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[2003:cb:c705:2600:951d:63df:c091:3b45]) by smtp.gmail.com with ESMTPSA id z2-20020adff1c2000000b0020c5253d8dcsm1536613wro.40.2022.06.01.06.37.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Jun 2022 06:37:56 -0700 (PDT) Message-ID: Date: Wed, 1 Jun 2022 15:37:55 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH 2/4] mm/shmem: return -EINVAL for addr not PAGE_SIZE aligned Content-Language: en-US To: Chen Wandun , hughd@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220601124417.2872001-1-chenwandun@huawei.com> <20220601124417.2872001-3-chenwandun@huawei.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220601124417.2872001-3-chenwandun@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01.06.22 14:44, Chen Wandun wrote: > If addr is not PAGE_SIZE aligned, return -EINVAL directly. Why is this one to be treated in a special way compared to all of the other related checks? > Besides, use macro offset_in_page to check addr is not > PAGE_SIZE aligned case. Using offset_in_page() LGTM. > > Signed-off-by: Chen Wandun > --- > mm/shmem.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 80c361c3d82c..1136dd7da9e5 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -2143,8 +2143,8 @@ unsigned long shmem_get_unmapped_area(struct file *file, > return addr; > if (IS_ERR_VALUE(addr)) > return addr; > - if (addr & ~PAGE_MASK) > - return addr; > + if (offset_in_page(addr)) > + return -EINVAL; > if (addr > TASK_SIZE - len) > return addr; > > @@ -2197,7 +2197,7 @@ unsigned long shmem_get_unmapped_area(struct file *file, > inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags); > if (IS_ERR_VALUE(inflated_addr)) > return addr; > - if (inflated_addr & ~PAGE_MASK) > + if (offset_in_page(inflated_addr)) > return addr; > > inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1); -- Thanks, David / dhildenb