On Thu, Jan 21, 2016 at 03:09:23PM +0300, Kirill A. Shutemov wrote: > If we have a lot of pages in queue to be split, deferred_split_scan() > can spend unreasonable amount of time under spinlock with disabled > interrupts. > > Let's cap number of pages to split on scan by sc->nr_to_scan. > > Signed-off-by: Kirill A. Shutemov <[email protected]> > Reported-by: Andrea Arcangeli <[email protected]> > --- > mm/huge_memory.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 36f98459f854..298dbc001b07 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -3478,17 +3478,19 @@ static unsigned long deferred_split_scan(struct > shrinker *shrink, > int split = 0; > > spin_lock_irqsave(&pgdata->split_queue_lock, flags); > - list_splice_init(&pgdata->split_queue, &list); > - > /* Take pin on all head pages to avoid freeing them under us */ > list_for_each_safe(pos, next, &list) {
Well, that's embarrassing... :-/ I forgot to commit one local change here. Sorry. >From 5b27991afe0e4018f2503593ade85d35ce045fbc Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" <[email protected]> Date: Thu, 4 Feb 2016 15:40:03 +0300 Subject: [PATCH] thp: get deferred_split_scan() work again We really need to iterate over split_queue, not local empty list to get anything split from the shrinker. Signed-off-by: Kirill A. Shutemov <[email protected]> Fixes: e3ae19535c66 ("thp: limit number of object to scan on deferred_split_scan()") --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 36c070167b71..08fc0ba2207e 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3482,7 +3482,7 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, spin_lock_irqsave(&pgdata->split_queue_lock, flags); /* Take pin on all head pages to avoid freeing them under us */ - list_for_each_safe(pos, next, &list) { + list_for_each_safe(pos, next, &pgdata->split_queue) { page = list_entry((void *)pos, struct page, mapping); page = compound_head(page); if (get_page_unless_zero(page)) { -- Kirill A. Shutemov
