On 4/16/20 5:15 AM, Claudio Imbrenda wrote: >> I assumed that this was all anonymous-only so it's always dirty before >> writeback starts. > it could also be mmapped Let's say you have a mmap()'d ramfs file. Another process calls which doesn't have it mapped calls sys_write() and writes to the file. This means that host host has to write to the physical page and must do arch_make_page_accessible() in the sys_write() path somewhere. There is a get_user_pages() in that path, but it's on the _source_ buffer, not the ramfs page because the ramfs page is not mapped. There's also no __test_set_page_writeback() because you can't write back ramfs. Where is the arch_make_page_accessible() in this case on the ramfs page?
