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
