From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Subject: khugepaged: move up_read(mmap_sem) out of khugepaged_alloc_page() Both variants of khugepaged_alloc_page() do up_read(&mm->mmap_sem) first: no point keep it inside the function. Link: http://lkml.kernel.org/r/1466021202-61880-33-git-send-email-kirill.shutemov@xxxxxxxxxxxxxxx Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/khugepaged.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) diff -puN mm/khugepaged.c~khugepaged-move-up_readmmap_sem-out-of-khugepaged_alloc_page mm/khugepaged.c --- a/mm/khugepaged.c~khugepaged-move-up_readmmap_sem-out-of-khugepaged_alloc_page +++ a/mm/khugepaged.c @@ -739,19 +739,10 @@ static bool khugepaged_prealloc_page(str } static struct page * -khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, - unsigned long address, int node) +khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) { VM_BUG_ON_PAGE(*hpage, *hpage); - /* - * Before allocating the hugepage, release the mmap_sem read lock. - * The allocation can take potentially a long time if it involves - * sync compaction, and we do not need to hold the mmap_sem during - * that. We will recheck the vma after taking it again in write mode. - */ - up_read(&mm->mmap_sem); - *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); if (unlikely(!*hpage)) { count_vm_event(THP_COLLAPSE_ALLOC_FAILED); @@ -812,10 +803,8 @@ static bool khugepaged_prealloc_page(str } static struct page * -khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, - unsigned long address, int node) +khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) { - up_read(&mm->mmap_sem); VM_BUG_ON(!*hpage); return *hpage; @@ -936,8 +925,14 @@ static void collapse_huge_page(struct mm /* Only allocate from the target node */ gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_OTHER_NODE | __GFP_THISNODE; - /* release the mmap_sem read lock. */ - new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node); + /* + * Before allocating the hugepage, release the mmap_sem read lock. + * The allocation can take potentially a long time if it involves + * sync compaction, and we do not need to hold the mmap_sem during + * that. We will recheck the vma after taking it again in write mode. + */ + up_read(&mm->mmap_sem); + new_page = khugepaged_alloc_page(hpage, gfp, node); if (!new_page) { result = SCAN_ALLOC_HUGE_PAGE_FAIL; goto out_nolock; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
