From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EBADC433DF for ; Tue, 13 Oct 2020 23:56:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DD2FF2222E for ; Tue, 13 Oct 2020 23:56:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="yeNs/z7v" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DD2FF2222E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8484E6B0136; Tue, 13 Oct 2020 19:56:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 81DD86B0137; Tue, 13 Oct 2020 19:56:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 75B4B6B0138; Tue, 13 Oct 2020 19:56:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0186.hostedemail.com [216.40.44.186]) by kanga.kvack.org (Postfix) with ESMTP id 47F586B0136 for ; Tue, 13 Oct 2020 19:56:03 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id D70AE180AD807 for ; Tue, 13 Oct 2020 23:56:02 +0000 (UTC) X-FDA: 77368562964.20.drain79_2e08a0e27207 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id B3B6F180C07AB for ; Tue, 13 Oct 2020 23:56:02 +0000 (UTC) X-HE-Tag: drain79_2e08a0e27207 X-Filterd-Recvd-Size: 3159 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Tue, 13 Oct 2020 23:56:02 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 311082222F; Tue, 13 Oct 2020 23:56:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602633361; bh=V8afr/ISGu8bfolhVbNirbweRZXldyRBGEBPEl5Gnh8=; h=Date:From:To:Subject:In-Reply-To:From; b=yeNs/z7vmwEriocEBEZJdKik9CP/MkDiG5iWZsHTMjh7F6BLb0hMPewZgzBUOJwfO p5IpW5PYe485XTCY0zLt10uOc0Oqgk8Tp21pkrAt8cKr/AGk/3e3VNPm/bAoP7OAs8 vUWny5RFwSZZBSJpZu9GyakvEb6LcJTRAAsRuWM4= Date: Tue, 13 Oct 2020 16:56:00 -0700 From: Andrew Morton To: akpm@linux-foundation.org, dan.j.williams@intel.com, hch@lst.de, linux-mm@kvack.org, mm-commits@vger.kernel.org, rcampbell@nvidia.com, torvalds@linux-foundation.org, willy@infradead.org, yuzhao@google.com Subject: [patch 138/181] mm: move call to compound_head() in release_pages() Message-ID: <20201013235600.qVPy8ZgOD%akpm@linux-foundation.org> In-Reply-To: <20201013164658.3bfd96cc224d8923e66a9f4e@linux-foundation.org> User-Agent: s-nail v14.8.16 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: Ralph Campbell Subject: mm: move call to compound_head() in release_pages() The function is_huge_zero_page() doesn't call compound_head() to make sure the page pointer is a head page. The call to is_huge_zero_page() in release_pages() is made before compound_head() is called so the test would fail if release_pages() was called with a tail page of the huge_zero_page and put_page_testzero() would be called releasing the page. This is unlikely to be happening in normal use or we would be seeing all sorts of process data corruption when accessing a THP zero page. Looking at other places where is_huge_zero_page() is called, all seem to only pass a head page so I think the right solution is to move the call to compound_head() in release_pages() to a point before calling is_huge_zero_page(). Link: https://lkml.kernel.org/r/20200917173938.16420-1-rcampbell@nvidia.com Signed-off-by: Ralph Campbell Reviewed-by: Andrew Morton Cc: Yu Zhao Cc: Dan Williams Cc: Matthew Wilcox Cc: Christoph Hellwig Signed-off-by: Andrew Morton --- mm/swap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/swap.c~mm-move-call-to-compound_head-in-release_pages +++ a/mm/swap.c @@ -889,6 +889,7 @@ void release_pages(struct page **pages, locked_pgdat = NULL; } + page = compound_head(page); if (is_huge_zero_page(page)) continue; @@ -910,7 +911,6 @@ void release_pages(struct page **pages, } } - page = compound_head(page); if (!put_page_testzero(page)) continue; _