On Wed 16-07-14 12:28:00, Johannes Weiner wrote: > Naoya-san reports that hugetlb pages now get charged as file cache, > which wreaks all kinds of havoc during migration, uncharge etc. > > The file-specific charge path used to filter PageCompound(), but it > wasn't commented and so it got lost when unifying the charge paths. > > We can't add PageCompound() back into a unified charge path because of > THP, so filter huge pages directly in add_to_page_cache().
This looks a bit fragile to me but I understand your motivation to not punish all the code paths with PageHuge check. > Reported-by: Naoya Horiguchi <[email protected]> > Signed-off-by: Johannes Weiner <[email protected]> Acked-by: Michal Hocko <[email protected]> > --- > mm/filemap.c | 20 ++++++++++++++------ > 1 file changed, 14 insertions(+), 6 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 114cd89c1cc2..c088ac01e856 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -31,6 +31,7 @@ > #include <linux/security.h> > #include <linux/cpuset.h> > #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */ > +#include <linux/hugetlb.h> > #include <linux/memcontrol.h> > #include <linux/cleancache.h> > #include <linux/rmap.h> > @@ -560,19 +561,24 @@ static int __add_to_page_cache_locked(struct page *page, > pgoff_t offset, gfp_t gfp_mask, > void **shadowp) > { > + int huge = PageHuge(page); > struct mem_cgroup *memcg; > int error; > > VM_BUG_ON_PAGE(!PageLocked(page), page); > VM_BUG_ON_PAGE(PageSwapBacked(page), page); > > - error = mem_cgroup_try_charge(page, current->mm, gfp_mask, &memcg); > - if (error) > - return error; > + if (!huge) { > + error = mem_cgroup_try_charge(page, current->mm, > + gfp_mask, &memcg); > + if (error) > + return error; > + } > > error = radix_tree_maybe_preload(gfp_mask & ~__GFP_HIGHMEM); > if (error) { > - mem_cgroup_cancel_charge(page, memcg); > + if (!huge) > + mem_cgroup_cancel_charge(page, memcg); > return error; > } > > @@ -587,14 +593,16 @@ static int __add_to_page_cache_locked(struct page *page, > goto err_insert; > __inc_zone_page_state(page, NR_FILE_PAGES); > spin_unlock_irq(&mapping->tree_lock); > - mem_cgroup_commit_charge(page, memcg, false); > + if (!huge) > + mem_cgroup_commit_charge(page, memcg, false); > trace_mm_filemap_add_to_page_cache(page); > return 0; > err_insert: > page->mapping = NULL; > /* Leave page->index set: truncation relies upon it */ > spin_unlock_irq(&mapping->tree_lock); > - mem_cgroup_cancel_charge(page, memcg); > + if (!huge) > + mem_cgroup_cancel_charge(page, memcg); > page_cache_release(page); > return error; > } > -- > 2.0.0 > -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
