From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 75D516B0270 for ; Wed, 23 May 2018 04:27:15 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id l85-v6so12618021pfb.18 for ; Wed, 23 May 2018 01:27:15 -0700 (PDT) Received: from mga17.intel.com (mga17.intel.com. [192.55.52.151]) by mx.google.com with ESMTPS id d2-v6si18038840plh.387.2018.05.23.01.27.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 May 2018 01:27:14 -0700 (PDT) From: "Huang, Ying" Subject: [PATCH -mm -V3 15/21] mm, THP, swap: Support to copy PMD swap mapping when fork() Date: Wed, 23 May 2018 16:26:19 +0800 Message-Id: <20180523082625.6897-16-ying.huang@intel.com> In-Reply-To: <20180523082625.6897-1-ying.huang@intel.com> References: <20180523082625.6897-1-ying.huang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , "Kirill A. Shutemov" , Andrea Arcangeli , Michal Hocko , Johannes Weiner , Shaohua Li , Hugh Dickins , Minchan Kim , Rik van Riel , Dave Hansen , Naoya Horiguchi , Zi Yan From: Huang Ying During fork, the page table need to be copied from parent to child. A PMD swap mapping need to be copied too and the swap reference count need to be increased. When the huge swap cluster has been split already, we need to split the PMD swap mapping and fallback to PTE copying. When swap count continuation failed to allocate a page with GFP_ATOMIC, we need to unlock the spinlock and try again with GFP_KERNEL. Signed-off-by: "Huang, Ying" Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Cc: Michal Hocko Cc: Johannes Weiner Cc: Shaohua Li Cc: Hugh Dickins Cc: Minchan Kim Cc: Rik van Riel Cc: Dave Hansen Cc: Naoya Horiguchi Cc: Zi Yan --- mm/huge_memory.c | 72 ++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 57 insertions(+), 15 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c4eb7737b313..01fdd59fe6d4 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -941,6 +941,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, if (unlikely(!pgtable)) goto out; +retry: dst_ptl = pmd_lock(dst_mm, dst_pmd); src_ptl = pmd_lockptr(src_mm, src_pmd); spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); @@ -948,26 +949,67 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, ret = -EAGAIN; pmd = *src_pmd; -#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION if (unlikely(is_swap_pmd(pmd))) { swp_entry_t entry = pmd_to_swp_entry(pmd); - VM_BUG_ON(!is_pmd_migration_entry(pmd)); - if (is_write_migration_entry(entry)) { - make_migration_entry_read(&entry); - pmd = swp_entry_to_pmd(entry); - if (pmd_swp_soft_dirty(*src_pmd)) - pmd = pmd_swp_mksoft_dirty(pmd); - set_pmd_at(src_mm, addr, src_pmd, pmd); +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION + if (is_migration_entry(entry)) { + if (is_write_migration_entry(entry)) { + make_migration_entry_read(&entry); + pmd = swp_entry_to_pmd(entry); + if (pmd_swp_soft_dirty(*src_pmd)) + pmd = pmd_swp_mksoft_dirty(pmd); + set_pmd_at(src_mm, addr, src_pmd, pmd); + } + add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); + mm_inc_nr_ptes(dst_mm); + pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); + set_pmd_at(dst_mm, addr, dst_pmd, pmd); + ret = 0; + goto out_unlock; } - add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); - mm_inc_nr_ptes(dst_mm); - pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); - set_pmd_at(dst_mm, addr, dst_pmd, pmd); - ret = 0; - goto out_unlock; - } #endif + if (thp_swap_supported() && !non_swap_entry(entry)) { + ret = swap_duplicate(&entry, true); + if (!ret) { + add_mm_counter(dst_mm, MM_SWAPENTS, + HPAGE_PMD_NR); + mm_inc_nr_ptes(dst_mm); + pgtable_trans_huge_deposit(dst_mm, dst_pmd, + pgtable); + set_pmd_at(dst_mm, addr, dst_pmd, pmd); + /* make sure dst_mm is on swapoff's mmlist. */ + if (unlikely(list_empty(&dst_mm->mmlist))) { + spin_lock(&mmlist_lock); + if (list_empty(&dst_mm->mmlist)) + list_add(&dst_mm->mmlist, + &src_mm->mmlist); + spin_unlock(&mmlist_lock); + } + } else if (ret == -ENOTDIR) { + /* + * The swap cluster has been split, split the + * pmd map now + */ + __split_huge_swap_pmd(vma, addr, src_pmd); + pte_free(dst_mm, pgtable); + } else if (ret == -ENOMEM) { + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + ret = add_swap_count_continuation(entry, + GFP_KERNEL); + if (ret < 0) { + ret = -ENOMEM; + pte_free(dst_mm, pgtable); + goto out; + } + goto retry; + } else + VM_BUG_ON(1); + goto out_unlock; + } + VM_BUG_ON(1); + } if (unlikely(!pmd_trans_huge(pmd))) { pte_free(dst_mm, pgtable); -- 2.16.1