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 56E14ECAAD3 for ; Sun, 11 Sep 2022 23:23:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229598AbiIKXXR (ORCPT ); Sun, 11 Sep 2022 19:23:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229565AbiIKXXN (ORCPT ); Sun, 11 Sep 2022 19:23:13 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F80A2655C; Sun, 11 Sep 2022 16:23:11 -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 CB0C661035; Sun, 11 Sep 2022 23:23:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A5CDC433D6; Sun, 11 Sep 2022 23:23:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1662938590; bh=au9b+SQHjNH9FxENMrkhGfd5grkei92y/Qq+VMSO4e8=; h=Date:To:From:Subject:From; b=HafiCVRhW4wEEf3hgzfa+TesublxThdJLbzH9jL3+fTmHmUP0h6+EyXNNnVHI6Reo oeKannt9CD+o+hZYn+bOIq+AevMGaqhPSE2A4zgSpyg6gB7J7Nbh8FCO7brDXpIMly uryFRI1Qnnk6Z6s2vxKVXwEztz+NUHoEHICMcl7o= Date: Sun, 11 Sep 2022 16:23:09 -0700 To: mm-commits@vger.kernel.org, ying.huang@intel.com, willy@infradead.org, stable@vger.kernel.org, rcampbell@nvidia.com, peterx@redhat.com, paulus@ozlabs.org, nadav.amit@gmail.com, lyude@redhat.com, logang@deltatee.com, kherbst@redhat.com, jhubbard@nvidia.com, jgg@nvidia.com, huang.ying.caritas@gmail.com, Felix.Kuehling@amd.com, david@redhat.com, bskeggs@redhat.com, alex.sierra@amd.com, apopple@nvidia.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch removed from -mm tree Message-Id: <20220911232310.2A5CDC433D6@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The quilt patch titled Subject: mm/migrate_device.c: copy pte dirty bit to page has been removed from the -mm tree. Its filename was mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Alistair Popple Subject: mm/migrate_device.c: copy pte dirty bit to page Date: Fri, 2 Sep 2022 10:35:53 +1000 migrate_vma_setup() has a fast path in migrate_vma_collect_pmd() that installs migration entries directly if it can lock the migrating page. When removing a dirty pte the dirty bit is supposed to be carried over to the underlying page to prevent it being lost. Currently migrate_vma_*() can only be used for private anonymous mappings. That means loss of the dirty bit usually doesn't result in data loss because these pages are typically not file-backed. However pages may be backed by swap storage which can result in data loss if an attempt is made to migrate a dirty page that doesn't yet have the PageDirty flag set. In this case migration will fail due to unexpected references but the dirty pte bit will be lost. If the page is subsequently reclaimed data won't be written back to swap storage as it is considered uptodate, resulting in data loss if the page is subsequently accessed. Prevent this by copying the dirty bit to the page when removing the pte to match what try_to_migrate_one() does. Link: https://lkml.kernel.org/r/dd48e4882ce859c295c1a77612f66d198b0403f9.1662078528.git-series.apopple@nvidia.com Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages") Signed-off-by: Alistair Popple Acked-by: Peter Xu Reviewed-by: "Huang, Ying" Reported-by: "Huang, Ying" Acked-by: David Hildenbrand Cc: Alex Sierra Cc: Ben Skeggs Cc: Felix Kuehling Cc: huang ying Cc: Jason Gunthorpe Cc: John Hubbard Cc: Karol Herbst Cc: Logan Gunthorpe Cc: Lyude Paul Cc: Matthew Wilcox Cc: Nadav Amit Cc: Paul Mackerras Cc: Ralph Campbell Cc: Signed-off-by: Andrew Morton --- mm/migrate_device.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/mm/migrate_device.c~mm-migrate_devicec-copy-pte-dirty-bit-to-page +++ a/mm/migrate_device.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include @@ -196,7 +197,7 @@ again: flush_cache_page(vma, addr, pte_pfn(*ptep)); anon_exclusive = PageAnon(page) && PageAnonExclusive(page); if (anon_exclusive) { - ptep_clear_flush(vma, addr, ptep); + pte = ptep_clear_flush(vma, addr, ptep); if (page_try_share_anon_rmap(page)) { set_pte_at(mm, addr, ptep, pte); @@ -206,11 +207,15 @@ again: goto next; } } else { - ptep_get_and_clear(mm, addr, ptep); + pte = ptep_get_and_clear(mm, addr, ptep); } migrate->cpages++; + /* Set the dirty flag on the folio now the pte is gone. */ + if (pte_dirty(pte)) + folio_mark_dirty(page_folio(page)); + /* Setup special migration page table entry */ if (mpfn & MIGRATE_PFN_WRITE) entry = make_writable_migration_entry( _ Patches currently in -mm which might be from apopple@nvidia.com are mm-gupc-simplify-and-fix-check_and_migrate_movable_pages-return-codes.patch selftests-hmm-tests-add-test-for-dirty-bits.patch mm-gupc-dont-pass-gup_flags-to-check_and_migrate_movable_pages.patch mm-gupc-refactor-check_and_migrate_movable_pages.patch mm-migrate_devicec-fix-a-misleading-and-out-dated-comment.patch