From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx181.postini.com [74.125.245.181]) by kanga.kvack.org (Postfix) with SMTP id D0C956B0031 for ; Tue, 4 Jun 2013 12:45:07 -0400 (EDT) Date: Tue, 04 Jun 2013 12:44:46 -0400 From: Naoya Horiguchi Message-ID: <1370364286-kuz8hc2j-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <20130603132641.GB18588@dhcp22.suse.cz> References: <1369770771-8447-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1369770771-8447-3-git-send-email-n-horiguchi@ah.jp.nec.com> <20130603132641.GB18588@dhcp22.suse.cz> Subject: [PATCH v4] migrate: add migrate_entry_wait_huge() Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Andi Kleen , KOSAKI Motohiro , Rik van Riel , linux-kernel@vger.kernel.org Here is the revised one. Andrew, could you replace the following patches in your tree with this? migrate-add-migrate_entry_wait_huge.patch hugetlbfs-support-split-page-table-lock.patch Thanks, Naoya Horiguchi ---- From: Naoya Horiguchi Date: Tue, 4 Jun 2013 12:26:32 -0400 Subject: [PATCH v4] migrate: add migrate_entry_wait_huge() 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. ChangeLog v4: - replace huge_pte_lockptr with &(mm)->page_table_lock (postponed split page table lock patch) - update description ChangeLog v3: - use huge_pte_lockptr ChangeLog v2: - remove dup in migrate_entry_wait_huge() Signed-off-by: Naoya Horiguchi Reviewed-by: Rik van Riel Cc: stable@vger.kernel.org # 2.6.35 Reviewed-by: Wanpeng Li Reviewed-by: Michal Hocko --- include/linux/swapops.h | 3 +++ mm/hugetlb.c | 2 +- mm/migrate.c | 23 ++++++++++++++++++----- 3 files changed, 22 insertions(+), 6 deletions(-) diff --git a/include/linux/swapops.h b/include/linux/swapops.h index 47ead51..c5fd30d 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -137,6 +137,7 @@ 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) @@ -148,6 +149,8 @@ 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 463fb5e..d793c5e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2865,7 +2865,7 @@ 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 6f2df6e..b8d56a1 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -204,15 +204,14 @@ 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; @@ -240,6 +239,20 @@ 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) +{ + 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, -- 1.7.11.7 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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