From 692e0b35427a088bf75d9363788c61c7edbe93a5 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Tue, 24 May 2011 17:12:14 -0700 Subject: [PATCH] mm: thp: optimize memcg charge in khugepaged We don't need to hold the mmmap_sem through mem_cgroup_newpage_charge(), the mmap_sem is only hold for keeping the vma stable and we don't need the vma stable anymore after we return from alloc_hugepage_vma(). Signed-off-by: Andrea Arcangeli Cc: Johannes Weiner Cc: Hugh Dickins Cc: David Rientjes Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 90eef404ec2..615d9743a3c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1771,12 +1771,9 @@ static void collapse_huge_page(struct mm_struct *mm, VM_BUG_ON(address & ~HPAGE_PMD_MASK); #ifndef CONFIG_NUMA + up_read(&mm->mmap_sem); VM_BUG_ON(!*hpage); new_page = *hpage; - if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { - up_read(&mm->mmap_sem); - return; - } #else VM_BUG_ON(*hpage); /* @@ -1791,22 +1788,26 @@ static void collapse_huge_page(struct mm_struct *mm, */ new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address, node, __GFP_OTHER_NODE); + + /* + * After allocating the hugepage, release the mmap_sem read lock in + * preparation for taking it in write mode. + */ + up_read(&mm->mmap_sem); if (unlikely(!new_page)) { - up_read(&mm->mmap_sem); count_vm_event(THP_COLLAPSE_ALLOC_FAILED); *hpage = ERR_PTR(-ENOMEM); return; } +#endif + count_vm_event(THP_COLLAPSE_ALLOC); if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { - up_read(&mm->mmap_sem); +#ifdef CONFIG_NUMA put_page(new_page); +#endif return; } -#endif - - /* after allocating the hugepage upgrade to mmap_sem write mode */ - up_read(&mm->mmap_sem); /* * Prevent all access to pagetables with the exception of -- 2.11.4.GIT