When we have a page fault for the address which is backed by a hugepage under migration, the kernel can't wait correctly until the migration finishes. This is because pte_offset_map_lock() can't get a correct migration entry for hugepage. This patch adds migration_entry_wait_huge() to separate code path between normal pages and hugepages.
ChangeLog v2: - remove dup in migrate_entry_wait_huge() Signed-off-by: Naoya Horiguchi <[email protected]> --- include/linux/swapops.h | 4 ++++ mm/hugetlb.c | 2 +- mm/migrate.c | 25 ++++++++++++++++++++----- 3 files changed, 25 insertions(+), 6 deletions(-) diff --git v3.9-rc3.orig/include/linux/swapops.h v3.9-rc3/include/linux/swapops.h index 47ead51..f68efdd 100644 --- v3.9-rc3.orig/include/linux/swapops.h +++ v3.9-rc3/include/linux/swapops.h @@ -137,6 +137,8 @@ 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, pmd_t *pmd, + unsigned long address); #else #define make_migration_entry(page, write) swp_entry(0, 0) @@ -148,6 +150,8 @@ 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, pmd_t *pmd, + unsigned long address) { } static inline int is_write_migration_entry(swp_entry_t entry) { return 0; diff --git v3.9-rc3.orig/mm/hugetlb.c v3.9-rc3/mm/hugetlb.c index 0a0be33..98a478e 100644 --- v3.9-rc3.orig/mm/hugetlb.c +++ v3.9-rc3/mm/hugetlb.c @@ -2819,7 +2819,7 @@ 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, (pmd_t *)ptep, address); return 0; } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) return VM_FAULT_HWPOISON_LARGE | diff --git v3.9-rc3.orig/mm/migrate.c v3.9-rc3/mm/migrate.c index 3bbaf5d..ec692a3 100644 --- v3.9-rc3.orig/mm/migrate.c +++ v3.9-rc3/mm/migrate.c @@ -200,15 +200,14 @@ static void remove_migration_ptes(struct page *old, struct page *new) * get to the page and wait until migration is finished. * When we return from this function the fault will be retried. */ -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; @@ -236,6 +235,22 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, pte_unmap_unlock(ptep, ptl); } +void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, + unsigned long address) +{ + pte_t *ptep; + spinlock_t *ptl = pte_lockptr(mm, pmd); + ptep = pte_offset_map(pmd, address); + __migration_entry_wait(mm, ptep, ptl); +} + +void migration_entry_wait_huge(struct mm_struct *mm, pmd_t *pmd, + unsigned long address) +{ + spinlock_t *ptl = pte_lockptr(mm, pmd); + __migration_entry_wait(mm, (pte_t *)pmd, ptl); +} + #ifdef CONFIG_BLOCK /* Returns true if all buffers are successfully locked */ static bool buffer_migrate_lock_buffers(struct buffer_head *head, -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
