On Wed, May 24, 2023 at 08:27:13AM +1000, Dave Chinner wrote: > On Fri, May 19, 2023 at 04:22:01PM +0200, Hannes Reinecke wrote: > > I'm hitting this during booting: > > [ 5.016324] <TASK> > > [ 5.030256] iomap_iter+0x11a/0x350 > > [ 5.030264] iomap_readahead+0x1eb/0x2c0 > > [ 5.030272] read_pages+0x5d/0x220 > > [ 5.030279] page_cache_ra_unbounded+0x131/0x180 > > [ 5.030284] filemap_get_pages+0xff/0x5a0 > > Why is filemap_get_pages() using unbounded readahead? Surely > readahead should be limited to reading within EOF.... It isn't using unbounded readahead; that's an artifact of this incomplete stack trace. Actual call stack: page_cache_ra_unbounded do_page_cache_ra ondemand_readahead page_cache_sync_ra page_cache_sync_readahead filemap_get_pages As you can see, do_page_cache_ra() does limit readahead to i_size. Is ractl->mapping->host the correct way to find the inode? I always get confused. > I think Christoph's code is correct. IMO, any attempt to read beyond > the end of the device should throw out a warning and return an > error, not silently return zeros. > > If readahead is trying to read beyond the end of the device, then it > really seems to me like the problem here is readahead, not the iomap > code detecting the OOB read request.... > > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx
