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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 17 Jun 2019 05:38:02 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5H4c1mv37093562 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Jun 2019 04:38:01 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6CEAC11C058; Mon, 17 Jun 2019 04:38:01 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 14A0211C050; Mon, 17 Jun 2019 04:38:01 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 17 Jun 2019 04:38:01 +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 01A97A0208; Mon, 17 Jun 2019 14:38:00 +1000 (AEST) From: "Alastair D'Silva" To: alastair@d-silva.org Cc: Andrew Morton , Oscar Salvador , David Hildenbrand , Michal Hocko , Pavel Tatashin , Wei Yang , Juergen Gross , Qian Cai , Thomas Gleixner , Ingo Molnar , Josh Poimboeuf , Konrad Rzeszutek Wilk , Jiri Kosina , Peter Zijlstra , Mukesh Ojha , Arun KS , Mike Rapoport , Baoquan He , Logan Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/5] mm: don't hide potentially null memmap pointer in sparse_remove_one_section Date: Mon, 17 Jun 2019 14:36:28 +1000 X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190617043635.13201-1-alastair@au1.ibm.com> References: <20190617043635.13201-1-alastair@au1.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19061704-0020-0000-0000-0000034AAC29 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19061704-0021-0000-0000-0000219DEF16 Message-Id: <20190617043635.13201-3-alastair@au1.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-17_03:,, 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=544 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906170042 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, is hides 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 | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/mm/sparse.c b/mm/sparse.c index 104a79fedd00..66a99da9b11b 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -746,12 +746,14 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn, kfree(usemap); __kfree_section_memmap(memmap, altmap); } + return ret; } #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 map_offset, int nr_pages) { int i; @@ -767,7 +769,7 @@ 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 = map_offset; i < nr_pages; i++) { if (PageHWPoison(&memmap[i])) { atomic_long_sub(1, &num_poisoned_pages); ClearPageHWPoison(&memmap[i]); @@ -775,7 +777,8 @@ 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 map_offset, int nr_pages) { } #endif @@ -822,8 +825,7 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms, ms->pageblock_flags = NULL; } - clear_hwpoisoned_pages(memmap + map_offset, - PAGES_PER_SECTION - map_offset); + clear_hwpoisoned_pages(memmap, map_offset, PAGES_PER_SECTION); free_section_usemap(memmap, usemap, altmap); } #endif /* CONFIG_MEMORY_HOTREMOVE */ -- 2.21.0