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 404A1C433F5 for ; Fri, 18 Feb 2022 12:21:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235142AbiBRMWE (ORCPT ); Fri, 18 Feb 2022 07:22:04 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:48818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235113AbiBRMVz (ORCPT ); Fri, 18 Feb 2022 07:21:55 -0500 Received: from mail-ed1-x52f.google.com (mail-ed1-x52f.google.com [IPv6:2a00:1450:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1192519C1B for ; Fri, 18 Feb 2022 04:21:39 -0800 (PST) Received: by mail-ed1-x52f.google.com with SMTP id c6so12429728edk.12 for ; Fri, 18 Feb 2022 04:21:38 -0800 (PST) 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=hmEc5DoCLSD2DUJvNGydFX4svqDfjOrJL7x2lrpSPLk=; b=CcKCLBaPT80Z0Ha52pupsWCnMFYXy7bgQULIdXfwDMH9jGcQoTvbLhQ9wMsEkGrUgP y5KLlTAyZVa/I6W8kzmGg5ctllfTE795LOkwk/yBXxnqUVyaEbEwS0TyMmmmF/bApkW3 JqfgOlbiYOuaouOsfd7tW1W4NndVQAwtd4xCYdp86nQ5J2uaX7Jh1226vYXxGmdRXCno SD/1NEm9WtU8Ex1H1w902lw0xa8IGuYrYaMM1hVIqutF7UM17ahpcD6BNJFHMqHf1x0z egOQh3b2d/znJRXCmaxrTdCwxJRY/z8W8f3FSvwpPrQuoQf57cpnENtcKT5nIkvJ6F21 1xTA== 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=hmEc5DoCLSD2DUJvNGydFX4svqDfjOrJL7x2lrpSPLk=; b=jy7CY58gIJyFxtZbqh7nDPTBBLX50NN2+jn7XCKNz8/nhRypKRrbK9MaI4WHXyL8Tz u3VigwiXp/9rsCBCZbdSgNjxhM3ZGXYfMmybMeBVv/UOjNn4U5WvA9RsB50wEp5+kO+4 4rZDJzx+noeiqeuiu9jr0Fi7n02hCeG6HITWM99QSo+H0in1WODTBSd1tmr5Fq4EUntv SDnvd5ME656diIhMOZNbnDBSKl/8eFtO+fAAJ6Ym/NTiEffTtM5I6E0At/hP+Tb3UKyC guzbBrzR2JvUGBbyasj6egvunfJ04TAdOjyD+F7SN82iekaaNjOUgpYskP6cQrNj6Mr+ u66A== X-Gm-Message-State: AOAM532hqcEpliLUrTYla8nvH5tRx7ljrzTr2WIegyqlmylnOgufVhDc JeTcYbx9Ij/BaGLwDkPn5Rs= X-Google-Smtp-Source: ABdhPJwVNqS56OqHGXAdnjOIi2ZizE0j3EbD6E/PqQm5nKLAxCraATH7mQWAOpRduhttWtSq1TRS0g== X-Received: by 2002:a50:9b12:0:b0:410:b926:d2d3 with SMTP id o18-20020a509b12000000b00410b926d2d3mr7850271edi.331.1645186897584; Fri, 18 Feb 2022 04:21:37 -0800 (PST) Received: from orion.localdomain ([93.99.228.15]) by smtp.gmail.com with ESMTPSA id 1sm2270586ejm.173.2022.02.18.04.21.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Feb 2022 04:21:35 -0800 (PST) Received: by orion.localdomain (Postfix, from userid 1003) id 435F3A7FF0; Fri, 18 Feb 2022 13:20:44 +0100 (CET) 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, =?UTF-8?q?Jakub=20Mat=C4=9Bna?= Subject: [RFC PATCH 1/4] [PATCH 1/4] mm: refactor of vma_merge() Date: Fri, 18 Feb 2022 13:20:16 +0100 Message-Id: <20220218122019.130274-2-matenajakub@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220218122019.130274-1-matenajakub@gmail.com> References: <20220218122019.130274-1-matenajakub@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Refactor vma_merge() to make it shorter, more understandable and suitable for tracing of successful merges made possible by following patches in the series. Signed-off-by: Jakub Matěna --- mm/mmap.c | 81 +++++++++++++++++++++++++++---------------------------- 1 file changed, 39 insertions(+), 42 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 1e8fdb0b51ed..b55e11f20571 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1172,6 +1172,9 @@ 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 merge_prev = 0; + int merge_both = 0; + int merge_next = 0; /* * We later require that vma->vm_flags == vm_flags, @@ -1191,65 +1194,59 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, VM_WARN_ON(addr >= end); /* - * Can it merge with the predecessor? + * Can we merge 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 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)) { + anon_vma, file, pgoff+pglen, + vm_userfaultfd_ctx, anon_name)) { + merge_next = true; + } + /* + * Can we merge both predecessor and successor? + */ + if (merge_prev && merge_next) + merge_both = is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL); + + if (merge_both) { /* cases 1, 6 */ + err = __vma_adjust(prev, prev->vm_start, + next->vm_end, prev->vm_pgoff, NULL, + prev); + area = prev; + } else if (merge_prev) { /* cases 2, 5, 7 */ + err = __vma_adjust(prev, prev->vm_start, + end, prev->vm_pgoff, NULL, prev); + area = 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); + area = next; + } else { + err = -1; } - 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; } /* -- 2.34.1