From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f51.google.com (mail-wr1-f51.google.com [209.85.221.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DFD256FC6 for ; Wed, 15 Mar 2023 20:10:07 +0000 (UTC) Received: by mail-wr1-f51.google.com with SMTP id q16so18399022wrw.2 for ; Wed, 15 Mar 2023 13:10:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1678911006; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=PjNFc/1sMZOGefBpFSEuqAcOT+g79OJ+uWo9eDYsxwg=; b=U04MlTlTCuZLzLmil7UNgqN++w9Yx1ypk+Hb8RZxgFRrUTMtmferA0mFwHFc0Yddib Sey4M7QJ8/nbJPj3Fsdhlu7LNKNXazlc7KLQPNzwQo/dHoLJK++E4FdKCW25yQcT7wL0 9MRdYCAG5gENid8qwX9yh3XW9JgcSnGD8+7uW3h1Lq5Wc5NSeIO0mCnDAFeeFfcZmhUv XvAxGtXWZ6neYXJdh9/8irHIVE4FeVkGFANuLYPAZxnX6Lr4zS79YDNDKZOxnMdHaNKs TL1o2i7jIV7BLCWmRzEshailuKHjII/KnRDx/ZDJ4XZDS0P/Zu8HM3C6fZTn7ibwiuGm l1hQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678911006; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=PjNFc/1sMZOGefBpFSEuqAcOT+g79OJ+uWo9eDYsxwg=; b=LSoXmXMhKBEPXsgsx3fZFAMPunNaJwgz3qrnkp+For+mX+PY01uKXmdfg1UnmcjzEQ gVSdfucZRGSkAnZm4t5AscgsiLAvTPzxvbxIGgDvZ13eY9mLdU0M+ZmHdkVomjTod0Rv pbS0gzQcSCOvV7vvwYP2DY3lWM16M48Est/vHX/wnEeC6OPha4IQyUg+UmuRkm2K73v3 jWFAXRP1xqxfSNzyIrSco8sa9jQ91JB7h7mAg+wpu7mkJx4MRtHizrFiqygE23SwnPlE pd/T0irHzLpwoum/2NKN5xF5/t06Ylqcxkr4TP7y16NZAH4WKK+4Ega/+rEFqxZGk6Ff dANA== X-Gm-Message-State: AO0yUKUmw4mPCDCTgthD/EBnfJEOAl3bAbstIV3anSAUDYhoD497ivtj C/ZW1H43nKLgjk9Y26cz9es= X-Google-Smtp-Source: AK7set/iDb0oAA8W1jHGhwWNaz0h3L+QskK8ZyvbCMZTalMSsRvQCWrk0wnuSpsMMK+XXUx+r1vbUw== X-Received: by 2002:a5d:4577:0:b0:2ce:a7da:ed5b with SMTP id a23-20020a5d4577000000b002cea7daed5bmr2852784wrc.47.1678911006119; Wed, 15 Mar 2023 13:10:06 -0700 (PDT) Received: from localhost (host86-146-209-214.range86-146.btcentralplus.com. [86.146.209.214]) by smtp.gmail.com with ESMTPSA id o3-20020a056000010300b002ceac2ccc4asm5567757wrx.23.2023.03.15.13.10.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Mar 2023 13:10:05 -0700 (PDT) Date: Wed, 15 Mar 2023 20:10:04 +0000 From: Lorenzo Stoakes To: Vlastimil Babka Cc: Andrew Morton , "Liam R. Howlett" , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, maple-tree@lists.infradead.org Subject: Re: [PATCH 05/10] mm/mmap/vma_merge: initialize mid and next in natural order Message-ID: References: <20230309111258.24079-1-vbabka@suse.cz> <20230309111258.24079-6-vbabka@suse.cz> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230309111258.24079-6-vbabka@suse.cz> On Thu, Mar 09, 2023 at 12:12:53PM +0100, Vlastimil Babka wrote: > It is more intuitive to go from prev to mid and then next. No functional > change. > > Signed-off-by: Vlastimil Babka > --- > mm/mmap.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 420d6847c94c..be60b344e4b1 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -912,10 +912,11 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, > if (vm_flags & VM_SPECIAL) > return NULL; > > - next = find_vma(mm, prev ? prev->vm_end : 0); > - mid = next; > - if (next && next->vm_end == end) /* cases 6, 7, 8 */ > - next = find_vma(mm, next->vm_end); > + mid = find_vma(mm, prev ? prev->vm_end : 0); > + if (mid && mid->vm_end == end) /* cases 6, 7, 8 */ > + next = find_vma(mm, mid->vm_end); > + else > + next = mid; It feels like the original implementation may have been backwards like this just to avoid this else branch. Which is silly. > > /* verify some invariant that must be enforced by the caller */ > VM_WARN_ON(prev && addr <= prev->vm_start); > -- > 2.39.2 > Reviewed-by: Lorenzo Stoakes