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 <kirill.shutemov@xxxxxxxxxxxxxxx>
> Reported-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> ---
> 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" <kirill.shutemov@xxxxxxxxxxxxxxx>
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 <kirill.shutemov@xxxxxxxxxxxxxxx>
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
--
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>