On Wed 06-11-19 14:45:43, Robert Stupp wrote: > On Wed, 2019-11-06 at 13:03 +0100, Jan Kara wrote: > > On Tue 05-11-19 13:22:11, Johannes Weiner wrote: > > > What I don't quite understand yet is why the fault path doesn't > > > make > > > progress eventually. We must drop the mmap_sem without changing the > > > state in any way. How can we keep looping on the same page? > > > > That may be a slight suboptimality with Josef's patches. If the page > > is marked as PageReadahead, we always drop mmap_sem if we can and > > start > > readahead without checking whether that makes sense or not in > > do_async_mmap_readahead(). OTOH page_cache_async_readahead() then > > clears > > PageReadahead so the only way how I can see we could loop like this > > is when > > file->ra->ra_pages is 0. Not sure if that's what's happening through. > > We'd > > need to find which of the paths in filemap_fault() calls > > maybe_unlock_mmap_for_io() to tell more. > > Yes, ra_pages==0 OK, thanks for confirmation! > 5637e22a2000-5637e22a3000 r--p 00000000 103:02 49172550 /home/snazy/devel/misc/zzz/test What kind of device & fs does your /home stay on? I don't recognize the major number... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
