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Sat, 15 Apr 2023 05:09:31 -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 v3 5/7] io_uring: rsrc: use FOLL_SAME_FILE on pin_user_pages() Date: Sat, 15 Apr 2023 13:09:30 +0100 Message-Id: X-Mailer: git-send-email 2.40.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 5C9834000E X-Stat-Signature: ex7mpsb13pikfskhxph7ntw9pn715iix X-HE-Tag: 1681560574-370230 X-HE-Meta: U2FsdGVkX184dMfgJJYosoiBIZzldTgQgXGIAzc/YdthvW4F1ajYDFqAs2dKzbYkikfAlIcAOflfNfg2sZmAO9A76oMJ3Of0OmQuMDh5dsTUn4Xhuzk3MQVcOqy0+4Nh1x8LdoC9vevwVc8iBEUsxnVa+seM7/e1YuUGO5AKiVBkpw09KFNpsbQRUJ3cdt5pxVTpbyZ+Cm/H7WUyYLObHnxY2BAD5vk3igy2LMbzNo4NZXHZuJ+tuzNwh5NI3YY+DIjCyUQC9W6zFhuetP5qTkXv52d7OmCNBMwU703KK57jRoQgLciUrk9M5sW1VRIIi4PIhwyzGRzQX7AJl2WzhzIvioDJYKqRVMF72Ywk9HodR+6Iy1guv2Xiq7i4zQIuEvui8c+94zClHsYT1ZGa9uYGoobJnNICVR1C6MY+OSCcNh/s4v8XMt5+vk71AkK5752QydsDlo8WXlT0kmiYypogvrYsxm7s4tWSfmzbxJ5ZIYrc0Cn3LjXd8f8la1OAtmlY+1j36JxF+QPu8/1Xo9k4C4Py50hzgyuN5GGYW/wHofQHBZfrrAVibK1o5hOtl/MF0XPLxvTnNjlm+WvOz9shiSP6hqi5G+kNE4Gob+ko11gN4xK924V+rXkZoCVeyu5Z+4XKMzfjsYDe4U9+SLtyLz4f3IJr9cepapQW5bkcyJoqh8PRYzs4GXiL/5cc/Y+bNichQQVtKewjLYcq84SXC8TjIiHW8lXtbg2NNpnixdsx6J5pOrTAcOh83ibMn+BSTeWi7guXLoajoaJB0eL8Wvpsq3Aj96TkfYQeyf7cFQU6NVDRTtod76P1kMI1LZTKwZYBt1Bur/DOdBpYINW8FlxQA5kw40IaYxKhEmqqUF5qEgt+NbZrnctW8G+G0pTe/ydWo6GRr0mzIBZ2pL/yk0qa6pUl8e/wAu1MjYp/u6aSpsVCYCZ6IDfTi06HkHhIe5Vzj5MmXtq0fzH dsLLQRp9 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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: 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 | 40 ++++++++++++++++++---------------------- 1 file changed, 18 insertions(+), 22 deletions(-) diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index 7a43aed8e395..56de4d7bfc2b 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 +1152,29 @@ 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)) { + if (WARN_ON_ONCE(!vma)) { + ret = -EINVAL; + } else { + /* don't support file backed memory */ + file = vma->vm_file; + if (file && !vma_is_shmem(vma) && !is_file_hugepages(file)) ret = -EOPNOTSUPP; - break; - } } + *npages = nr_pages; } else { ret = pret < 0 ? pret : -EFAULT; @@ -1194,7 +1191,6 @@ 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