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 55DEEC761AF for ; Wed, 22 Mar 2023 22:48:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229790AbjCVWsO (ORCPT ); Wed, 22 Mar 2023 18:48:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42528 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229656AbjCVWsM (ORCPT ); Wed, 22 Mar 2023 18:48:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46F3E113D9 for ; Wed, 22 Mar 2023 15:48:05 -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 D739F622C0 for ; Wed, 22 Mar 2023 22:48:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3820AC433EF; Wed, 22 Mar 2023 22:48:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1679525284; bh=mcU3u1EuUMmsOFcypa2HYz+o5D2IpvpGR9S2/73v4rI=; h=Date:To:From:Subject:From; b=CQF8GSq3yb7VMH0hXhWnZwW6S5WdTLtCW/IuR2YF5pGCLXF6HT+ttK64PnkhbawSt aSBgi8GdVm19TR9o/EotQVKZKKLBJr6MhpjZ9N6UVhwakfWjuGzNAEipnnqct6vrxf XBgI++VEgP5sox5QVsxGXZlOK/BvjRC44Tqn3A8Y= Date: Wed, 22 Mar 2023 15:48:03 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, vernon2gm@gmail.com, vbabka@suse.cz, Liam.Howlett@oracle.com, david@redhat.com, lstoakes@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-mmap-vma_merge-init-cleanup-be-explicit-about-the-non-mergeable-case.patch added to mm-unstable branch Message-Id: <20230322224804.3820AC433EF@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/mmap/vma_merge: init cleanup, be explicit about the non-mergeable case has been added to the -mm mm-unstable branch. Its filename is mm-mmap-vma_merge-init-cleanup-be-explicit-about-the-non-mergeable-case.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-vma_merge-init-cleanup-be-explicit-about-the-non-mergeable-case.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: Lorenzo Stoakes Subject: mm/mmap/vma_merge: init cleanup, be explicit about the non-mergeable case Date: Wed, 22 Mar 2023 20:19:00 +0000 Rather than setting err = -1 and only resetting if we hit merge cases, explicitly check the non-mergeable case to make it abundantly clear that we only proceed with the rest if something is mergeable, default err to 0 and only update if an error might occur. Move the merge_prev, merge_next cases closer to the logic determining curr, next and reorder initial variables so they are more logically grouped. This has no functional impact. Link: https://lkml.kernel.org/r/99259fbc6403e80e270e1cc4612abbc8620b121b.1679516210.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Vlastimil Babka Cc: David Hildenbrand Cc: Liam R. Howlett Cc: Matthew Wilcox (Oracle) Cc: Vernon Yang Signed-off-by: Andrew Morton --- --- a/mm/mmap.c~mm-mmap-vma_merge-init-cleanup-be-explicit-about-the-non-mergeable-case +++ a/mm/mmap.c @@ -909,18 +909,18 @@ struct vm_area_struct *vma_merge(struct struct vm_userfaultfd_ctx vm_userfaultfd_ctx, struct anon_vma_name *anon_name) { - pgoff_t pglen = (end - addr) >> PAGE_SHIFT; - pgoff_t vma_pgoff; struct vm_area_struct *curr, *next, *res; struct vm_area_struct *vma, *adjust, *remove, *remove2; - int err = -1; + struct vma_prepare vp; + pgoff_t vma_pgoff; + int err = 0; bool merge_prev = false; bool merge_next = false; bool vma_expanded = false; - struct vma_prepare vp; + unsigned long vma_start = addr; unsigned long vma_end = end; + pgoff_t pglen = (end - addr) >> PAGE_SHIFT; long adj_start = 0; - unsigned long vma_start = addr; validate_mm(mm); /* @@ -939,24 +939,14 @@ struct vm_area_struct *vma_merge(struct else