From patchwork Thu Jul 1 01:48:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12353129 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=unavailable 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 C5B18C11F69 for ; Thu, 1 Jul 2021 01:49:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7E83461090 for ; Thu, 1 Jul 2021 01:49:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E83461090 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 076DB8D01F6; Wed, 30 Jun 2021 21:49:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 04E3E8D01D0; Wed, 30 Jun 2021 21:49:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E57378D01F6; Wed, 30 Jun 2021 21:49:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0061.hostedemail.com [216.40.44.61]) by kanga.kvack.org (Postfix) with ESMTP id BE8938D01D0 for ; Wed, 30 Jun 2021 21:49:01 -0400 (EDT) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 945C2252D7 for ; Thu, 1 Jul 2021 01:49:01 +0000 (UTC) X-FDA: 78312335682.31.D3251F1 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf11.hostedemail.com (Postfix) with ESMTP id 235DEF0000AF for ; Thu, 1 Jul 2021 01:49:00 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id A29D261469; Thu, 1 Jul 2021 01:48:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1625104140; bh=iUaA8MK1PDOj7bGi7HEjZogXJ88oDseJdbLzFpj1Kk0=; h=Date:From:To:Subject:In-Reply-To:From; b=HB0nxXAZf/Vex0k5PM5fZzrXsGpoxLS9JPLUUh9xUaG1ahydLGl+6aeHj337dusVQ Mj6rs2zdot6lrA7D8AR/6oRlN2WoixQmvcjIvid9KSKy8G35onH3D2Gnc0KDUztY2Z IJWmDHgSSw4+bbX8X+603rE8d+QtaryFaWV5sLpQ= Date: Wed, 30 Jun 2021 18:48:59 -0700 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, almasrymina@google.com, axelrasmussen@google.com, bgeffon@google.com, dgilbert@redhat.com, hughd@google.com, jglisse@redhat.com, joe@perches.com, kirill@shutemov.name, linux-mm@kvack.org, lokeshgidra@google.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, oupton@google.com, peterx@redhat.com, rppt@linux.vnet.ibm.com, sfr@canb.auug.org.au, shli@fb.com, shuah@kernel.org, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, wangqing@vivo.com Subject: [patch 035/192] mm/thp: simplify copying of huge zero page pmd when fork Message-ID: <20210701014859.DK9n7jkks%akpm@linux-foundation.org> In-Reply-To: <20210630184624.9ca1937310b0dd5ce66b30e7@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 235DEF0000AF X-Stat-Signature: r67pmde3ei38cp3kqad6g8tb4gp94d1b Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=HB0nxXAZ; dmarc=none; spf=pass (imf11.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-HE-Tag: 1625104140-812845 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: Peter Xu Subject: mm/thp: simplify copying of huge zero page pmd when fork Patch series "mm/uffd: Misc fix for uffd-wp and one more test". This series tries to fix some corner case bugs for uffd-wp on either thp or fork(). Then it introduced a new test with pagemap/pageout. Patch layout: Patch 1: cleanup for THP, it'll slightly simplify the follow up patches Patch 2-4: misc fixes for uffd-wp here and there; please refer to each patch Patch 5: add pagemap support for uffd-wp Patch 6: add pagemap/pageout test for uffd-wp The last test introduced can also verify some of the fixes in previous patches, as the test will fail without the fixes. However it's not easy to verify all the changes in patch 2-4, but hopefully they can still be properly reviewed. Note that if considering the ongoing uffd-wp shmem & hugetlbfs work, patch 5 will be incomplete as it's missing e.g. hugetlbfs part or the special swap pte detection. However that's not needed in this series, and since that series is still during review, this series does not depend on that one (the last test only runs with anonymous memory, not file-backed). So this series can be merged even before that series. This patch (of 6): Huge zero page is handled in a special path in copy_huge_pmd(), however it should share most codes with a normal thp page. Trying to share more code with it by removing the special path. The only leftover so far is the huge zero page refcounting (mm_get_huge_zero_page()), because that's separately done with a global counter. This prepares for a future patch to modify the huge pmd to be installed, so that we don't need to duplicate it explicitly into huge zero page case too. Link: https://lkml.kernel.org/r/20210428225030.9708-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210428225030.9708-2-peterx@redhat.com Signed-off-by: Peter Xu Cc: Kirill A. Shutemov Cc: Mike Kravetz , peterx@redhat.com Cc: Mike Rapoport Cc: Axel Rasmussen Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Jerome Glisse Cc: Alexander Viro Cc: Brian Geffon Cc: "Dr . David Alan Gilbert" Cc: Joe Perches Cc: Lokesh Gidra Cc: Mina Almasry Cc: Oliver Upton Cc: Shaohua Li Cc: Shuah Khan Cc: Stephen Rothwell Cc: Wang Qing Signed-off-by: Andrew Morton --- mm/huge_memory.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) --- a/mm/huge_memory.c~mm-thp-simplify-copying-of-huge-zero-page-pmd-when-fork +++ a/mm/huge_memory.c @@ -1088,17 +1088,13 @@ int copy_huge_pmd(struct mm_struct *dst_ * a page table. */ if (is_huge_zero_pmd(pmd)) { - struct page *zero_page; /* * get_huge_zero_page() will never allocate a new page here, * since we already have a zero page to copy. It just takes a * reference. */ - zero_page = mm_get_huge_zero_page(dst_mm); - set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, - zero_page); - ret = 0; - goto out_unlock; + mm_get_huge_zero_page(dst_mm); + goto out_zero_page; } src_page = pmd_page(pmd); @@ -1122,6 +1118,7 @@ int copy_huge_pmd(struct mm_struct *dst_ get_page(src_page); page_dup_rmap(src_page, true); add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); +out_zero_page: mm_inc_nr_ptes(dst_mm); pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);