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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id ADE16C433EF for ; Fri, 27 May 2022 21:16:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0E3BE8D0002; Fri, 27 May 2022 17:16:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0226D8D0007; Fri, 27 May 2022 17:16:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DA1FB8D0002; Fri, 27 May 2022 17:16:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id C11BE8D0002 for ; Fri, 27 May 2022 17:16:43 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 954A961747 for ; Fri, 27 May 2022 21:16:43 +0000 (UTC) X-FDA: 79512782286.16.ED1462D Received: from mail-ej1-f52.google.com (mail-ej1-f52.google.com [209.85.218.52]) by imf01.hostedemail.com (Postfix) with ESMTP id 608E94004F for ; Fri, 27 May 2022 21:16:38 +0000 (UTC) Received: by mail-ej1-f52.google.com with SMTP id y13so10971079eje.2 for ; Fri, 27 May 2022 14:16:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ru3bkI46cGQXTo5hSsyPFl2jKgUjs/czASVw2IToYVQ=; b=EKUNVPeMnRd274p6w7NzjRvrzG+1Vzb7NNsyThVrB39jtt3BmGdNB/FDIDQ8Je0Wkx 79yb+Ur+1BNH3EWYCuXMnj0n4tKugWeTV/s6bQcmOjS/M4BzSwrdWhCKYflx5cS6JWwZ 6DG2nqaH9HMKivoo/hcCev2L4qhr4MGxmXJuLLmrTD17/fsjm24k+7Z6PCvgZjDVyqex Bx2LBogNAW2x+xspwzeZH54qtfWtb71D/v7ScGfgxdAqBegWi/gd0KzBvqIG2+af8VY0 kcnb24+Fo8IxXa+Yi9DSTzWv7OhloaWyqJX/a0queK5D4HGlSoS2mC1nVepbi8KmB/pm bUFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ru3bkI46cGQXTo5hSsyPFl2jKgUjs/czASVw2IToYVQ=; b=FcO6Du50nz26VuFS4JkcxYcUYaCNvWzCpWZ7HWpN83DyEWdkzZLeQ1SYZeNtDd8Rpm SoF3MC2xQRtUkJ++IfIZhbh+EirP4ETt33WXjA83RMrYPuL508dxRcgjacTYS9puyZTX 4yMA3Pq1Rb7ljr7zd5U02PqRzBSHAShVYgkqvOiDmLvdCL9AE/Z6coZoTPn86d5UDpha pC3TDeiRplk6fvE+o0994+d2I7VnphLLq7KixKJce0TUukd2GWeNfCzJV88735qHZfCf onxJHfDmPvh++chvbaA2j8jt5R5InSRZvE5VdK9n4yL7uRsH7Se6NK8IS3dtQQQZL2ze 8uKg== X-Gm-Message-State: AOAM5331V99KvfGuik8W++vGfIK7gfBZYWnQFRmMmXELdqzO/XrH1CCL VIM92FmJgoeqJElFqbOXtfg= X-Google-Smtp-Source: ABdhPJw7il9s5g0FRdrNg4rA7uzSJ8eWBPX96AILajtYjt+pBgDXP+GyifzqQ2lxEqw4rM0JJ4VDpA== X-Received: by 2002:a17:907:3e09:b0:6ff:20f:9b1a with SMTP id hp9-20020a1709073e0900b006ff020f9b1amr19318212ejc.679.1653686201666; Fri, 27 May 2022 14:16:41 -0700 (PDT) Received: from orion.localdomain ([93.99.228.15]) by smtp.gmail.com with ESMTPSA id m22-20020a17090679d600b006f3ef214da9sm1814854ejo.15.2022.05.27.14.16.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 May 2022 14:16:40 -0700 (PDT) Received: by orion.localdomain (Postfix, from userid 1003) id 11BDFA0018; Fri, 27 May 2022 23:17:10 +0200 (CEST) From: =?UTF-8?q?Jakub=20Mat=C4=9Bna?= To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, vbabka@suse.cz, mhocko@kernel.org, mgorman@techsingularity.net, willy@infradead.org, liam.howlett@oracle.com, hughd@google.com, kirill@shutemov.name, riel@surriel.com, rostedt@goodmis.org, peterz@infradead.org, =?UTF-8?q?Jakub=20Mat=C4=9Bna?= Subject: [PATCH v2 1/2] [PATCH 1/2] mm: refactor of vma_merge() Date: Fri, 27 May 2022 23:17:07 +0200 Message-Id: <20220527211708.839033-2-matenajakub@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220527211708.839033-1-matenajakub@gmail.com> References: <20220527211708.839033-1-matenajakub@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: 4bbsghm1saozqtycsktbdaob5cp4bkej Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=EKUNVPeM; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf01.hostedemail.com: domain of matenajakub@gmail.com designates 209.85.218.52 as permitted sender) smtp.mailfrom=matenajakub@gmail.com X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 608E94004F X-HE-Tag: 1653686198-613881 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Refactor vma_merge() to make it shorter and more understandable. Main change is the elimination of code duplicity in the case of merge next check. This is