From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Naoya Horiguchi , Rik van Riel , Wanpeng Li , Michal Hocko , Mel Gorman , Andi Kleen , KOSAKI Motohiro , Andrew Morton , Linus Torvalds Subject: [ 5/7] mm: migration: add migrate_entry_wait_huge() Date: Tue, 18 Jun 2013 09:10:42 -0700 Message-Id: <20130618160912.399693196@linuxfoundation.org> In-Reply-To: <20130618160911.721012782@linuxfoundation.org> References: <20130618160911.721012782@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: From: Greg Kroah-Hartman 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Naoya Horiguchi 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: Greg Kroah-Hartman --- include/linux/swapops.h | 3 +++ mm/hugetlb.c | 2 +- mm/migrate.c | 23 ++++++++++++++++++----- 3 files changed, 22 insertions(+), 6 deletions(-) --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -113,6 +113,7 @@ static inline void make_migration_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) @@ -124,6 +125,8 @@ static inline int is_migration_entry(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; --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2662,7 +2662,7 @@ int hugetlb_fault(struct mm_struct *mm, 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 | --- a/mm/migrate.c +++ b/mm/migrate.c @@ -184,15 +184,14 @@ static void remove_migration_ptes(struct * * 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,