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 0CC84C433EF for ; Thu, 14 Apr 2022 20:56:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242814AbiDNU6b (ORCPT ); Thu, 14 Apr 2022 16:58:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231129AbiDNU6a (ORCPT ); Thu, 14 Apr 2022 16:58:30 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7862FCD648 for ; Thu, 14 Apr 2022 13:56:04 -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 23FECB82A67 for ; Thu, 14 Apr 2022 20:56:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5234C385A5; Thu, 14 Apr 2022 20:56:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1649969761; bh=l89+WUhC0Gu+zPZLsWUr5d8P7O6W9rpk6TwUnJZWgJ4=; h=Date:To:From:Subject:From; b=c0twqZpzKSCE5SUOKdrCXZ8FTIYOWZ/mv5Zj0ozLEtMkZHfBJKwP88plVtkQfWqTE eiazdffPzk5SOOruSyJ9HQGJbWQfOnV37OszMK/DUQOpO9PA5nomCeGys75FbYsyg8 GefbQpPomevl3/snEYdmVH72zwJaDhmHWEWIBuqk= Date: Thu, 14 Apr 2022 13:56:00 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, rppt@linux.vnet.ibm.com, nadav.amit@gmail.com, m.szyprowski@samsung.com, mike.kravetz@oracle.com, kirill@shutemov.name, jglisse@redhat.com, hughd@google.com, david@redhat.com, axelrasmussen@google.com, apopple@nvidia.com, aarcange@redhat.com, peterx@redhat.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-check-against-orig_pte-for-finish_fault-fix.patch added to -mm tree Message-Id: <20220414205601.A5234C385A5@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-check-against-orig_pte-for-finish_fault-fix has been added to the -mm tree. Its filename is mm-check-against-orig_pte-for-finish_fault-fix.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-check-against-orig_pte-for-finish_fault-fix.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-check-against-orig_pte-for-finish_fault-fix.patch 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 and is updated there every 3-4 working days ------------------------------------------------------ From: Peter Xu Subject: mm-check-against-orig_pte-for-finish_fault-fix fix crash reported by Marek Link: https://lkml.kernel.org/r/Ylb9rXJyPm8/ao8f@xz-m1.local Signed-off-by: Peter Xu Reported-by: Marek Szyprowski Tested-by: Marek Szyprowski Cc: Alistair Popple Cc: Andrea Arcangeli Cc: Axel Rasmussen Cc: David Hildenbrand Cc: Hugh Dickins Cc: Jerome Glisse Cc: "Kirill A . Shutemov" Cc: Matthew Wilcox Cc: Mike Kravetz Cc: Mike Rapoport Cc: Nadav Amit Signed-off-by: Andrew Morton --- --- a/include/linux/mm_types.h~mm-check-against-orig_pte-for-finish_fault-fix +++ a/include/linux/mm_types.h @@ -814,6 +814,8 @@ typedef struct { * @FAULT_FLAG_UNSHARE: The fault is an unsharing request to unshare (and mark * exclusive) a possibly shared anonymous page that is * mapped R/O. + * @FAULT_FLAG_ORIG_PTE_VALID: whether the fault has vmf->orig_pte cached. + * We should only access orig_pte if this flag set. * * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify * whether we would allow page faults to retry by specifying these two @@ -850,6 +852,7 @@ enum fault_flag { FAULT_FLAG_INSTRUCTION = 1 << 8, FAULT_FLAG_INTERRUPTIBLE = 1 << 9, FAULT_FLAG_UNSHARE = 1 << 10, + FAULT_FLAG_ORIG_PTE_VALID = 1 << 11, }; #endif /* _LINUX_MM_TYPES_H */ --- a/mm/memory.c~mm-check-against-orig_pte-for-finish_fault-fix +++ a/mm/memory.c @@ -4194,6 +4194,15 @@ void do_set_pte(struct vm_fault *vmf, st set_pte_at(vma->vm_mm, addr, vmf->pte, entry); } +static bool vmf_pte_changed(struct vm_fault *vmf) +{ + if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID) { + return !pte_same(*vmf->pte, vmf->orig_pte); + } + + return !pte_none(*vmf->pte); +} + /** * finish_fault - finish page fault once we have prepared the page to fault * @@ -4252,7 +4261,7 @@ vm_fault_t finish_fault(struct vm_fault vmf->address, &vmf->ptl); ret = 0; /* Re-check under ptl */ - if (likely(pte_same(*vmf->pte, vmf->orig_pte))) + if (likely(!vmf_pte_changed(vmf))) do_set_pte(vmf, page, vmf->address); else ret = VM_FAULT_NOPAGE; @@ -4720,13 +4729,7 @@ static vm_fault_t handle_pte_fault(struc * concurrent faults and from rmap lookups. */ vmf->pte = NULL; - /* - * Always initialize orig_pte. This matches with below - * code to have orig_pte to be the none pte if pte==NULL. - * This makes the rest code to be always safe to reference - * it, e.g. in finish_fault() we'll detect pte changes. - */ - pte_clear(vmf->vma->vm_mm, vmf->address, &vmf->orig_pte); + vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID; } else { /* * If a huge pmd materialized under us just retry later. Use @@ -4750,6 +4753,7 @@ static vm_fault_t handle_pte_fault(struc */ vmf->pte = pte_offset_map(vmf->pmd, vmf->address); vmf->orig_pte = *vmf->pte; + vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID; /* * some architectures can have larger ptes than wordsize, _ Patches currently in -mm which might be from peterx@redhat.com are mm-remove-stub-for-non_swap_entry.patch mm-introduce-pte_marker-swap-entry.patch mm-introduce-pte_marker-swap-entry-fix.patch mm-teach-core-mm-about-pte-markers.patch mm-check-against-orig_pte-for-finish_fault.patch mm-check-against-orig_pte-for-finish_fault-fix.patch mm-uffd-pte_marker_uffd_wp.patch mm-uffd-pte_marker_uffd_wp-fix.patch mm-shmem-take-care-of-uffdio_copy_mode_wp.patch mm-shmem-handle-uffd-wp-special-pte-in-page-fault-handler.patch mm-shmem-persist-uffd-wp-bit-across-zapping-for-file-backed.patch mm-shmem-allow-uffd-wr-protect-none-pte-for-file-backed-mem.patch mm-shmem-allows-file-back-mem-to-be-uffd-wr-protected-on-thps.patch mm-shmem-handle-uffd-wp-during-fork.patch mm-hugetlb-introduce-huge-pte-version-of-uffd-wp-helpers.patch mm-hugetlb-hook-page-faults-for-uffd-write-protection.patch mm-hugetlb-take-care-of-uffdio_copy_mode_wp.patch mm-hugetlb-handle-uffdio_writeprotect.patch mm-hugetlb-handle-pte-markers-in-page-faults.patch mm-hugetlb-allow-uffd-wr-protect-none-ptes.patch mm-hugetlb-only-drop-uffd-wp-special-pte-if-required.patch mm-hugetlb-only-drop-uffd-wp-special-pte-if-required-fix.patch mm-hugetlb-handle-uffd-wp-during-fork.patch mm-khugepaged-dont-recycle-vma-pgtable-if-uffd-wp-registered.patch mm-pagemap-recognize-uffd-wp-bit-for-shmem-hugetlbfs.patch mm-uffd-enable-write-protection-for-shmem-hugetlbfs.patch mm-enable-pte-markers-by-default.patch selftests-uffd-enable-uffd-wp-for-shmem-hugetlbfs.patch