On Wed, Aug 2, 2023 at 6:56 AM Yin, Fengwei <fengwei.yin@xxxxxxxxx> wrote: > > > > On 8/2/2023 8:49 PM, Ryan Roberts wrote: > > On 02/08/2023 13:42, Yin, Fengwei wrote: > >> > >> > >> On 8/2/2023 8:40 PM, Ryan Roberts wrote: > >>> On 02/08/2023 13:35, Yin, Fengwei wrote: > >>>> > >>>> > >>>> On 8/2/2023 6:27 PM, Ryan Roberts wrote: > >>>>> On 28/07/2023 17:13, Yin Fengwei 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. > >>>>>> > >>>>>> Yin Fengwei (2): > >>>>>> madvise: don't use mapcount() against large folio for sharing check > >>>>>> madvise: don't use mapcount() against large folio for sharing check > >>>>>> > >>>>>> mm/huge_memory.c | 2 +- > >>>>>> mm/madvise.c | 6 +++--- > >>>>>> 2 files changed, 4 insertions(+), 4 deletions(-) > >>>>>> > >>>>> > >>>>> As a set of fixes, I agree this is definitely an improvement, so: > >>>>> > >>>>> Reviewed-By: Ryan Roberts > >>>> Thanks. > >>>> > >>>>> > >>>>> > >>>>> But I have a couple of comments around further improvements; > >>>>> > >>>>> Once we have the scheme that David is working on to be able to provide precise > >>>>> exclusive vs shared info, we will probably want to move to that. Although that > >>>>> scheme will need access to the mm_struct of a process known to be mapping the > >>>>> folio. We have that info, but its not passed to folio_estimated_sharers() so we > >>>>> can't just reimplement folio_estimated_sharers() - we will need to rework these > >>>>> call sites again. > >>>> Yes. This could be extra work. Maybe should delay till David's work is done. > >>> > >>> What you have is definitely an improvement over what was there before. And is > >>> probably the best we can do without David's scheme. So I wouldn't delay this. > >>> Just pointing out that we will be able to make it even better later on (if > >>> David's stuff goes in). > >> Yes. I agree that we should wait for David's work ready and do fix based on that. > > > > I was suggesting the opposite - not waiting. Then we can do separate improvement > > later. > Let's wait for David's work ready. Waiting is fine as long as we don't miss the next merge window -- we don't want these two bugs to get into another release. Also I think we should cc stable, since as David mentioned, they have been causing selftest failures.
