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 E40DCECAAD4 for ; Sat, 27 Aug 2022 02:38:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232194AbiH0CiN (ORCPT ); Fri, 26 Aug 2022 22:38:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232193AbiH0CiN (ORCPT ); Fri, 26 Aug 2022 22:38:13 -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 1FA05DD742; Fri, 26 Aug 2022 19:38:12 -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 9D8A261D52; Sat, 27 Aug 2022 02:38:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2BAEC433C1; Sat, 27 Aug 2022 02:38:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1661567891; bh=xAh3+xuOAJg4/Wh56t+f8yWCmCtKfXQ2/fZXPFuBCbU=; h=Date:To:From:Subject:From; b=xqlyjPpAx2yDQlq3vKCnIEckt56WY52zhElp72zmCQpaDctV+NaqCA+EEDKcMbkSR 11LcveILKGnIkZXscNAVtRi20u7T0VQ82tp6fyuESCA6uYShuZxGmJEA//Ff8KN57Q Y7URzLbJly23QY9aS9FsJT2arBFpxQbNSl5DfH4M= Date: Fri, 26 Aug 2022 19:38:10 -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, lyude@redhat.com, logang@deltatee.com, kherbst@redhat.com, jhubbard@nvidia.com, jgg@nvidia.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: [to-be-updated] mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch removed from -mm tree Message-Id: <20220827023810.E2BAEC433C1@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 an updated version will be merged ------------------------------------------------------ From: Alistair Popple Subject: mm/migrate_device.c: copy pte dirty bit to page Date: Tue, 16 Aug 2022 17:39:24 +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/6e77914685ede036c419fa65b6adc27f25a6c3e9.1660635033.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 Reported-by: Huang Ying Reviewed-by: Huang Ying Cc: Alex Sierra Cc: Ben Skeggs Cc: David Hildenbrand Cc: Felix Kuehling Cc: Jason Gunthorpe Cc: John Hubbard Cc: Karol Herbst Cc: Logan Gunthorpe Cc: Lyude Paul Cc: Matthew Wilcox (Oracle) Cc: Paul Mackerras Cc: Ralph Campbell Cc: Signed-off-by: Andrew Morton --- mm/migrate_device.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 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 @@ -61,7 +62,7 @@ static int migrate_vma_collect_pmd(pmd_t struct migrate_vma *migrate = walk->private; struct vm_area_struct *vma = walk->vma; struct mm_struct *mm = vma->vm_mm; - unsigned long addr = start, unmapped = 0; + unsigned long addr = start; spinlock_t *ptl; pte_t *ptep; @@ -193,11 +194,10 @@ again: bool anon_exclusive; pte_t swp_pte; + flush_cache_page(vma, addr, pte_pfn(*ptep)); + pte = ptep_clear_flush(vma, addr, ptep); anon_exclusive = PageAnon(page) && PageAnonExclusive(page); if (anon_exclusive) { - flush_cache_page(vma, addr, pte_pfn(*ptep)); - ptep_clear_flush(vma, addr, ptep); - if (page_try_share_anon_rmap(page)) { set_pte_at(mm, addr, ptep, pte); unlock_page(page); @@ -205,12 +205,14 @@ again: mpfn = 0; goto next; } - } else { - 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( @@ -242,9 +244,6 @@ again: */ page_remove_rmap(page, vma, false); put_page(page); - - if (pte_present(pte)) - unmapped++; } else { put_page(page); mpfn = 0; @@ -257,10 +256,6 @@ next: arch_leave_lazy_mmu_mode(); pte_unmap_unlock(ptep - 1, ptl); - /* Only flush the TLB if we actually modified any entries */ - if (unmapped) - flush_tlb_range(walk->vma, start, end); - return 0; } _ 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