On Thu 07-01-21 11:11:41, Muchun Song wrote: > On Thu, Jan 7, 2021 at 1:07 AM Michal Hocko <mhocko@xxxxxxxx> wrote: > > > > On Wed 06-01-21 16:47:37, Muchun Song wrote: > > > When dissolve_free_huge_page() races with __free_huge_page(), we can > > > do a retry. Because the race window is small. > > > > Is this a bug fix or mere optimization. I have hard time to tell from > > the description. > > It is optimization. Thanks. > > > > > > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> > > > --- > > > mm/hugetlb.c | 26 +++++++++++++++++++++----- > > > 1 file changed, 21 insertions(+), 5 deletions(-) > > > > > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > > [...] > > > @@ -1825,6 +1828,14 @@ int dissolve_free_huge_page(struct page *page) > > > } > > > out: > > > spin_unlock(&hugetlb_lock); > > > + > > > + /* > > > + * If the freeing of the HugeTLB page is put on a work queue, we should > > > + * flush the work before retrying. > > > + */ > > > + if (unlikely(rc == -EAGAIN)) > > > + flush_work(&free_hpage_work); > > > > Is it safe to wait for the work to finish from this context? > > Yes. It is safe. Please expand on why in the changelog. Same for the optimization including some numbers showing it really helps. -- Michal Hocko SUSE Labs
