From: Naoya Horiguchi Date: Wed, 12 Jun 2013 21:05:04 +0000 (-0700) Subject: mm: migration: add migrate_entry_wait_huge() X-Git-Tag: v3.2.47~7 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4207b3f2766e3862d8a0406898236a1eaf226678;p=thirdparty%2Fkernel%2Fstable.git 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 Reviewed-by: Rik van Riel Reviewed-by: Wanpeng Li Reviewed-by: Michal Hocko Cc: Mel Gorman Cc: Andi Kleen Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- diff --git a/include/linux/swapops.h b/include/linux/swapops.h index d69556075b09b..7f62faf486966 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -136,6 +136,7 @@ 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); #else #define make_migration_entry(page, write) swp_entry(0, 0) @@ -147,6 +148,8 @@ 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 70b473338da0f..2dcd7169cd78b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2751,7 +2751,7 @@ 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))) return VM_FAULT_HWPOISON_LARGE | diff --git a/mm/migrate.c b/mm/migrate.c index e1052d15a14ec..09d6a9d6806bb 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); +} + #ifdef CONFIG_BLOCK /* Returns true if all buffers are successfully locked */ static bool buffer_migrate_lock_buffers(struct buffer_head *head,