On Mon, Aug 7, 2023 at 8:10 PM Yin Fengwei <fengwei.yin@xxxxxxxxx> wrote: > > In madvise_cold_or_pageout_pte_range() and madvise_free_pte_range(), > folio_mapcount() is used to check whether the folio is shared. But it's > not correct as folio_mapcount() returns total mapcount of large folio. > > Use folio_estimated_sharers() here as the estimated number is enough. > > > This patchset will fix the cases: > User space application call madvise() with MADV_FREE, MADV_COLD and > MADV_PAGEOUT for specific address range. There are THP mapped to the > range. Without the patchset, the THP is skipped. With the patch, the > THP will be split and handled accordingly. > > David reported the cow self test skip some cases because of > MADV_PAGEOUT skip THP: > https://lore.kernel.org/linux-mm/9e92e42d-488f-47db-ac9d-75b24cd0d037@xxxxxxxxx/T/#mbf0f2ec7fbe45da47526de1d7036183981691e81 > and I confirmed this patchset make it work again. > > > Changelog from v1: > - Avoid two Fixes tags make backport harder. Thank Andrew for pointing > this out. > > - Add note section to mention this is a temporary fix which is fine > to reduce user-visble effects. For long term fix, we should wait for > David's solution. Thank Ryan and David for pointing this out. > > - Spell user-visible effects out. Then people could decide whether > these patches are necessary for stable branch. Thank Andrew for > pointing this out. LGTM, thank you.
