(memmap, usemap, altmap); } -- 2.21.0