next = NULL; /* case 5 */ - /* - * By default, we return prev. Cases 3, 4, 8 will instead return next - * and cases 3, 8 will also update vma to point at next. - */ - res = vma = prev; - - /* Verify some invariant that must be enforced by the caller. */ - VM_WARN_ON(prev && addr <= prev->vm_start); - VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end)); - VM_WARN_ON(addr >= end); - if (prev) { vma_start = prev->vm_start; vma_pgoff = prev->vm_pgoff; + /* Can we merge the predecessor? */ - if (prev->vm_end == addr && mpol_equal(vma_policy(prev), policy) + if (addr == prev->vm_end && mpol_equal(vma_policy(prev), policy) && can_vma_merge_after(prev, vm_flags, anon_vma, file, - pgoff, vm_userfaultfd_ctx, anon_name)) { + pgoff, vm_userfaultfd_ctx, anon_name)) { merge_prev = true; vma_prev(vmi); } @@ -964,13 +954,22 @@ struct vm_area_struct *vma_merge(struct /* Can we merge the successor? */ if (next && mpol_equal(policy, vma_policy(next)) && - can_vma_merge_before(next, vm_flags, - anon_vma, file, pgoff+pglen, + can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen, vm_userfaultfd_ctx, anon_name)) { merge_next = true; } + if (!merge_prev && !merge_next) + return NULL; /* Not mergeable. */ + + res = vma = prev; remove = remove2 = adjust = NULL; + + /* Verify some invariant that must be enforced by the caller. */ + VM_WARN_ON(prev && addr <= prev->vm_start); + VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end)); + VM_WARN_ON(addr >= end); + /* Can we merge both the predecessor and the successor? */ if (merge_prev && merge_next && is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) { @@ -983,8 +982,7 @@ struct vm_area_struct *vma_merge(struct if (!next->anon_vma) err = dup_anon_vma(prev, curr); } - } else if (merge_prev) { - err = 0; /* case 2 */ + } else if (merge_prev) { /* case 2 */ if (curr) { err = dup_anon_vma(prev, curr); if (end == curr->vm_end) { /* case 7 */ @@ -994,7 +992,7 @@ struct vm_area_struct *vma_merge(struct adj_start = (end - curr->vm_start); } } - } else if (merge_next) { + } else { /* merge_next */ res = next; if (prev && addr < prev->vm_end) { /* case 4 */ vma_end = addr; @@ -1010,7 +1008,6 @@ struct vm_area_struct *vma_merge(struct vma_start = addr; vma_end = next->vm_end; vma_pgoff = next->vm_pgoff; - err = 0; if (curr) { /* case 8 */ vma_pgoff = curr->vm_pgoff; remove = curr; @@ -1019,7 +1016,7 @@ struct vm_area_struct *vma_merge(struct } } - /* Cannot merge or error in anon_vma clone */ + /* Error in anon_vma clone. */ if (err) return NULL; _ Patches currently in -mm which might be from lstoakes@gmail.com are mm-prefer-xxx_page-alloc-free-functions-for-order-0-pages.patch mm-refactor-do_fault_around.patch mm-pefer-fault_around_pages-to-fault_around_bytes.patch maintainers-add-myself-as-vmalloc-reviewer.patch mm-remove-unused-vmf_insert_mixed_prot.patch mm-remove-vmf_insert_pfn_xxx_prot-for-huge-page-table-entries.patch drm-ttm-remove-comment-referencing-now-removed-vmf_insert_mixed_prot.patch fs-proc-kcore-avoid-bounce-buffer-for-ktext-data.patch fs-proc-kcore-convert-read_kcore-to-read_kcore_iter.patch iov_iter-add-copy_page_to_iter_atomic.patch mm-vmalloc-convert-vread-to-vread_iter.patch mm-mmap-vma_merge-further-improve-prev-next-vma-naming.patch mm-mmap-vma_merge-fold-curr-next-assignment-logic.patch mm-mmap-vma_merge-explicitly-assign-res-vma-extend-invariants.patch mm-mmap-vma_merge-init-cleanup-be-explicit-about-the-non-mergeable-case.patch