[PATCH v2 01/10] thp: huge zero page: basic preparation
From: Kirill A. Shutemov <hidden>
Date: 2012-09-10 13:13:25
Also in:
lkml
Subsystem:
memory management, memory management - thp (transparent huge page), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Lorenzo Stoakes, Linus Torvalds
From: "Kirill A. Shutemov" <redacted>
For now let's allocate the page on hugepage_init(). We'll switch to lazy
allocation later.
We are not going to map the huge zero page until we can handle it
properly on all code paths.
is_huge_zero_{pfn,pmd}() functions will be used by following patches to
check whether the pfn/pmd is huge zero page.
Signed-off-by: Kirill A. Shutemov <redacted>
---
mm/huge_memory.c | 29 +++++++++++++++++++++++++++++
1 files changed, 29 insertions(+), 0 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 57c4b93..88e0a7a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -46,6 +46,7 @@ static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; /* during fragmentation poll the hugepage allocator once every minute */ static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; static struct task_struct *khugepaged_thread __read_mostly; +static unsigned long huge_zero_pfn __read_mostly; static DEFINE_MUTEX(khugepaged_mutex); static DEFINE_SPINLOCK(khugepaged_mm_lock); static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
@@ -167,6 +168,28 @@ out: return err; } +static int init_huge_zero_page(void) +{ + struct page *hpage; + + hpage = alloc_pages(GFP_TRANSHUGE | __GFP_ZERO, HPAGE_PMD_ORDER); + if (!hpage) + return -ENOMEM; + + huge_zero_pfn = page_to_pfn(hpage); + return 0; +} + +static inline bool is_huge_zero_pfn(unsigned long pfn) +{ + return pfn == huge_zero_pfn; +} + +static inline bool is_huge_zero_pmd(pmd_t pmd) +{ + return is_huge_zero_pfn(pmd_pfn(pmd)); +} + #ifdef CONFIG_SYSFS static ssize_t double_flag_show(struct kobject *kobj,
@@ -550,6 +573,10 @@ static int __init hugepage_init(void) if (err) return err; + err = init_huge_zero_page(); + if (err) + goto out; + err = khugepaged_slab_init(); if (err) goto out;
@@ -574,6 +601,8 @@ static int __init hugepage_init(void) return 0; out: + if (huge_zero_pfn) + __free_page(pfn_to_page(huge_zero_pfn)); hugepage_exit_sysfs(hugepage_kobj); return err; }
--
1.7.7.6
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