On Wed, Jun 14, 2023 at 05:35:02PM +0200, Hannes Reinecke wrote:
> Hmm. And for that I'm hitting include/linux/pagemap.h:1250 pretty
> consistently; something's going haywire with readahead.
Is that this one?
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
in __readahead_folio()
> Matthew, are you sure that this one:
>
> /**
>
> * readahead_length - The number of bytes in this readahead request.
>
> * @rac: The readahead request.
>
> */
> static inline size_t readahead_length(struct readahead_control *rac)
> {
> return rac->_nr_pages * PAGE_SIZE;
> }
>
> is tenable for large folios?
> Especially as we have in mm/readahead.c:499
>
> ractl->_nr_pages += 1UL << order;
>
> Hmm?
Yes. nr_pages really is the number of pages.
I'm somewhat surprised you're not hitting:
VM_BUG_ON_FOLIO(index & (folio_nr_pages(folio) - 1), folio);
in __filemap_add_folio(). Maybe the filesystems in question always
access indices which are naturally aligned to the block size.
