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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id d8-20020a05600c34c800b003dc4480df80sm19719174wmq.34.2023.03.01.00.26.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Mar 2023 00:26:16 -0800 (PST) Message-ID: <98791b0f-0c00-0d0d-4831-3c36fce55888@redhat.com> Date: Wed, 1 Mar 2023 09:26:15 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH 1/2] mm/mmap: remove unnecessary vp->vma check in vma_prepare To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: sfr@canb.auug.org.au, error27@gmail.com, willy@infradead.org, Liam.Howlett@oracle.com, jgg@ziepe.ca, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, mathieu.desnoyers@efficios.com, pasha.tatashin@soleen.com, laurent.dufour@fr.ibm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel test robot References: <20230301022720.1380780-1-surenb@google.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230301022720.1380780-1-surenb@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 1776618000F X-Rspamd-Server: rspam01 X-Stat-Signature: ep5imggjzb5enb314k1tau4r8oxcgyoz X-HE-Tag: 1677659180-780424 X-HE-Meta: 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 inWKWXFC 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 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 01.03.23 03:27, Suren Baghdasaryan wrote: > vp->vma in vma_prepare() is always non-NULL, therefore checking it is > not necessary. Remove the extra check. > > Fixes: e8f071350ea5 ("mm/mmap: write-lock VMAs in vma_prepare before modifying them") > Reported-by: kernel test robot > Reported-by: Dan Carpenter It would be great to mention that this simply silences a smatch warning. Otherwise, one might be mislead that this commit fixes an actual BUG ;) > Link: https://lore.kernel.org/r/202302281802.J93Nma7q-lkp@intel.com/ > Signed-off-by: Suren Baghdasaryan > --- > Fix cleanly apply over mm-unstable, SHA in "Fixes" is from that tree. > > mm/mmap.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 0cd3714c2182..0759d53b470c 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -505,8 +505,7 @@ static inline void init_vma_prep(struct vma_prepare *vp, > */ > static inline void vma_prepare(struct vma_prepare *vp) > { > - if (vp->vma) > - vma_start_write(vp->vma); > + vma_start_write(vp->vma); > if (vp->adj_next) > vma_start_write(vp->adj_next); > /* vp->insert is always a newly created VMA, no need for locking */ Yes, that looks correct. Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb