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[156.151.31.85]) by mx.google.com with ESMTPS id l35-v6si7830699qvg.30.2018.07.02.11.05.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Jul 2018 11:05:46 -0700 (PDT) Received-SPF: pass (google.com: domain of pasha.tatashin@oracle.com designates 156.151.31.85 as permitted sender) client-ip=156.151.31.85; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2017-10-26 header.b=MZ59kktU; spf=pass (google.com: domain of pasha.tatashin@oracle.com designates 156.151.31.85 as permitted sender) smtp.mailfrom=pasha.tatashin@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w62I47gt179602; Mon, 2 Jul 2018 18:05:42 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : subject : date : message-id; s=corp-2017-10-26; bh=C6zE+J8vXI4FLk3e+K2be6GDmydsnKSY9uTRPUSkTVg=; b=MZ59kktUtxQ5g94Ni3iRD/YsyfOQBLIV3nA5v9BWR66AOt42Lx2n/Hdbt638CtTVjSs1 YWV5dNTN8OmkEUOxXpnsqsJtY9AmvGvSksdcHMl7m8Esimpz0DFPZiu91fjXWvIsrblv mAXsf6/Q4c7Cpwkg5QEHOdmAkj1VR74CkErLVgek5AGe4LYR0SH8RVidDNiLT8JUBN6C tPzhaaH7o4V5TFyWjTVZVkGI9NDLoBzhSGSOwjmM5NOLjVBNTS39ofG1azlS+qnaadLS NWvDEKrw9h976po3/UxQeqw8ThEvpScLiWqtGdbKGQBTkEwi9BvaBFMK9DYgauoplTle Mw== Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by userp2120.oracle.com with ESMTP id 2jx2gpwga6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 02 Jul 2018 18:05:42 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w62I5fFl029014 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 2 Jul 2018 18:05:41 GMT Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w62I5edp003462; Mon, 2 Jul 2018 18:05:40 GMT Received: from localhost.localdomain (/73.69.118.222) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 02 Jul 2018 11:05:40 -0700 From: Pavel Tatashin To: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, mhocko@suse.com, linux-mm@kvack.org, mgorman@techsingularity.net, gregkh@linuxfoundation.org, pasha.tatashin@oracle.com Subject: [PATCH v2] mm: teach dump_page() to correctly output poisoned struct pages Date: Mon, 2 Jul 2018 14:05:36 -0400 Message-Id: <20180702180536.2552-1-pasha.tatashin@oracle.com> X-Mailer: git-send-email 2.18.0 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8942 signatures=668704 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1807020202 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: X-Virus-Scanned: ClamAV using ClamSMTP If struct page is poisoned, and uninitialized access is detected via PF_POISONED_CHECK(page) dump_page() is called to output the page. But, the dump_page() itself accesses struct page to determine how to print it, and therefore gets into a recursive loop. For example: dump_page() __dump_page() PageSlab(page) PF_POISONED_CHECK(page) VM_BUG_ON_PGFLAGS(PagePoisoned(page), page) dump_page() recursion loop. Fixes: f165b378bbdf ("mm: uninitialized struct page poisoning sanity checking") Signed-off-by: Pavel Tatashin Acked-by: Michal Hocko --- mm/debug.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/mm/debug.c b/mm/debug.c index 56e2d9125ea5..38c926520c97 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -43,12 +43,25 @@ const struct trace_print_flags vmaflag_names[] = { void __dump_page(struct page *page, const char *reason) { + bool page_poisoned = PagePoisoned(page); + int mapcount; + + /* + * If struct page is poisoned don't access Page*() functions as that + * leads to recursive loop. Page*() check for poisoned pages, and calls + * dump_page() when detected. + */ + if (page_poisoned) { + pr_emerg("page:%px is uninitialized and poisoned", page); + goto hex_only; + } + /* * Avoid VM_BUG_ON() in page_mapcount(). * page->_mapcount space in struct page is used by sl[aou]b pages to * encode own info. */ - int mapcount = PageSlab(page) ? 0 : page_mapcount(page); + mapcount = PageSlab(page) ? 0 : page_mapcount(page); pr_emerg("page:%px count:%d mapcount:%d mapping:%px index:%#lx", page, page_ref_count(page), mapcount, @@ -60,6 +73,7 @@ void __dump_page(struct page *page, const char *reason) pr_emerg("flags: %#lx(%pGp)\n", page->flags, &page->flags); +hex_only: print_hex_dump(KERN_ALERT, "raw: ", DUMP_PREFIX_NONE, 32, sizeof(unsigned long), page, sizeof(struct page), false); @@ -68,7 +82,7 @@ void __dump_page(struct page *page, const char *reason) pr_alert("page dumped because: %s\n", reason); #ifdef CONFIG_MEMCG - if (page->mem_cgroup) + if (!page_poisoned && page->mem_cgroup) pr_alert("page->mem_cgroup:%px\n", page->mem_cgroup); #endif }