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 2207AC6FA83 for ; Fri, 2 Sep 2022 19:17:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230244AbiIBTRV (ORCPT ); Fri, 2 Sep 2022 15:17:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56338 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230242AbiIBTRQ (ORCPT ); Fri, 2 Sep 2022 15:17:16 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BBABF32C9; Fri, 2 Sep 2022 12:17:15 -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 ams.source.kernel.org (Postfix) with ESMTPS id EF7CBB82D6E; Fri, 2 Sep 2022 19:17:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99C88C43144; Fri, 2 Sep 2022 19:17:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1662146232; bh=4yl99sRPWmrUl6KsCGJ2NVYDBi+JRyRa0pafSkClRQo=; h=Date:To:From:Subject:From; b=oXl5HI7n66waP0rOMqoDPGZ80PLmV8Lh5bU8LO/43v/V1RuYlaq5DRDBtGKcFAFE2 B5pfCmGTxhB/v8DPEUeNobAiySm6zMbuaO0jKIp0JFXDojKt1kYNNDl9QE680Fkyzk X/iQcX0Vz5e5Moe5sCi6nKcyL6k4qeMyedn58jrc= Date: Fri, 02 Sep 2022 12:17:11 -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: + mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch added to mm-hotfixes-unstable branch Message-Id: <20220902191712.99C88C43144@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm/migrate_device.c: copy pte dirty bit to page has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ 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-migrate_devicec-flush-tlb-while-holding-ptl.patch mm-migrate_devicec-add-missing-flush_cache_page.patch mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch 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