diff options
Diffstat (limited to 'mm/page_counter.c')
| -rw-r--r-- | mm/page_counter.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/mm/page_counter.c b/mm/page_counter.c index 41937c9a9d11..a5ff4cbc355a 100644 --- a/mm/page_counter.c +++ b/mm/page_counter.c @@ -13,6 +13,28 @@ #include <linux/bug.h> #include <asm/page.h> +static void propagate_low_usage(struct page_counter *c, unsigned long usage) +{ + unsigned long low_usage, old; + long delta; + + if (!c->parent) + return; + + if (!c->low && !atomic_long_read(&c->low_usage)) + return; + + if (usage <= c->low) + low_usage = usage; + else + low_usage = 0; + + old = atomic_long_xchg(&c->low_usage, low_usage); + delta = low_usage - old; + if (delta) + atomic_long_add(delta, &c->parent->children_low_usage); +} + /** * page_counter_cancel - take pages out of the local counter * @counter: counter @@ -23,6 +45,7 @@ void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages) long new; new = atomic_long_sub_return(nr_pages, &counter->usage); + propagate_low_usage(counter, new); /* More uncharges than charges? */ WARN_ON_ONCE(new < 0); } @@ -42,6 +65,7 @@ void page_counter_charge(struct page_counter *counter, unsigned long nr_pages) long new; new = atomic_long_add_return(nr_pages, &c->usage); + propagate_low_usage(counter, new); /* * This is indeed racy, but we can live with some * inaccuracy in the watermark. @@ -85,6 +109,7 @@ bool page_counter_try_charge(struct page_counter *counter, new = atomic_long_add_return(nr_pages, &c->usage); if (new > c->max) { atomic_long_sub(nr_pages, &c->usage); + propagate_low_usage(counter, new); /* * This is racy, but we can live with some * inaccuracy in the failcnt. @@ -93,6 +118,7 @@ bool page_counter_try_charge(struct page_counter *counter, *fail = c; goto failed; } + propagate_low_usage(counter, new); /* * Just like with failcnt, we can live with some * inaccuracy in the watermark. @@ -165,6 +191,23 @@ int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages) } /** + * page_counter_set_low - set the amount of protected memory + * @counter: counter + * @nr_pages: value to set + * + * The caller must serialize invocations on the same counter. + */ +void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages) +{ + struct page_counter *c; + + counter->low = nr_pages; + + for (c = counter; c; c = c->parent) + propagate_low_usage(c, atomic_long_read(&c->usage)); +} + +/** * page_counter_memparse - memparse() for page counter limits * @buf: string to parse * @max: string meaning maximum possible value |