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[86.156.84.164]) by smtp.googlemail.com with ESMTPSA id c11-20020a7bc84b000000b003ed2384566fsm5348810wml.21.2023.04.14.16.27.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Apr 2023 16:27:48 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Cc: Matthew Wilcox , David Hildenbrand , Jens Axboe , Pavel Begunkov , io-uring@vger.kernel.org, Lorenzo Stoakes Subject: [PATCH 5/7] io_uring: rsrc: use FOLL_SAME_FILE on pin_user_pages() Date: Sat, 15 Apr 2023 00:27:45 +0100 Message-Id: <17357dec04b32593b71e4fdf3c30a346020acf98.1681508038.git.lstoakes@gmail.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Commit edd478269640 ("io_uring/rsrc: disallow multi-source reg buffers") prevents io_pin_pages() from pinning pages spanning multiple VMAs with permitted characteristics (anon/huge), requiring that all VMAs share the same vm_file. The newly introduced FOLL_SAME_FILE flag permits this to be expressed as a GUP flag rather than having to retrieve VMAs to perform the check. We then only need to perform a VMA lookup for the first VMA to assert the anon/hugepage requirement as we know the rest of the VMAs will possess the same characteristics. Doing this eliminates the one instance of vmas being used by pin_user_pages(). Signed-off-by: Lorenzo Stoakes Suggested-by: Matthew Wilcox (Oracle) --- io_uring/rsrc.c | 39 ++++++++++++++++----------------------- 1 file changed, 16 insertions(+), 23 deletions(-) diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index 7a43aed8e395..adc860bcbd4f 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -1141,9 +1141,8 @@ static int io_buffer_account_pin(struct io_ring_ctx *ctx, struct page **pages, struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages) { unsigned long start, end, nr_pages; - struct vm_area_struct **vmas = NULL; struct page **pages = NULL; - int i, pret, ret = -ENOMEM; + int pret, ret = -ENOMEM; end = (ubuf + len + PAGE_SIZE - 1) >> PAGE_SHIFT; start = ubuf >> PAGE_SHIFT; @@ -1153,31 +1152,26 @@ struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages) if (!pages) goto done; - vmas = kvmalloc_array(nr_pages, sizeof(struct vm_area_struct *), - GFP_KERNEL); - if (!vmas) - goto done; - ret = 0; mmap_read_lock(current->mm); - pret = pin_user_pages(ubuf, nr_pages, FOLL_WRITE | FOLL_LONGTERM, - pages, vmas); + + pret = pin_user_pages(ubuf, nr_pages, + FOLL_WRITE | FOLL_LONGTERM | FOLL_SAME_FILE, + pages, NULL); if (pret == nr_pages) { - struct file *file = vmas[0]->vm_file; + /* + * lookup the first VMA, we require that all VMAs in range + * maintain the same file characteristics, as enforced by + * FOLL_SAME_FILE + */ + struct vm_area_struct *vma = vma_lookup(current->mm, ubuf); + struct file *file; /* don't support file backed memory */ - for (i = 0; i < nr_pages; i++) { - if (vmas[i]->vm_file != file) { - ret = -EINVAL; - break; - } - if (!file) - continue; - if (!vma_is_shmem(vmas[i]) && !is_file_hugepages(file)) { - ret = -EOPNOTSUPP; - break; - } - } + file = vma->vm_file; + if (file && !vma_is_shmem(vma) && !is_file_hugepages(file)) + ret = -EOPNOTSUPP; + *npages = nr_pages; } else { ret = pret < 0 ? pret : -EFAULT; @@ -1194,7 +1188,6 @@ struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages) } ret = 0; done: - kvfree(vmas); if (ret < 0) { kvfree(pages); pages = ERR_PTR(ret); -- 2.40.0