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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2013-06-12 14:05:04 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-06-20 11:28:20 -0700
commit79848ba66d91e0c171ff203363e0c96629279c15 (patch)
parent78ef884ebb6c02d45abefc95350f428be7390a26 (diff)
mm: migration: add migrate_entry_wait_huge()
commit 30dad30922ccc733cfdbfe232090cf674dc374dc upstream. When we have a page fault for the address which is backed by a hugepage under migration, the kernel can't wait correctly and do busy looping on hugepage fault until the migration finishes. As a result, users who try to kick hugepage migration (via soft offlining, for example) occasionally experience long delay or soft lockup. This is because pte_offset_map_lock() can't get a correct migration entry or a correct page table lock for hugepage. This patch introduces migration_entry_wait_huge() to solve this. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Andi Kleen <andi@firstfloor.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
3 files changed, 22 insertions, 6 deletions
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index cd42e30b7c6e..96c7110986ca 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -113,6 +113,7 @@ static inline void make_migration_entry_read(swp_entry_t *entry)
extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
unsigned long address);
+extern void migration_entry_wait_huge(struct mm_struct *mm, pte_t *pte);
#define make_migration_entry(page, write) swp_entry(0, 0)
@@ -124,6 +125,8 @@ static inline int is_migration_entry(swp_entry_t swp)
static inline void make_migration_entry_read(swp_entry_t *entryp) { }
static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
unsigned long address) { }
+static inline void migration_entry_wait_huge(struct mm_struct *mm,
+ pte_t *pte) { }
static inline int is_write_migration_entry(swp_entry_t entry)
return 0;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 14420ddbc142..a3498eb134be 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2662,7 +2662,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
if (ptep) {
entry = huge_ptep_get(ptep);
if (unlikely(is_hugetlb_entry_migration(entry))) {
- migration_entry_wait(mm, (pmd_t *)ptep, address);
+ migration_entry_wait_huge(mm, ptep);
return 0;
} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
diff --git a/mm/migrate.c b/mm/migrate.c
index d41b945d53f2..3e315a7e4c8a 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -184,15 +184,14 @@ static void remove_migration_ptes(struct page *old, struct page *new)
* This function is called from do_swap_page().
-void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
- unsigned long address)
+static void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
+ spinlock_t *ptl)
- pte_t *ptep, pte;
- spinlock_t *ptl;
+ pte_t pte;
swp_entry_t entry;
struct page *page;
- ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+ spin_lock(ptl);
pte = *ptep;
if (!is_swap_pte(pte))
goto out;
@@ -220,6 +219,20 @@ out:
pte_unmap_unlock(ptep, ptl);
+void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address)
+ spinlock_t *ptl = pte_lockptr(mm, pmd);
+ pte_t *ptep = pte_offset_map(pmd, address);
+ __migration_entry_wait(mm, ptep, ptl);
+void migration_entry_wait_huge(struct mm_struct *mm, pte_t *pte)
+ spinlock_t *ptl = &(mm)->page_table_lock;
+ __migration_entry_wait(mm, pte, ptl);
/* Returns true if all buffers are successfully locked */
static bool buffer_migrate_lock_buffers(struct buffer_head *head,