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 4AE24C7EE25 for ; Fri, 9 Jun 2023 20:11:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230316AbjFIULa (ORCPT ); Fri, 9 Jun 2023 16:11:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230432AbjFIUL0 (ORCPT ); Fri, 9 Jun 2023 16:11:26 -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 71A3E1A1 for ; Fri, 9 Jun 2023 13:11:25 -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 05E1F65B88 for ; Fri, 9 Jun 2023 20:11:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 57EC1C433EF; Fri, 9 Jun 2023 20:11:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1686341484; bh=44tTiHGT10KwZiH/Ua243HCc5sE/drwacBZoLCdyDSQ=; h=Date:To:From:Subject:From; b=agjIyIyXEn4NLDefkPQQXXJajo1qMlOUu9Uofs5Eoxx6IN7jChOocmq6TS91ibAz9 p9f8yYahZzoWXfrn1WR7o2X4JzXpiPMo5hvHkmOLSOnrBBql47uSu2gK7+n0tQYSMy sxRnyPrmqjkypH8GPRszwWtgX/sn5yIcyeBDIh6I= Date: Fri, 09 Jun 2023 13:11:23 -0700 To: mm-commits@vger.kernel.org, zhengqi.arch@bytedance.com, zackr@vmware.com, yuzhao@google.com, ying.huang@intel.com, willy@infradead.org, will@kernel.org, thomas.hellstrom@linux.intel.com, surenb@google.com, steven.price@arm.com, song@kernel.org, sj@kernel.org, shy828301@gmail.com, ryan.roberts@arm.com, rppt@kernel.org, rcampbell@nvidia.com, peterz@infradead.org, peterx@redhat.com, pasha.tatashin@soleen.com, naoya.horiguchi@nec.com, minchan@kernel.org, mike.kravetz@oracle.com, mgorman@techsingularity.net, lstoakes@gmail.com, linmiaohe@huawei.com, kirill.shutemov@linux.intel.com, jgg@ziepe.ca, ira.weiny@intel.com, hch@infradead.org, david@redhat.com, christophe.leroy@csgroup.eu, axelrasmussen@google.com, apopple@nvidia.com, anshuman.khandual@arm.com, hughd@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-mprotect-delete-pmd_none_or_clear_bad_unless_trans_huge.patch added to mm-unstable branch Message-Id: <20230609201124.57EC1C433EF@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/mprotect: delete pmd_none_or_clear_bad_unless_trans_huge() has been added to the -mm mm-unstable branch. Its filename is mm-mprotect-delete-pmd_none_or_clear_bad_unless_trans_huge.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mprotect-delete-pmd_none_or_clear_bad_unless_trans_huge.patch This patch will later appear in the mm-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: Hugh Dickins Subject: mm/mprotect: delete pmd_none_or_clear_bad_unless_trans_huge() Date: Thu, 8 Jun 2023 18:30:48 -0700 (PDT) change_pmd_range() had special pmd_none_or_clear_bad_unless_trans_huge(), required to avoid "bad" choices when setting automatic NUMA hinting under mmap_read_lock(); but most of that is already covered in pte_offset_map() now. change_pmd_range() just wants a pmd_none() check before wasting time on MMU notifiers, then checks on the read-once _pmd value to work out what's needed for huge cases. If change_pte_range() returns -EAGAIN to retry if pte_offset_map_lock() fails, nothing more special is needed. Link: https://lkml.kernel.org/r/725a42a9-91e9-c868-925-e3a5fd40bb4f@google.com Signed-off-by: Hugh Dickins Cc: Alistair Popple Cc: Anshuman Khandual Cc: Axel Rasmussen Cc: Christophe Leroy Cc: Christoph Hellwig Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Ira Weiny Cc: Jason Gunthorpe Cc: Kirill A. Shutemov Cc: Lorenzo Stoakes Cc: Matthew Wilcox Cc: Mel Gorman Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Minchan Kim Cc: Naoya Horiguchi