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[67.231.145.42]) by mx.google.com with ESMTPS id v186si35417782pgd.358.2019.08.01.11.43.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Aug 2019 11:43:03 -0700 (PDT) Received-SPF: pass (google.com: domain of prvs=3116992784=songliubraving@fb.com designates 67.231.145.42 as permitted sender) client-ip=67.231.145.42; Authentication-Results: mx.google.com; dkim=pass header.i=@fb.com header.s=facebook header.b=lpapXaVx; spf=pass (google.com: domain of prvs=3116992784=songliubraving@fb.com designates 67.231.145.42 as permitted sender) smtp.mailfrom="prvs=3116992784=songliubraving@fb.com"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=fb.com Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x71IgjR8026770 for ; Thu, 1 Aug 2019 11:43:02 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=lq7eKJkDsLmHUV4qu7iZTnjT46Y88VB+lwzmGkYti6U=; b=lpapXaVxfIKHC/ZsfavKbczUogVos6FhHhByK2rkJHhxRup9QMEqFYJsHh7DbKfuyc36 2vQssz0CJR1mpxFJ4VdxcLs884xwsE9DxoTuyHN9aqw5CzaB5pmyPJ+HQ/iMvR9ls3a/ qy7zJyo/6NAkNfntRYgboDezLa9r7q7eri8= Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2u438rgmnr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Thu, 01 Aug 2019 11:43:02 -0700 Received: from mx-out.facebook.com (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::125) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Thu, 1 Aug 2019 11:43:01 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 1961F62E1E18; Thu, 1 Aug 2019 11:43:01 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig006.ftw2.facebook.com To: , , CC: , , , , , , Song Liu Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH v10 2/7] filemap: check compound_head(page)->mapping in pagecache_get_page() Date: Thu, 1 Aug 2019 11:42:39 -0700 Message-ID: <20190801184244.3169074-3-songliubraving@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190801184244.3169074-1-songliubraving@fb.com> References: <20190801184244.3169074-1-songliubraving@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-01_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=750 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908010194 X-FB-Internal: deliver 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: Similar to previous patch, pagecache_get_page() avoids race condition with truncate by checking page->mapping == mapping. This does not work for compound pages. This patch let it check compound_head(page)->mapping instead. Suggested-by: Johannes Weiner Signed-off-by: Song Liu --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/filemap.c b/mm/filemap.c index d0bd9e585c2f..aaee1ef96f6d 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1644,7 +1644,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset, } /* Has the page been truncated? */ - if (unlikely(page->mapping != mapping)) { + if (unlikely(compound_head(page)->mapping != mapping)) { unlock_page(page); put_page(page); goto repeat; -- 2.17.1