From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Date: Fri, 18 Feb 2022 01:03:13 -0500 Subject: [Cluster-devel] [REPORT] kernel BUG at fs/ext4/inode.c:2620 - page_buffers() In-Reply-To: References: Message-ID: List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, Feb 18, 2022 at 04:24:20AM +0000, Matthew Wilcox wrote: > On Thu, Feb 17, 2022 at 09:54:30PM -0500, Theodore Ts'o wrote: > > process_vm_writev() uses [un]pin_user_pages_remote() which is the same > > interface uses for RDMA. But it's not clear this is ever supposed to > > work for memory which is mmap'ed region backed by a file. > > pin_user_pages_remote() appears to assume that it is an anonymous > > region, since the get_user_pages functions in mm/gup.c don't call > > read_page() to read data into any pages that might not be mmaped in. > > ... it doesn't end up calling handle_mm_fault() in faultin_page()? Ah yes, sorry, I missed that. This is what happens when a syzbot bug is thrown to a file system developer, who then has to wade theough mm code for which he is not understand.... - Ted