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[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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230309111258.24079-6-vbabka@suse.cz> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: BE80E80012 X-Stat-Signature: wyefu8fjkpjcniw9cxwfsiu3uktzfc9w X-HE-Tag: 1678911007-776391 X-HE-Meta: U2FsdGVkX1+t21VLRtuHbW1UPQxrP0RiFib7OmJyO0WcFiFl6j+PtCpqgC++kiix8ixGS7xHBjg8UXYJ4+QczNKgPWBhdtd5n506lIXoXbGbI7pWyiuz26ADvW7LKgTCa15jq8ajMk/TX/2k+vXQ3f8w5YiNb4jTLl++EqkC5KwwTlCq+eCBaEaqtlOd9ynuNl1rm7mH5JR12Vgzq1GWhOlXjwkCjVVmfcOi79orfOFNpHdu9BmV7c2hlGZ9fh8DTjfk6KuNYSe5e6X/FVBVued9x9fC0mObTP4zQkocrZ0XmQEAIOglt9UL6Z2Iumc3LWvlPv/9Y+d+yHUqCrb48OzOKdF32P8B4RviIMNeOMkC3u46igazu4Ai9XjInjDP1ucXDM3BuVR1lMToW/JdXpmn6ez90fjA4JB+InLObqGdV5qyamXn0X7MRDgmeWtBbybUE0nCVjdgCGiPVKyigrJSFJ8K53tZA/yJrCV5y143w4HD+zx97Ro/uWBTVaxFa8BGUYq1AyLMNjFmiOeIw6gQrewa3PGojMW8Cy/rgaX9vHGq3XGY8OkAt18NPia6TclMYtAkUvZlVwTGtaN9E5zGohcsavU6uqL9SDUaopWQCKG4+OOide3d3sJBU8BZSKRD3lxLbg++NDh9FqpeAxZTJSvCxqvOAp356hr/Pqhxc6WGH2+HY0nQkXmlgCa1ARhET4uH4DRZ/gUB2IfcO6GRWQNVsszqsou/Ch+NjwT3TsILG4riG0SR1M2n1/UvmR4rYJHtXCJ7IaPAoUOOVABgyL41sKp+3gGWtyrwklxucwBqExWfJvPGFQAOGv/fcrugId2fHeFTdawr6b2410XHJwb4Vce1YuDM8bl36dNGMg/eSgTHR5uI7brormguqEJzbmsSpCvbahwKrw8lpslQebNr072SSXJbccHZl/qDXpGbPqkxw3U2rkMyBFUScUWEs5wjDZpdWvvZ9wO C5qF34wE +ADwviilGsEcILzxBYg7e6gvjhcyrBJdXBkCR+h3HSBD9wAA/cD4y7DfS208S1qyP9gltoY9rfLFStUWoAAk+IfbSLK6Ru9O0WFe7fW2Sc+IMZOVl3ptPhIyh+Zb9TZ/1EkIJgy7/bnU0dPAc08LOydHj2Sfa/AKAtPuIEtHa3c0wf/OGF1k5NnAQK30FVqhc/R1sqcT8oFGvnNJ8P3NI4PVaPu5zZVHJWkcSiqLSs9PH3rTB8VyFxgqedNJiksJN3gMCbKbQCkuuz91oSlTxxZUc9S0lMwKahEgbUcWXencZ1oFNsFjB0tvYFRQVEDVrXwq4b8rasDKqlN8sLkRx9ngJpocSVnq3siTf6AybOlluy4jINQhHDXgkljbDOROekIEqiWs5P5jQQDXmL4gzn797Z1u/zfnUzJbb67oPBbde7D+8upxOYS08pNR3HK9s7SZ46a4K2cdtfDGzJpEF5yzjIP1UGmzYKv8w 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: 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