On Thu, 31 Jul 2014 11:22:35 +0900 Gioh Kim <gioh.kim@xxxxxxx> wrote: > The previous PATCH inserts invalidate_bh_lrus() only into CMA code. > HOTPLUG needs also dropping bh of lru. > So v2 inserts invalidate_bh_lrus() into both of CMA and HOTPLUG. > > > ---------------------------- 8< ---------------------------- > The bh must be free to migrate a page at which bh is mapped. > The reference count of bh is increased when it is installed > into lru so that the bh of lru must be freed before migrating the page. > > This frees every bh of lru. We could free only bh of migrating page. > But searching lru sometimes costs more than invalidating entire lru. > > Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx> > Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx> > --- > mm/memory_hotplug.c | 1 + > mm/page_alloc.c | 2 ++ > 2 files changed, 3 insertions(+) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index a3797d3..1c5454f 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1672,6 +1672,7 @@ repeat: > lru_add_drain_all(); > cond_resched(); > drain_all_pages(); > + invalidate_bh_lrus(); Both of these calls should have a comment explaining why invalidate_bh_lrus() is being called. > } > > pfn = scan_movable_pages(start_pfn, end_pfn); > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index b99643d4..c00dedf 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6369,6 +6369,8 @@ int alloc_contig_range(unsigned long start, unsigned long end, > if (ret) > return ret; > > + invalidate_bh_lrus(); > + > ret = __alloc_contig_migrate_range(&cc, start, end); > if (ret) > goto done; I do feel that this change is likely to be beneficial, but I don't want to apply such a patch until I know what its effects are upon all alloc_contig_range() callers. Especially hugetlb. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>