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Date: Fri, 9 Aug 2013 01:21:41 -0400
From: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Cc: Mel Gorman <mgorman@...e.de>, Hugh Dickins <hughd@...gle.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Andi Kleen <andi@...stfloor.org>,
Hillf Danton <dhillf@...il.com>, Michal Hocko <mhocko@...e.cz>,
Rik van Riel <riel@...hat.com>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
linux-kernel@...r.kernel.org,
Naoya Horiguchi <nao.horiguchi@...il.com>
Subject: [PATCH 8/9] migrate: check movability of hugepage in unmap_and_move_huge_page()
Currently hugepage migration works well only for pmd-based hugepages
(mainly due to lack of testing,) so we had better not enable migration
of other levels of hugepages until we are ready for it.
Some users of hugepage migration (mbind, move_pages, and migrate_pages)
do page table walk and check pud/pmd_huge() there, so they are safe.
But the other users (softoffline and memory hotremove) don't do this,
so without this patch they can try to migrate unexpected types of hugepages.
To prevent this, we introduce hugepage_migration_support() as an architecture
dependent check of whether hugepage are implemented on a pmd basis or not.
And on some architecture multiple sizes of hugepages are available, so
hugepage_migration_support() also checks hugepage size.
Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
---
arch/arm/mm/hugetlbpage.c | 5 +++++
arch/arm64/mm/hugetlbpage.c | 5 +++++
arch/ia64/mm/hugetlbpage.c | 5 +++++
arch/metag/mm/hugetlbpage.c | 5 +++++
arch/mips/mm/hugetlbpage.c | 5 +++++
arch/powerpc/mm/hugetlbpage.c | 10 ++++++++++
arch/s390/mm/hugetlbpage.c | 5 +++++
arch/sh/mm/hugetlbpage.c | 5 +++++
arch/sparc/mm/hugetlbpage.c | 5 +++++
arch/tile/mm/hugetlbpage.c | 5 +++++
arch/x86/mm/hugetlbpage.c | 8 ++++++++
include/linux/hugetlb.h | 12 ++++++++++++
mm/migrate.c | 10 ++++++++++
13 files changed, 85 insertions(+)
diff --git v3.11-rc3.orig/arch/arm/mm/hugetlbpage.c v3.11-rc3/arch/arm/mm/hugetlbpage.c
index 3d1e4a2..3f3b6a7 100644
--- v3.11-rc3.orig/arch/arm/mm/hugetlbpage.c
+++ v3.11-rc3/arch/arm/mm/hugetlbpage.c
@@ -99,3 +99,8 @@ int pmd_huge(pmd_t pmd)
{
return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
}
+
+int pmd_huge_support(void)
+{
+ return 1;
+}
diff --git v3.11-rc3.orig/arch/arm64/mm/hugetlbpage.c v3.11-rc3/arch/arm64/mm/hugetlbpage.c
index 2fc8258..5e9aec3 100644
--- v3.11-rc3.orig/arch/arm64/mm/hugetlbpage.c
+++ v3.11-rc3/arch/arm64/mm/hugetlbpage.c
@@ -54,6 +54,11 @@ int pud_huge(pud_t pud)
return !(pud_val(pud) & PUD_TABLE_BIT);
}
+int pmd_huge_support(void)
+{
+ return 1;
+}
+
static __init int setup_hugepagesz(char *opt)
{
unsigned long ps = memparse(opt, &opt);
diff --git v3.11-rc3.orig/arch/ia64/mm/hugetlbpage.c v3.11-rc3/arch/ia64/mm/hugetlbpage.c
index 76069c1..68232db 100644
--- v3.11-rc3.orig/arch/ia64/mm/hugetlbpage.c
+++ v3.11-rc3/arch/ia64/mm/hugetlbpage.c
@@ -114,6 +114,11 @@ int pud_huge(pud_t pud)
return 0;
}
+int pmd_huge_support(void)
+{
+ return 0;
+}
+
struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address, pmd_t *pmd, int write)
{
diff --git v3.11-rc3.orig/arch/metag/mm/hugetlbpage.c v3.11-rc3/arch/metag/mm/hugetlbpage.c
index 3c52fa6..0424315 100644
--- v3.11-rc3.orig/arch/metag/mm/hugetlbpage.c
+++ v3.11-rc3/arch/metag/mm/hugetlbpage.c
@@ -110,6 +110,11 @@ int pud_huge(pud_t pud)
return 0;
}
+int pmd_huge_support(void)
+{
+ return 1;
+}
+
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
diff --git v3.11-rc3.orig/arch/mips/mm/hugetlbpage.c v3.11-rc3/arch/mips/mm/hugetlbpage.c
index a7fee0d..01fda44 100644
--- v3.11-rc3.orig/arch/mips/mm/hugetlbpage.c
+++ v3.11-rc3/arch/mips/mm/hugetlbpage.c
@@ -85,6 +85,11 @@ int pud_huge(pud_t pud)
return (pud_val(pud) & _PAGE_HUGE) != 0;
}
+int pmd_huge_support(void)
+{
+ return 1;
+}
+
struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
diff --git v3.11-rc3.orig/arch/powerpc/mm/hugetlbpage.c v3.11-rc3/arch/powerpc/mm/hugetlbpage.c
index 834ca8e..d67db4b 100644
--- v3.11-rc3.orig/arch/powerpc/mm/hugetlbpage.c
+++ v3.11-rc3/arch/powerpc/mm/hugetlbpage.c
@@ -86,6 +86,11 @@ int pgd_huge(pgd_t pgd)
