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 CB65EC43334 for ; Fri, 3 Jun 2022 14:56:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2D5A66B0072; Fri, 3 Jun 2022 10:56:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2878D8D0002; Fri, 3 Jun 2022 10:56:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 14BB48D0001; Fri, 3 Jun 2022 10:56:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 05AF36B0072 for ; Fri, 3 Jun 2022 10:56:51 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id CD207EB8 for ; Fri, 3 Jun 2022 14:56:50 +0000 (UTC) X-FDA: 79537226580.10.1A82D87 Received: from mail-ej1-f54.google.com (mail-ej1-f54.google.com [209.85.218.54]) by imf29.hostedemail.com (Postfix) with ESMTP id B7CBF120007 for ; Fri, 3 Jun 2022 14:56:36 +0000 (UTC) Received: by mail-ej1-f54.google.com with SMTP id s12so9215333ejx.3 for ; Fri, 03 Jun 2022 07:56:50 -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=xDGUdvx1pZTgyR7PJdBJDYNZdw+7CJ97LAoW275dhVs=; b=RSfJURm0QkP/9Vq/fBoprT4aTS2dTIKLUzM/4tcnKiBXK0q++Pvc6+HW05p0AqIUYG BY0IZq8t7He8sycbNSRuJgs0AE4a0HsC552jBOp6reIGUO0fkfJ56KuGWF+D1Pme6BOP OKhRndSEHmQaxthqzxydfKYJv9CQXEjn7sm70oJNM8qD/J/8nYgw4Qy6y/DpkCnqkloS 4cxKR8gPKRa/0Km47eUPxu3aWehYH6JGgXxX9MHVwla+IGMRIzzUzW2qftJRSjOY9uY5 qKs6sLNbJCWBbmWAxINU/Qy2nP8+oVKt2GIBxkdUv44hb/FEtTGkohnG2sYsEm2Y16Y+ sWhw== 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=xDGUdvx1pZTgyR7PJdBJDYNZdw+7CJ97LAoW275dhVs=; b=Ksq4c7UZXyVoUEaBZ54xs6WzVXi2mhSciuNOiskg7eNw+ZiLk1v0+pOdQ8SdV31WdB 1WrXzmRU9edghqr7bw0e/q6jMjiN0V7wSm4Mph2BakHIRUQvRYueOPqd4Yp+zR8fMdUx Ub5B/7SLjfTb0VThYLT/mFM1fHphW/GqNh3YVs9lZ7Kub1HSiGvnd+zQMLXP8Dimc1HH dy5tmgya19Qxy5wcMa6t/vmH0OLj9j77QMncq1YOgTzvY3eNOQl51wpaHJpvaujnFG/T XLus6SfpQ6hGqI9qGhZA4jb0CFCnVjwkBATZ93w/RoAnXTH8x4DfIk3vQ0B+ygH2Z737 054Q== X-Gm-Message-State: AOAM53380elp3EGw6iE0+h4Abg9hVMfKgEaFR8m/u8HbjE2TN7QRPVaQ CmisqECjOh6CHG1RFmSAXuk= X-Google-Smtp-Source: ABdhPJx0+/KUkuEWOOtQ4+NUTALnnZ3ui7c8UbzzYK8djtmi4+WlxYaLTp0wVIUGCmcnTLAXkWvg0Q== X-Received: by 2002:a17:907:3e18:b0:6fe:cf44:8692 with SMTP id hp24-20020a1709073e1800b006fecf448692mr9050521ejc.601.1654268209258; Fri, 03 Jun 2022 07:56:49 -0700 (PDT) Received: from orion.localdomain ([93.99.228.15]) by smtp.gmail.com with ESMTPSA id k9-20020a1709061c0900b006fec27575f1sm2890627ejg.123.2022.06.03.07.56.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Jun 2022 07:56:46 -0700 (PDT) Received: by orion.localdomain (Postfix, from userid 1003) id ABBE8A0013; Fri, 3 Jun 2022 16:57:20 +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 v4 1/2] [PATCH 1/2] mm: refactor of vma_merge() Date: Fri, 3 Jun 2022 16:57:18 +0200 Message-Id: <20220603145719.1012094-2-matenajakub@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220603145719.1012094-1-matenajakub@gmail.com> References: <20220603145719.1012094-1-matenajakub@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: gdjgrkz1dex4kuhsqep1p6mscdrmkzk3 X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=RSfJURm0; spf=pass (imf29.hostedemail.com: domain of matenajakub@gmail.com designates 209.85.218.54 as permitted sender) smtp.mailfrom=matenajakub@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: B7CBF120007 X-HE-Tag: 1654268196-892371 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 313b57d55a63..91100fdc400a 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 = find_vma(mm, prev ? prev->vm_end : 0); - 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 = find_vma(mm, next->vm_end); /* 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(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(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(res, vm_flags); + return res; } /* -- 2.35.1