Cc: Pavel Tatashin Cc: Peter Xu Cc: Peter Zijlstra Cc: Qi Zheng Cc: Ralph Campbell Cc: Ryan Roberts Cc: SeongJae Park Cc: Song Liu Cc: Steven Price Cc: Suren Baghdasaryan Cc: Thomas Hellström Cc: Will Deacon Cc: Yang Shi Cc: Yu Zhao Cc: Zack Rusin Signed-off-by: Andrew Morton --- mm/mprotect.c | 74 +++++++++++------------------------------------- 1 file changed, 17 insertions(+), 57 deletions(-) --- a/mm/mprotect.c~mm-mprotect-delete-pmd_none_or_clear_bad_unless_trans_huge +++ a/mm/mprotect.c @@ -93,22 +93,9 @@ static long change_pte_range(struct mmu_ bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; tlb_change_page_size(tlb, PAGE_SIZE); - - /* - * Can be called with only the mmap_lock for reading by - * prot_numa so we must check the pmd isn't constantly - * changing from under us from pmd_none to pmd_trans_huge - * and/or the other way around. - */ - if (pmd_trans_unstable(pmd)) - return 0; - - /* - * The pmd points to a regular pte so the pmd can't change - * from under us even if the mmap_lock is only hold for - * reading. - */ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + if (!pte) + return -EAGAIN; /* Get target node for single threaded private VMAs */ if (prot_numa && !(vma->vm_flags & VM_SHARED) && @@ -302,26 +289,6 @@ static long change_pte_range(struct mmu_ } /* - * Used when setting automatic NUMA hinting protection where it is - * critical that a numa hinting PMD is not confused with a bad PMD. - */ -static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd) -{ - pmd_t pmdval = pmdp_get_lockless(pmd); - - if (pmd_none(pmdval)) - return 1; - if (pmd_trans_huge(pmdval)) - return 0; - if (unlikely(pmd_bad(pmdval))) { - pmd_clear_bad(pmd); - return 1; - } - - return 0; -} - -/* * Return true if we want to split THPs into PTE mappings in change * protection procedure, false otherwise. */ @@ -398,7 +365,8 @@ static inline long change_pmd_range(stru pmd = pmd_offset(pud, addr); do { long ret; - + pmd_t _pmd; +again: next = pmd_addr_end(addr, end); ret = change_pmd_prepare(vma, pmd, cp_flags); @@ -406,16 +374,8 @@ static inline long change_pmd_range(stru pages = ret; break; } - /* - * Automatic NUMA balancing walks the tables with mmap_lock - * held for read. It's possible a parallel update to occur - * between pmd_trans_huge() and a pmd_none_or_clear_bad() - * check leading to a false positive and clearing. - * Hence, it's necessary to atomically read the PMD value - * for all the checks. - */ - if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) && - pmd_none_or_clear_bad_unless_trans_huge(pmd)) + + if (pmd_none(*pmd)) goto next; /* invoke the mmu notifier if the pmd is populated */ @@ -426,7 +386,8 @@ static inline long change_pmd_range(stru mmu_notifier_invalidate_range_start(&range); } - if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { + _pmd = pmdp_get_lockless(pmd); + if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) { if ((next - addr != HPAGE_PMD_SIZE) || pgtable_split_needed(vma, cp_flags)) { __split_huge_pmd(vma, pmd, addr, false, NULL); @@ -441,15 +402,10 @@ static inline long change_pmd_range(stru break; } } else { - /* - * change_huge_pmd() does not defer TLB flushes, - * so no need to propagate the tlb argument. - */ - int nr_ptes = change_huge_pmd(tlb, vma, pmd, + ret = change_huge_pmd(tlb, vma, pmd, addr, newprot, cp_flags); - - if (nr_ptes) { - if (nr_ptes == HPAGE_PMD_NR) { + if (ret) { + if (ret == HPAGE_PMD_NR) { pages += HPAGE_PMD_NR; nr_huge_updates++; } @@ -460,8 +416,12 @@ static inline long change_pmd_range(stru } /* fall through, the trans huge pmd just split */ } - pages += change_pte_range(tlb, vma, pmd, addr, next, - newprot, cp_flags); + + ret = change_pte_range(tlb, vma, pmd, addr, next, newprot, + cp_flags); + if (ret < 0) + goto again; + pages += ret; next: cond_resched(); } while (pmd++, addr = next, addr != end); _ Patches currently in -mm which might be from hughd@google.com are arm-allow-pte_offset_map-to-fail.patch arm64-allow-pte_offset_map-to-fail.patch arm64-hugetlb-pte_alloc_huge-pte_offset_huge.patch ia64-hugetlb-pte_alloc_huge-pte_offset_huge.patch m68k-allow-pte_offset_map-to-fail.patch microblaze-allow-pte_offset_map-to-fail.patch mips-update_mmu_cache-can-replace-__update_tlb.patch mips-update_mmu_cache-can-replace-__update_tlb-fix.patch parisc-add-pte_unmap-to-balance-get_ptep.patch parisc-unmap_uncached_pte-use-pte_offset_kernel.patch parisc-hugetlb-pte_alloc_huge-pte_offset_huge.patch powerpc-kvmppc_unmap_free_pmd-pte_offset_kernel.patch powerpc-allow-pte_offset_map-to-fail.patch powerpc-hugetlb-pte_alloc_huge.patch riscv-hugetlb-pte_alloc_huge-pte_offset_huge.patch s390-allow-pte_offset_map_lock-to-fail.patch s390-gmap-use-pte_unmap_unlock-not-spin_unlock.patch sh-hugetlb-pte_alloc_huge-pte_offset_huge.patch sparc-hugetlb-pte_alloc_huge-pte_offset_huge.patch sparc-allow-pte_offset_map-to-fail.patch sparc-iounit-and-iommu-use-pte_offset_kernel.patch x86-allow-get_locked_pte-to-fail.patch x86-sme_populate_pgd-use-pte_offset_kernel.patch xtensa-add-pte_unmap-to-balance-pte_offset_map.patch mm-use-pmdp_get_lockless-without-surplus-barrier.patch mm-migrate-remove-cruft-from-migration_entry_waits.patch mm-pgtable-kmap_local_page-instead-of-kmap_atomic.patch mm-pgtable-allow-pte_offset_map-to-fail.patch mm-filemap-allow-pte_offset_map_lock-to-fail.patch mm-page_vma_mapped-delete-bogosity-in-page_vma_mapped_walk.patch mm-page_vma_mapped-reformat-map_pte-with-less-indentation.patch mm-page_vma_mapped-pte_offset_map_nolock-not-pte_lockptr.patch mm-pagewalkers-action_again-if-pte_offset_map_lock-fails.patch mm-pagewalk-walk_pte_range-allow-for-pte_offset_map.patch mm-vmwgfx-simplify-pmd-pud-mapping-dirty-helpers.patch mm-vmalloc-vmalloc_to_page-use-pte_offset_kernel.patch mm-hmm-retry-if-pte_offset_map-fails.patch mm-userfaultfd-retry-if-pte_offset_map-fails.patch mm-userfaultfd-allow-pte_offset_map_lock-to-fail.patch mm-debug_vm_pgtablepage_table_check-warn-pte-map-fails.patch mm-various-give-up-if-pte_offset_map-fails.patch mm-mprotect-delete-pmd_none_or_clear_bad_unless_trans_huge.patch mm-mremap-retry-if-either-pte_offset_map_lock-fails.patch mm-madvise-clean-up-pte_offset_map_lock-scans.patch mm-madvise-clean-up-force_shm_swapin_readahead.patch mm-swapoff-allow-pte_offset_map-to-fail.patch mm-mglru-allow-pte_offset_map_nolock-to-fail.patch mm-migrate_device-allow-pte_offset_map_lock-to-fail.patch mm-gup-remove-foll_split_pmd-use-of-pmd_trans_unstable.patch mm-huge_memory-split-huge-pmd-under-one-pte_offset_map.patch mm-khugepaged-allow-pte_offset_map-to-fail.patch mm-memory-allow-pte_offset_map-to-fail.patch mm-memory-handle_pte_fault-use-pte_offset_map_nolock.patch mm-pgtable-delete-pmd_trans_unstable-and-friends.patch mm-swap-swap_vma_readahead-do-the-pte_offset_map.patch perf-core-allow-pte_offset_map-to-fail.patch