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[184.144.111.238]) by smtp.gmail.com with ESMTPSA id 74sm5298585qkh.42.2021.07.20.08.57.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Jul 2021 08:57:02 -0700 (PDT) From: Peter Xu To: stable@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Igor Raits , peterx@redhat.com, Hillf Danton , Axel Rasmussen , Hugh Dickins , Andrew Morton Subject: [PATCH stable 5.10.y 1/2] mm/thp: simplify copying of huge zero page pmd when fork Date: Tue, 20 Jul 2021 11:56:56 -0400 Message-Id: <20210720155657.499127-2-peterx@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210720155657.499127-1-peterx@redhat.com> References: <796cbb7-5a1c-1ba0-dde5-479aba8224f2@google.com> <20210720155657.499127-1-peterx@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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 Signed-off-by: Linus Torvalds (cherry picked from commit 5fc7a5f6fd04bc18f309d9f979b32ef7d1d0a997) Signed-off-by: Peter Xu --- mm/huge_memory.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9fe622ff2fc4..8763c4e346cb 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1074,17 +1074,13 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, * 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); @@ -1110,6 +1106,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 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);