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 76F13C4708D for ; Thu, 1 Dec 2022 00:03:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230005AbiLAADx (ORCPT ); Wed, 30 Nov 2022 19:03:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46768 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230184AbiLAACc (ORCPT ); Wed, 30 Nov 2022 19:02:32 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F3838C464 for ; Wed, 30 Nov 2022 16:01:12 -0800 (PST) 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 5D93FB81D12 for ; Thu, 1 Dec 2022 00:01:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0056CC433D6; Thu, 1 Dec 2022 00:01:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1669852870; bh=Hpgsk9MhueKvHtq6ur9mxpm9g3kXkiouORtqUOZtPU0=; h=Date:To:From:Subject:From; b=XEabrllQj9UYwzxJN0t7rGNSQ/iyTfszvrQwYBpApUGNqN+eSisZn+mb7LKtw5hw+ ap9AUwI8+qfM1iucZWOZcktBqrwf1+Zx0I9BHoxCILd49OHkhuo/Pw1D2APooTiTeb z52B0GpqmNgNq0lHEu31j27mimafS9TegvXAH1Vs= Date: Wed, 30 Nov 2022 16:01:09 -0800 To: mm-commits@vger.kernel.org, vbabka@suse.cz, torvalds@linux-foundation.org, rppt@kernel.org, peterx@redhat.com, npiggin@gmail.com, namit@vmware.com, mpe@ellerman.id.au, mgorman@techsingularity.net, hughd@google.com, david@fromorbit.com, anshuman.khandual@arm.com, aarcange@redhat.com, david@redhat.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-huge_memory-try-avoiding-write-faults-when-changing-pmd-protection.patch removed from -mm tree Message-Id: <20221201000110.0056CC433D6@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm/huge_memory: try avoiding write faults when changing PMD protection has been removed from the -mm tree. Its filename was mm-huge_memory-try-avoiding-write-faults-when-changing-pmd-protection.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: David Hildenbrand Subject: mm/huge_memory: try avoiding write faults when changing PMD protection Date: Tue, 8 Nov 2022 18:46:48 +0100 Let's replicate what we have for PTEs in can_change_pte_writable() also for PMDs. While this might look like a pure performance improvement, we'll us this to get rid of savedwrite handling in do_huge_pmd_numa_page() next. Place do_huge_pmd_numa_page() strategically good for that purpose. Note that MM_CP_TRY_CHANGE_WRITABLE is currently only set when we come via mprotect_fixup(). Link: https://lkml.kernel.org/r/20221108174652.198904-4-david@redhat.com Signed-off-by: David Hildenbrand Cc: Andrea Arcangeli Cc: Anshuman Khandual Cc: Dave Chinner Cc: Hugh Dickins Cc: Linus Torvalds Cc: Mel Gorman Cc: Michael Ellerman Cc: Mike Rapoport Cc: Nadav Amit Cc: Nicholas Piggin Cc: Peter Xu Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/huge_memory.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-try-avoiding-write-faults-when-changing-pmd-protection +++ a/mm/huge_memory.c @@ -1390,6 +1390,36 @@ fallback: return VM_FAULT_FALLBACK; } +static inline bool can_change_pmd_writable(struct vm_area_struct *vma, + unsigned long addr, pmd_t pmd) +{ + struct page *page; + + if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) + return false; + + /* Don't touch entries that are not even readable (NUMA hinting). */ + if (pmd_protnone(pmd)) + return false; + + /* Do we need write faults for softdirty tracking? */ + if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) + return false; + + /* Do we need write faults for uffd-wp tracking? */ + if (userfaultfd_huge_pmd_wp(vma, pmd)) + return false; + + if (!(vma->vm_flags & VM_SHARED)) { + /* See can_change_pte_writable(). */ + page = vm_normal_page_pmd(vma, addr, pmd); + return page && PageAnon(page) && PageAnonExclusive(page); + } + + /* See can_change_pte_writable(). */ + return pmd_dirty(pmd); +} + /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, struct vm_area_struct *vma, @@ -1893,13 +1923,17 @@ int change_huge_pmd(struct mmu_gather *t */ entry = pmd_clear_uffd_wp(entry); } + + /* See change_pte_range(). */ + if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && + can_change_pmd_writable(vma, addr, entry)) + entry = pmd_mkwrite(entry); + ret = HPAGE_PMD_NR; set_pmd_at(mm, addr, pmd, entry); if (huge_pmd_needs_flush(oldpmd, entry)) tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); - - BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); unlock: spin_unlock(ptl); return ret; _ Patches currently in -mm which might be from david@redhat.com are selftests-vm-add-ksm-unmerge-tests.patch mm-pagewalk-dont-trigger-test_walk-in-walk_page_vma.patch selftests-vm-add-test-to-measure-madv_unmergeable-performance.patch mm-ksm-simplify-break_ksm-to-not-rely-on-vm_fault_write.patch mm-remove-vm_fault_write.patch mm-ksm-fix-ksm-cow-breaking-with-userfaultfd-wp-via-fault_flag_unshare.patch mm-pagewalk-add-walk_page_range_vma.patch mm-ksm-convert-break_ksm-to-use-walk_page_range_vma.patch mm-gup-remove-foll_migration.patch