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Registered in England and Wales under Company Registration No. 3798903 From: David Howells To: Jens Axboe , Matthew Wilcox , Miklos Szeredi , Amit Shah cc: dhowells@redhat.com, linux-fsdevel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC][PATCH v2] splice: Prevent gifting of multipage folios MIME-Version: 1.0 Content-ID: <2740800.1677513063.1@warthog.procyon.org.uk> Date: Mon, 27 Feb 2023 15:51:03 +0000 Message-ID: <2740801.1677513063@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: C92ACC0018 X-Stat-Signature: ocmtse3q3ahnsa9dbhrndrp6p7yhuo3d X-Rspam-User: X-HE-Tag: 1677513069-578929 X-HE-Meta: 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 h5YoX8Vv diqPOf9/cik9DyBtPNeuslRlwqUV4xAvtrS5o/8qKQa3ZSTR0iEFyWMs9D4EIBlcfu/9MWtPWLMSyRIPzeo99cC1Jj2N83HG/A6kLxvqNuHjyDP86i4kBdVQ1ElWAdHBWUUJsZh5NKz2C/snnBMO0VSnGYA6llZRXfDgbxks5MMSdCSOnRU/ayNtP9kehjyqU9g029OIj8KgprlXirEIy+uGAym2Cy1MB9eKd6ppie3IH9grW+errD9zponX/G8m7c6ll+4xTnFbVDML4mYsgX2eY1LROuiiBVqhnDD3mTv00fQeo/kNGHLYqtjFVkH8e7QcJX8h8KgXRU1WePFfc+onx2WXIlx4RMd85InQJv/j6kB4RYMdt44rE3q0tUL3D3WgzUC7AAtQU3NnoziSqGVoDl3hekru6vnWd308AgkAefVM= 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: Don't let parts of compound pages/multipage folios be gifted by (vm)splice into a pipe as the other end may only be expecting single-page gifts (fuse and virtio console for example). replace_page_cache_folio(), for example, will do the wrong thing if it tries to replace a single paged folio with a multipage folio. Try to avoid this by making add_to_pipe() remove the gift flag on multipage folios. Fixes: 7afa6fd037e5 ("[PATCH] vmsplice: allow user to pass in gift pages") Signed-off-by: David Howells cc: Matthew Wilcox cc: Jens Axboe cc: Miklos Szeredi cc: Amit Shah cc: linux-fsdevel@vger.kernel.org cc: virtualization@lists.linux-foundation.org cc: linux-mm@kvack.org Reviewed-by: Matthew Wilcox (Oracle) --- fs/splice.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/splice.c b/fs/splice.c index 2e76dbb81a8f..8bbd7794d9f0 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -240,6 +240,8 @@ ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) } else if (pipe_full(head, tail, pipe->max_usage)) { ret = -EAGAIN; } else { + if (PageCompound(buf->page)) + buf->flags &= ~PIPE_BUF_FLAG_GIFT; pipe->bufs[head & mask] = *buf; pipe->head = head + 1; return buf->len;