On Tue Jun 25, 2024 at 7:44 AM EDT, Pankaj Raghav (Samsung) wrote: > From: Luis Chamberlain <mcgrof@xxxxxxxxxx> > > split_folio() and split_folio_to_list() assume order 0, to support > minorder for non-anonymous folios, we must expand these to check the > folio mapping order and use that. > > Set new_order to be at least minimum folio order if it is set in > split_huge_page_to_list() so that we can maintain minimum folio order > requirement in the page cache. > > Update the debugfs write files used for testing to ensure the order > is respected as well. We simply enforce the min order when a file > mapping is used. > > Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx> > Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx> > Reviewed-by: Hannes Reinecke <hare@xxxxxxx> > --- > There was a discussion about whether we need to consider truncation of > folio to be considered a split failure or not [1]. The new code has > retained the existing behaviour of returning a failure if the folio was > truncated. I think we need to have a separate discussion whethere or not > to consider it as a failure. <snip> > > +int split_folio_to_list(struct folio *folio, struct list_head *list) > +{ > + unsigned int min_order = 0; > + > + if (!folio_test_anon(folio)) { > + if (!folio->mapping) { > + count_vm_event(THP_SPLIT_PAGE_FAILED); Regardless this folio split is from a truncation or not, you should not count every folio split as a THP_SPLIT_PAGE_FAILED. Since not every folio is a THP. You need to do: if (folio_test_pmd_mappable(folio)) count_vm_event(THP_SPLIT_PAGE_FAILED); See commit 835c3a25aa37 ("mm: huge_memory: add the missing folio_test_pmd_mappable() for THP split statistics") > + return -EBUSY; > + } > + min_order = mapping_min_folio_order(folio->mapping); > + } > + > + return split_huge_page_to_list_to_order(&folio->page, list, min_order); > +} > + -- Best Regards, Yan, Zi
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