[PATCHv8 28/32] khugepaged: move up_read(mmap_sem) out of khugepaged_alloc_page()

Kirill A. Shutemov
2016-05-12T15:43:55Z

Both variants of khugepaged_alloc_page() do up_read(&mm->mmap_sem)
first: no point keep it inside the function.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/khugepaged.c | 25 ++++++++++---------------
1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index ef229cdfe5b7..c4693fd12f76 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -736,19 +736,10 @@ static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
}

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);
@@ -809,10 +800,8 @@ static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
}

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;
@@ -896,8 +885,14 @@ static void collapse_huge_page(struct mm_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;
--
2.8.1