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[2003:cb:c715:3f00:7545:deb6:f2f4:27ef]) by smtp.gmail.com with ESMTPSA id q9-20020a1ce909000000b003ee20b4b2dasm15205166wmc.46.2023.04.18.08.55.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Apr 2023 08:55:49 -0700 (PDT) Message-ID: <7fabe6ee-ba8f-6c48-c9f7-90982e2e258c@redhat.com> Date: Tue, 18 Apr 2023 17:55:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v4 4/6] io_uring: rsrc: avoid use of vmas parameter in pin_user_pages() Content-Language: en-US To: Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Cc: Matthew Wilcox , Jens Axboe , Pavel Begunkov , io-uring@vger.kernel.org References: <956f4fc2204f23e4c00e9602ded80cb4e7b5df9b.1681831798.git.lstoakes@gmail.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <956f4fc2204f23e4c00e9602ded80cb4e7b5df9b.1681831798.git.lstoakes@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18.04.23 17:49, Lorenzo Stoakes wrote: > We are shortly to remove pin_user_pages(), and instead perform the required > VMA checks ourselves. In most cases there will be a single VMA so this > should caues no undue impact on an already slow path. > > Doing this eliminates the one instance of vmas being used by > pin_user_pages(). > > Suggested-by: Matthew Wilcox (Oracle) > Signed-off-by: Lorenzo Stoakes > --- > io_uring/rsrc.c | 55 ++++++++++++++++++++++++++++--------------------- > 1 file changed, 31 insertions(+), 24 deletions(-) > > diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c > index 7a43aed8e395..3a927df9d913 100644 > --- a/io_uring/rsrc.c > +++ b/io_uring/rsrc.c > @@ -1138,12 +1138,37 @@ static int io_buffer_account_pin(struct io_ring_ctx *ctx, struct page **pages, > return ret; > } > > +static int check_vmas_locked(unsigned long addr, unsigned long len) TBH, the whole "_locked" suffix is a bit confusing. I was wondering why you'd want to check whether the VMAs are locked ... > +{ > + struct file *file; > + VMA_ITERATOR(vmi, current->mm, addr); > + struct vm_area_struct *vma = vma_next(&vmi); > + unsigned long end = addr + len; > + > + if (WARN_ON_ONCE(!vma)) > + return -EINVAL; > + > + file = vma->vm_file; > + if (file && !is_file_hugepages(file)) > + return -EOPNOTSUPP; You'd now be rejecting vma_is_shmem() here, no? -- Thanks, David / dhildenb