*/
return ((pgd_val(pgd) & 0x3) != 0x0);
}
+
+int pmd_huge_support(void)
+{
+ return 1;
+}
#else
int pmd_huge(pmd_t pmd)
{
@@ -101,6 +106,11 @@ int pgd_huge(pgd_t pgd)
{
return 0;
}
+
+int pmd_huge_support(void)
+{
+ return 0;
+}
#endif
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
diff --git v3.11-rc3.orig/arch/s390/mm/hugetlbpage.c v3.11-rc3/arch/s390/mm/hugetlbpage.c
index 121089d..951ee25 100644
--- v3.11-rc3.orig/arch/s390/mm/hugetlbpage.c
+++ v3.11-rc3/arch/s390/mm/hugetlbpage.c
@@ -117,6 +117,11 @@ int pud_huge(pud_t pud)
return 0;
}
+int pmd_huge_support(void)
+{
+ return 1;
+}
+
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmdp, int write)
{
diff --git v3.11-rc3.orig/arch/sh/mm/hugetlbpage.c v3.11-rc3/arch/sh/mm/hugetlbpage.c
index d776234..0d676a4 100644
--- v3.11-rc3.orig/arch/sh/mm/hugetlbpage.c
+++ v3.11-rc3/arch/sh/mm/hugetlbpage.c
@@ -83,6 +83,11 @@ int pud_huge(pud_t pud)
return 0;
}
+int pmd_huge_support(void)
+{
+ return 0;
+}
+
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
diff --git v3.11-rc3.orig/arch/sparc/mm/hugetlbpage.c v3.11-rc3/arch/sparc/mm/hugetlbpage.c
index d2b5944..9639964 100644
--- v3.11-rc3.orig/arch/sparc/mm/hugetlbpage.c
+++ v3.11-rc3/arch/sparc/mm/hugetlbpage.c
@@ -234,6 +234,11 @@ int pud_huge(pud_t pud)
return 0;
}
+int pmd_huge_support(void)
+{
+ return 0;
+}
+
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
diff --git v3.11-rc3.orig/arch/tile/mm/hugetlbpage.c v3.11-rc3/arch/tile/mm/hugetlbpage.c
index 650ccff..0ac3599 100644
--- v3.11-rc3.orig/arch/tile/mm/hugetlbpage.c
+++ v3.11-rc3/arch/tile/mm/hugetlbpage.c
@@ -198,6 +198,11 @@ int pud_huge(pud_t pud)
return !!(pud_val(pud) & _PAGE_HUGE_PAGE);
}
+int pmd_huge_support(void)
+{
+ return 1;
+}
+
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
diff --git v3.11-rc3.orig/arch/x86/mm/hugetlbpage.c v3.11-rc3/arch/x86/mm/hugetlbpage.c
index 7e73e8c..9d980d8 100644
--- v3.11-rc3.orig/arch/x86/mm/hugetlbpage.c
+++ v3.11-rc3/arch/x86/mm/hugetlbpage.c
@@ -59,6 +59,10 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address,
return NULL;
}
+int pmd_huge_support(void)
+{
+ return 0;
+}
#else
struct page *
@@ -77,6 +81,10 @@ int pud_huge(pud_t pud)
return !!(pud_val(pud) & _PAGE_PSE);
}
+int pmd_huge_support(void)
+{
+ return 1;
+}
#endif
/* x86_64 also uses this file */
diff --git v3.11-rc3.orig/include/linux/hugetlb.h v3.11-rc3/include/linux/hugetlb.h
index 2e02c4e..0393270 100644
--- v3.11-rc3.orig/include/linux/hugetlb.h
+++ v3.11-rc3/include/linux/hugetlb.h
@@ -381,6 +381,16 @@ static inline pgoff_t basepage_index(struct page *page)
extern void dissolve_free_huge_pages(unsigned long start_pfn,
unsigned long end_pfn);
+int pmd_huge_support(void);
+/*
+ * Currently hugepage migration is enabled only for pmd-based hugepage.
+ * This function will be updated when hugepage migration is more widely
+ * supported.
+ */
+static inline int hugepage_migration_support(struct hstate *h)
+{
+ return pmd_huge_support() && (huge_page_shift(h) == PMD_SHIFT);
+}
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};
@@ -409,6 +419,8 @@ static inline pgoff_t basepage_index(struct page *page)
return page->index;
}
#define dissolve_free_huge_pages(s, e) do {} while (0)
+#define pmd_huge_support() 0
+#define hugepage_migration_support(h) 0
#endif /* CONFIG_HUGETLB_PAGE */
#endif /* _LINUX_HUGETLB_H */
diff --git v3.11-rc3.orig/mm/migrate.c v3.11-rc3/mm/migrate.c
index d313737..61f14a1 100644
--- v3.11-rc3.orig/mm/migrate.c
+++ v3.11-rc3/mm/migrate.c
@@ -949,6 +949,16 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
struct page *new_hpage = get_new_page(hpage, private, &result);
struct anon_vma *anon_vma = NULL;
+ /*
+ * Movability of hugepages depends on architectures and hugepage size.
+ * This check is necessary because some callers of hugepage migration
+ * like soft offline and memory hotremove don't walk through page
+ * tables or check whether the hugepage is pmd-based or not before
+ * kicking migration.
+ */
+ if (!hugepage_migration_support(page_hstate(hpage)))
+ return -ENOSYS;
+
if (!new_hpage)
return -ENOMEM;
--
1.8.3.1
--
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