Hello, On Mon, Dec 05, 2016 at 09:55:10PM -0800, Hugh Dickins wrote: > Rechecking PageLRU() after get_page_unless_zero() may have value, but > holding zone_lru_lock around that serves no useful purpose: delete it. IIRC this lock/unlock was added on purpose, by request from Minchan. It serves as a barrier that guarantees that all page fields (specifically ->mapping in case of anonymous pages) have been properly initialized by the time we pass it to rmap_walk(). Here's a reference to the thread where this problem was discussed: http://lkml.kernel.org/r/<20150430082531.GD21771@blaptop> > > Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> > --- > > mm/page_idle.c | 4 ---- > 1 file changed, 4 deletions(-) > > --- 4.9-rc8/mm/page_idle.c 2016-10-02 16:24:33.000000000 -0700 > +++ linux/mm/page_idle.c 2016-12-05 19:44:32.646625435 -0800 > @@ -30,7 +30,6 @@ > static struct page *page_idle_get_page(unsigned long pfn) > { > struct page *page; > - struct zone *zone; > > if (!pfn_valid(pfn)) > return NULL; > @@ -40,13 +39,10 @@ static struct page *page_idle_get_page(u > !get_page_unless_zero(page)) > return NULL; > > - zone = page_zone(page); > - spin_lock_irq(zone_lru_lock(zone)); > if (unlikely(!PageLRU(page))) { > put_page(page); > page = NULL; > } > - spin_unlock_irq(zone_lru_lock(zone)); > return page; > } > -- 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>