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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 878A3C433EF for ; Fri, 25 Mar 2022 01:33:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357365AbiCYBfF (ORCPT ); Thu, 24 Mar 2022 21:35:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353542AbiCYBdx (ORCPT ); Thu, 24 Mar 2022 21:33:53 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB515BF01E for ; Thu, 24 Mar 2022 18:32:20 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6FF1560A50 for ; Fri, 25 Mar 2022 01:32:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C568EC340ED; Fri, 25 Mar 2022 01:32:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1648171939; bh=j6pNTE90JWRWH/A6A5RIjLRX/LexmJ4Oxm01JPltVtk=; h=Date:To:From:Subject:From; b=Ul8Pttz++oxqNz0PyMkdIA7y7roJOpzs4aJdxWnZCfrKlDulWX0Ivzg+AP3oWq//W a6PdSuJXMlqlAfV5M6tQwoJp39eaIkdGgVQb39QVuWdeX1cPgrOUvxKbEU7EyVqs7l cZkR/OZoLULPOSZA0oSWCRfSl5jbQXtqxEqo21rA= Date: Thu, 24 Mar 2022 18:32:19 -0700 To: mm-commits@vger.kernel.org, ziy@nvidia.com, shy828301@gmail.com, rcampbell@nvidia.com, kirill.shutemov@linux.intel.com, hughd@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged] mm-thp-refix-__split_huge_pmd_locked-for-migration-pmd.patch removed from -mm tree Message-Id: <20220325013219.C568EC340ED@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/thp: refix __split_huge_pmd_locked() for migration PMD has been removed from the -mm tree. Its filename was mm-thp-refix-__split_huge_pmd_locked-for-migration-pmd.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Hugh Dickins Subject: mm/thp: refix __split_huge_pmd_locked() for migration PMD Migration entries do not contribute to a page's reference count: move __split_huge_pmd_locked()'s page_ref_add() into pmd_migration's else block (along with the page_count() check - a page is quite likely to have reference count frozen to 0 when a migration entry is found). This will fix a very rare anonymous memory leak, after a split_huge_pmd() raced with an anon split_huge_page() or an anon THP migrate_pages(): since the wrongly raised refcount stopped the page (perhaps small, perhaps huge, depending on when the race hit) from ever being freed. At first I thought there were worse risks, from prematurely unfreezing a frozen page: but now think that would only affect page cache pages, which do not come this way (except for anonymous pages in swap cache, perhaps). Link: https://lkml.kernel.org/r/84792468-f512-e48f-378c-e34c3641e97@google.com Fixes: ec0abae6dcdf ("mm/thp: fix __split_huge_pmd_locked() for migration PMD") Signed-off-by: Hugh Dickins Reviewed-by: Yang Shi Cc: Ralph Campbell Cc: Zi Yan Cc: "Kirill A. Shutemov" Signed-off-by: Andrew Morton --- mm/huge_memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/huge_memory.c~mm-thp-refix-__split_huge_pmd_locked-for-migration-pmd +++ a/mm/huge_memory.c @@ -2055,9 +2055,9 @@ static void __split_huge_pmd_locked(stru young = pmd_young(old_pmd); soft_dirty = pmd_soft_dirty(old_pmd); uffd_wp = pmd_uffd_wp(old_pmd); + VM_BUG_ON_PAGE(!page_count(page), page); + page_ref_add(page, HPAGE_PMD_NR - 1); } - VM_BUG_ON_PAGE(!page_count(page), page); - page_ref_add(page, HPAGE_PMD_NR - 1); /* * Withdraw the table only after we mark the pmd entry invalid. _ Patches currently in -mm which might be from hughd@google.com are mm-delete-__clearpagewaiters.patch mm-filemap_unaccount_folio-large-skip-mapcount-fixup.patch mm-thp-fix-nr_file_mapped-accounting-in-page__file_rmap.patch mm-warn-on-deleting-redirtied-only-if-accounted.patch mm-unmap_mapping_range_tree-with-i_mmap_rwsem-shared.patch