done by first doing checks and caching the results before executing the merge itself. The variable 'area' is divided into 'mid' and 'res' as previously it was used for two purposes, as the middle VMA between prev and next and also as the result of the merge itself. Exit paths are also unified. Signed-off-by: Jakub Matěna --- mm/mmap.c | 87 +++++++++++++++++++++++-------------------------------- 1 file changed, 37 insertions(+), 50 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 3aa839f81e63..bd0dde2ad3e2 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1170,8 +1170,10 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, struct anon_vma_name *anon_name) { pgoff_t pglen = (end - addr) >> PAGE_SHIFT; - struct vm_area_struct *area, *next; - int err; + struct vm_area_struct *mid, *next, *res; + int err = -1; + bool merge_prev = false; + bool merge_next = false; /* * We later require that vma->vm_flags == vm_flags, @@ -1181,75 +1183,60 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, return NULL; next = vma_next(mm, prev); - area = next; - if (area && area->vm_end == end) /* cases 6, 7, 8 */ + mid = next; + if (next && next->vm_end == end) /* cases 6, 7, 8 */ next = next->vm_next; /* verify some invariant that must be enforced by the caller */ VM_WARN_ON(prev && addr <= prev->vm_start); - VM_WARN_ON(area && end > area->vm_end); + VM_WARN_ON(mid && end > mid->vm_end); VM_WARN_ON(addr >= end); - /* - * Can it merge with the predecessor? - */ + /* Can we merge the predecessor? */ if (prev && prev->vm_end == addr && mpol_equal(vma_policy(prev), policy) && can_vma_merge_after(prev, vm_flags, anon_vma, file, pgoff, vm_userfaultfd_ctx, anon_name)) { - /* - * OK, it can. Can we now merge in the successor as well? - */ - if (next && end == next->vm_start && - mpol_equal(policy, vma_policy(next)) && - can_vma_merge_before(next, vm_flags, - anon_vma, file, - pgoff+pglen, - vm_userfaultfd_ctx, anon_name) && - is_mergeable_anon_vma(prev->anon_vma, - next->anon_vma, NULL)) { - /* cases 1, 6 */ - err = __vma_adjust(prev, prev->vm_start, - next->vm_end, prev->vm_pgoff, NULL, - prev); - } else /* cases 2, 5, 7 */ - err = __vma_adjust(prev, prev->vm_start, - end, prev->vm_pgoff, NULL, prev); - if (err) - return NULL; - khugepaged_enter_vma_merge(prev, vm_flags); - return prev; + merge_prev = true; } - - /* - * Can this new request be merged in front of next? - */ + /* Can we merge the successor? */ if (next && end == next->vm_start && mpol_equal(policy, vma_policy(next)) && can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen, vm_userfaultfd_ctx, anon_name)) { + merge_next = true; + } + /* 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)) { /* cases 1, 6 */ + err = __vma_adjust(prev, prev->vm_start, + next->vm_end, prev->vm_pgoff, NULL, + prev); + res = prev; + } else if (merge_prev) { /* cases 2, 5, 7 */ + err = __vma_adjust(prev, prev->vm_start, + end, prev->vm_pgoff, NULL, prev); + res = prev; + } else if (merge_next) { if (prev && addr < prev->vm_end) /* case 4 */ err = __vma_adjust(prev, prev->vm_start, - addr, prev->vm_pgoff, NULL, next); - else { /* cases 3, 8 */ - err = __vma_adjust(area, addr, next->vm_end, - next->vm_pgoff - pglen, NULL, next); - /* - * In case 3 area is already equal to next and - * this is a noop, but in case 8 "area" has - * been removed and next was expanded over it. - */ - area = next; - } - if (err) - return NULL; - khugepaged_enter_vma_merge(area, vm_flags); - return area; + addr, prev->vm_pgoff, NULL, next); + else /* cases 3, 8 */ + err = __vma_adjust(mid, addr, next->vm_end, + next->vm_pgoff - pglen, NULL, next); + res = next; } - return NULL; + /* + * Cannot merge with predecessor or successor or error in __vma_adjust? + */ + if (err) + return NULL; + khugepaged_enter_vma_merge(res, vm_flags); + return res; } /* -- 2.35.1