From patchwork Mon Dec 23 02:24:35 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Yang X-Patchwork-Id: 11307741 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AB51E13B6 for ; Mon, 23 Dec 2019 02:24:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 788B820409 for ; Mon, 23 Dec 2019 02:24:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 788B820409 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4C5F58E0005; Sun, 22 Dec 2019 21:24:48 -0500 (EST) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 475688E0001; Sun, 22 Dec 2019 21:24:48 -0500 (EST) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3D9FD8E0005; Sun, 22 Dec 2019 21:24:48 -0500 (EST) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0162.hostedemail.com [216.40.44.162]) by kanga.kvack.org (Postfix) with ESMTP id 2B92E8E0001 for ; Sun, 22 Dec 2019 21:24:48 -0500 (EST) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id C6B4E8249980 for ; Mon, 23 Dec 2019 02:24:47 +0000 (UTC) X-FDA: 76294813014.08.ghost16_8113b863fad3c X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,richardw.yang@linux.intel.com,:akpm@linux-foundation.org::linux-kernel@vger.kernel.org:kirill.shutemov@linux.intel.com:richardw.yang@linux.intel.com,RULES_HIT:30003:30054:30070,0,RBL:134.134.136.31:@linux.intel.com:.lbl8.mailshell.net-62.18.0.100 64.95.201.95,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:23,LUA_SUMMARY:none X-HE-Tag: ghost16_8113b863fad3c X-Filterd-Recvd-Size: 2628 Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Mon, 23 Dec 2019 02:24:46 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Dec 2019 18:24:45 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,346,1571727600"; d="scan'208";a="211403168" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by orsmga008.jf.intel.com with ESMTP; 22 Dec 2019 18:24:43 -0800 From: Wei Yang To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kirill.shutemov@linux.intel.com, Wei Yang Subject: [PATCH] mm/rmap.c: split huge pmd when it really is Date: Mon, 23 Dec 2019 10:24:35 +0800 Message-Id: <20191223022435.30653-1-richardw.yang@linux.intel.com> X-Mailer: git-send-email 2.17.1 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000072, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: There are two cases to call try_to_unmap_one() with TTU_SPLIT_HUGE_PMD set: * unmap_page() * shrink_page_list() In both case, the page passed to try_to_unmap_one() is PageHead() of the THP. If this page's mapping address in process is not HPAGE_PMD_SIZE aligned, this means the THP is not mapped as PMD THP in this process. This could happen when we do mremap() a PMD size range to an un-aligned address. Currently, this case is handled by following check in __split_huge_pmd() luckily. page != pmd_page(*pmd) This patch checks the address to skip some hard work. Signed-off-by: Wei Yang Reported-by: kbuild test robot --- mm/rmap.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/mm/rmap.c b/mm/rmap.c index b3e381919835..79b9239f00e3 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1386,7 +1386,19 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, is_zone_device_page(page) && !is_device_private_page(page)) return true; - if (flags & TTU_SPLIT_HUGE_PMD) { + /* + * There are two places set TTU_SPLIT_HUGE_PMD + * + * unmap_page() + * shrink_page_list() + * + * In both cases, the "page" here is the PageHead() of the THP. + * + * If the page is not a real PMD huge page, e.g. after mremap(), it is + * not necessary to split. + */ + if ((flags & TTU_SPLIT_HUGE_PMD) && + IS_ALIGNED(address, HPAGE_PMD_SIZE)) { split_huge_pmd_address(vma, address, flags & TTU_SPLIT_FREEZE, page); }