From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-mm@kvack.org
Cc: Andi Kleen <ak@linux.intel.com>,
"H. Peter Anvin" <hpa@linux.intel.com>,
linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill@shutemov.name>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH, RFC 9/9] thp: lazy huge zero page allocation
Date: Thu, 9 Aug 2012 12:08:20 +0300 [thread overview]
Message-ID: <1344503300-9507-10-git-send-email-kirill.shutemov@linux.intel.com> (raw)
In-Reply-To: <1344503300-9507-1-git-send-email-kirill.shutemov@linux.intel.com>
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Instead of allocating huge zero page on hugepage_init() we can postpone it
until first huge zero page map. It saves memory if THP is not in use.
cmpxchg() is used to avoid race on huge_zero_pfn initialization.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/huge_memory.c | 20 ++++++++++----------
1 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3a78677..6861230 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -168,21 +168,23 @@ out:
return err;
}
-static int init_huge_zero_page(void)
+static int init_huge_zero_pfn(void)
{
struct page *hpage;
+ unsigned long pfn;
hpage = alloc_pages(GFP_TRANSHUGE | __GFP_ZERO, HPAGE_PMD_ORDER);
if (!hpage)
return -ENOMEM;
-
- huge_zero_pfn = page_to_pfn(hpage);
+ pfn = page_to_pfn(hpage);
+ if (cmpxchg(&huge_zero_pfn, 0, pfn))
+ __free_page(hpage);
return 0;
}
static inline bool is_huge_zero_pfn(unsigned long pfn)
{
- return pfn == huge_zero_pfn;
+ return huge_zero_pfn && pfn == huge_zero_pfn;
}
static inline bool is_huge_zero_pmd(pmd_t pmd)
@@ -573,10 +575,6 @@ 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;
@@ -601,8 +599,6 @@ 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;
}
@@ -752,6 +748,10 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
return VM_FAULT_OOM;
if (!(flags & FAULT_FLAG_WRITE)) {
pgtable_t pgtable;
+ if (unlikely(!huge_zero_pfn && init_huge_zero_pfn())) {
+ count_vm_event(THP_FAULT_FALLBACK);
+ goto out;
+ }
pgtable = pte_alloc_one(mm, haddr);
if (unlikely(!pgtable))
goto out;
--
1.7.7.6
next prev parent reply other threads:[~2012-08-09 9:09 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-09 9:08 [PATCH, RFC 0/9] Introduce huge zero page Kirill A. Shutemov
2012-08-09 9:08 ` [PATCH, RFC 1/9] thp: huge zero page: basic preparation Kirill A. Shutemov
2012-08-09 9:08 ` [PATCH, RFC 2/9] thp: zap_huge_pmd(): zap huge zero pmd Kirill A. Shutemov
2012-08-09 9:08 ` [PATCH, RFC 3/9] thp: copy_huge_pmd(): copy huge zero page Kirill A. Shutemov
2012-08-09 9:08 ` [PATCH, RFC 4/9] thp: do_huge_pmd_wp_page(): handle " Kirill A. Shutemov
2012-08-09 9:08 ` [PATCH, RFC 5/9] thp: change_huge_pmd(): keep huge zero page write-protected Kirill A. Shutemov
2012-08-09 9:08 ` [PATCH, RFC 6/9] thp: add address parameter to split_huge_page_pmd() Kirill A. Shutemov
2012-08-16 19:42 ` Andrea Arcangeli
2012-08-17 7:49 ` Kirill A. Shutemov
2012-08-09 9:08 ` [PATCH, RFC 7/9] thp: implement splitting pmd for huge zero page Kirill A. Shutemov
2012-08-16 19:27 ` Andrea Arcangeli
2012-08-17 8:12 ` Kirill A. Shutemov
2012-08-17 16:33 ` Andrea Arcangeli
2012-08-31 14:06 ` Kirill A. Shutemov
2012-08-09 9:08 ` [PATCH, RFC 8/9] thp: setup huge zero page on non-write page fault Kirill A. Shutemov
2012-08-09 9:08 ` Kirill A. Shutemov [this message]
[not found] ` <20120810034912.GA31071@hacker.(null)>
2012-08-10 10:33 ` [PATCH, RFC 0/9] Introduce huge zero page Kirill A. Shutemov
2012-08-16 19:20 ` Andrew Morton
2012-08-16 19:40 ` Andrea Arcangeli
2012-08-16 23:08 ` H. Peter Anvin
2012-08-16 23:12 ` Andi Kleen
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