Messages in this thread Patch in this message | | | From | Zi Yan <> | Subject | [RFC PATCH 21/31] mm: thp: 1GB zero page shrinker. | Date | Fri, 15 Feb 2019 14:08:46 -0800 |
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From: Zi Yan <ziy@nvidia.com>
Remove 1GB zero page when we are under memory pressure.
Signed-off-by: Zi Yan <ziy@nvidia.com> --- mm/huge_memory.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index bbdbc9ae06bf..41adc103ead1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -207,6 +207,32 @@ static struct shrinker huge_zero_page_shrinker = { .seeks = DEFAULT_SEEKS, }; +static unsigned long shrink_huge_pud_zero_page_count(struct shrinker *shrink, + struct shrink_control *sc) +{ + /* we can free zero page only if last reference remains */ + return atomic_read(&huge_pud_zero_refcount) == 1 ? HPAGE_PUD_NR : 0; +} + +static unsigned long shrink_huge_pud_zero_page_scan(struct shrinker *shrink, + struct shrink_control *sc) +{ + if (atomic_cmpxchg(&huge_pud_zero_refcount, 1, 0) == 1) { + struct page *zero_page = xchg(&huge_pud_zero_page, NULL); + BUG_ON(zero_page == NULL); + __free_pages(zero_page, compound_order(zero_page)); + return HPAGE_PUD_NR; + } + + return 0; +} + +static struct shrinker huge_pud_zero_page_shrinker = { + .count_objects = shrink_huge_pud_zero_page_count, + .scan_objects = shrink_huge_pud_zero_page_scan, + .seeks = DEFAULT_SEEKS, +}; + #ifdef CONFIG_SYSFS static ssize_t enabled_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) @@ -474,6 +500,9 @@ static int __init hugepage_init(void) err = register_shrinker(&huge_zero_page_shrinker); if (err) goto err_hzp_shrinker; + err = register_shrinker(&huge_pud_zero_page_shrinker); + if (err) + goto err_hpzp_shrinker; err = register_shrinker(&deferred_split_shrinker); if (err) goto err_split_shrinker; @@ -496,6 +525,8 @@ static int __init hugepage_init(void) err_khugepaged: unregister_shrinker(&deferred_split_shrinker); err_split_shrinker: + unregister_shrinker(&huge_pud_zero_page_shrinker); +err_hpzp_shrinker: unregister_shrinker(&huge_zero_page_shrinker); err_hzp_shrinker: khugepaged_destroy(); -- 2.20.1
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