On Fri 20-11-20 14:43:20, Muchun Song wrote: > We should flush work when dissolving a hugetlb page to make sure that > the hugetlb page is freed to the buddy.
Why? This explanation on its own doen't really help to understand what is the point of the patch. > > Signed-off-by: Muchun Song <[email protected]> > --- > mm/hugetlb.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index b853aacd5c16..9aad0b63d369 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1328,6 +1328,12 @@ static void update_hpage_vmemmap_workfn(struct > work_struct *work) > } > static DECLARE_WORK(hpage_update_work, update_hpage_vmemmap_workfn); > > +static inline void flush_hpage_update_work(struct hstate *h) > +{ > + if (free_vmemmap_pages_per_hpage(h)) > + flush_work(&hpage_update_work); > +} > + > static inline void __update_and_free_page(struct hstate *h, struct page > *page) > { > /* No need to allocate vmemmap pages */ > @@ -1928,6 +1934,7 @@ static int free_pool_huge_page(struct hstate *h, > nodemask_t *nodes_allowed, > int dissolve_free_huge_page(struct page *page) > { > int rc = -EBUSY; > + struct hstate *h = NULL; > > /* Not to disrupt normal path by vainly holding hugetlb_lock */ > if (!PageHuge(page)) > @@ -1941,8 +1948,9 @@ int dissolve_free_huge_page(struct page *page) > > if (!page_count(page)) { > struct page *head = compound_head(page); > - struct hstate *h = page_hstate(head); > int nid = page_to_nid(head); > + > + h = page_hstate(head); > if (h->free_huge_pages - h->resv_huge_pages == 0) > goto out; > > @@ -1956,6 +1964,14 @@ int dissolve_free_huge_page(struct page *page) > } > out: > spin_unlock(&hugetlb_lock); > + > + /* > + * We should flush work before return to make sure that > + * the HugeTLB page is freed to the buddy. > + */ > + if (!rc && h) > + flush_hpage_update_work(h); > + > return rc; > } > > -- > 2.11.0 -- Michal Hocko SUSE Labs
