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 94770C433EF for ; Mon, 16 May 2022 12:53:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3B9B16B0072; Mon, 16 May 2022 08:53:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 31FB86B0078; Mon, 16 May 2022 08:53:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 034CF6B0073; Mon, 16 May 2022 08:53:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id DBA446B0072 for ; Mon, 16 May 2022 08:53:47 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 8D66C32C9D for ; Mon, 16 May 2022 12:53:47 +0000 (UTC) X-FDA: 79471598094.14.00EC4D5 Received: from mail-wm1-f43.google.com (mail-wm1-f43.google.com [209.85.128.43]) by imf11.hostedemail.com (Postfix) with ESMTP id 64072400CA for ; Mon, 16 May 2022 12:53:41 +0000 (UTC) Received: by mail-wm1-f43.google.com with SMTP id k126so8643987wme.2 for ; Mon, 16 May 2022 05:53:46 -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=1zMWiBKrxJRt4dm7AECg/jq1FaXgoQHTOEXoqP7ndjs=; b=mZvVdyV4R2NcvGq9PkFdJMQvHTRv8eCR1cvl/UDrc9cP/TP6x0tncRCcBuir+2FIdK ZxTdX/iI8L9vq2skwvMtr/gCeUCuGpaAuhNu6q5UvR9CSxtwi99hwLYDmkxcHe00t6ew 6Zlr/N+Ko8pCvL44oTBUHUbtvTel3xc3XVycs6ybFhIZTQtMLHry6Ehj8oSBsjUKEMg5 20Taq3qqMX3qqjoT18hnG05xQ0gVV/pttQErniIEaCnO/+DXYisblcvK+B/0Gi+6BRCa KZSCqQcW8MKFlWmybnuiVfeSrIkjVcaMrgVTl1uSSL9UGZUDcC827xITl6iJcZaVSe+9 oU2w== 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=1zMWiBKrxJRt4dm7AECg/jq1FaXgoQHTOEXoqP7ndjs=; b=UvZI/HPcl0MSU9uD3UrAAe9a38Yfweu70pMCKW4uhNO86YbIMb88sLrLdknNpUgGoi 4v7abMcD7Qixv9482IlrPViUNONXd5eoM6wTux37+a+bu65y9dasxPknaAKFhU1H0JtS MTYFT0ZpYwBKg6wfkDGfTVuzM4PN1WMvPfrVnSD4ktvwo+app4SUnMF4AcdLvjyu3tO9 aMCResZn/ixkkjTG9bIgAIgOeQG0qzNCS8PV1Y40y5M1qFlIWb+vYd/QLx4+HmpGvlyX +RkQGCRpqnSWfVOV+U9g8DxRpQhAgz+S7zFYnZWwPOzJ0+Fhr8MXkMTRI2jh0GKMNC95 Mw+Q== X-Gm-Message-State: AOAM531LAg9gEdPtgRbtpKDv/JvmnxgwI8kQ5h+NjVblRxBlo2iat50x rypuQeSd1quox4F6jtyKHlQ= X-Google-Smtp-Source: ABdhPJw8lMmpeW5ADElTuWJi8C91ciKJd0nw+e53cYaNTI5gWF8KbPB3ZQGhRbb9YDktYFilc2BG8A== X-Received: by 2002:a05:600c:3d8c:b0:394:6097:9994 with SMTP id bi12-20020a05600c3d8c00b0039460979994mr26918715wmb.29.1652705625931; Mon, 16 May 2022 05:53:45 -0700 (PDT) Received: from orion.localdomain ([93.99.228.15]) by smtp.gmail.com with ESMTPSA id u23-20020a05600c00d700b003942a244ec2sm9958565wmm.7.2022.05.16.05.53.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 May 2022 05:53:45 -0700 (PDT) Received: by orion.localdomain (Postfix, from userid 1003) id 8BBBCA0E76; Mon, 16 May 2022 14:54:07 +0200 (CEST) From: =?UTF-8?q?Jakub=20Mat=C4=9Bna?= To: linux-mm@kvack.org Cc: 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, david@redhat.com, =?UTF-8?q?Jakub=20Mat=C4=9Bna?= Subject: [RFC PATCH v3 1/6] [PATCH 1/6] mm: refactor of vma_merge() Date: Mon, 16 May 2022 14:54:00 +0200 Message-Id: <20220516125405.1675-2-matenajakub@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220516125405.1675-1-matenajakub@gmail.com> References: <20220516125405.1675-1-matenajakub@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 64072400CA X-Stat-Signature: h8i8zmea6p3zkc6mncbsqnfqheaemtdc Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=mZvVdyV4; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf11.hostedemail.com: domain of matenajakub@gmail.com designates 209.85.128.43 as permitted sender) smtp.mailfrom=matenajakub@gmail.com X-Rspam-User: X-HE-Tag: 1652705621-552837 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, more understandable and suitable for tracing of successful merges that are made possible by following patches in the series. 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. Exit paths are also unified. Signed-off-by: Jakub Matěna --- mm/mmap.c | 81 +++++++++++++++++++++++++------------------------------ 1 file changed, 36 insertions(+), 45 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 3aa839f81e63..4a4611443593 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1171,7 +1171,9 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, { pgoff_t pglen = (end - addr) >> PAGE_SHIFT; struct vm_area_struct *area, *next; - int err; + int err = -1; + bool merge_prev = false; + bool merge_next = false; /* * We later require that vma->vm_flags == vm_flags, @@ -1190,66 +1192,55 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, VM_WARN_ON(area && end > area->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; + area = prev; } - - /* - * 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); + } else if (merge_prev) { /* cases 2, 5, 7 */ + err = __vma_adjust(prev, prev->vm_start, + end, prev->vm_pgoff, NULL, 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 */ + 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; + next->vm_pgoff - pglen, NULL, next); + /* + * In case 3 and 4 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; } - return NULL; + /* + * Cannot merge with predecessor or successor or error in __vma_adjust? + */ + if (err) + return NULL; + khugepaged_enter_vma_merge(area, vm_flags); + return area; } /* -- 2.35.1