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Commit 988ddb71 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

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@linux.intel.com


Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b46e756f

mm/khugepaged.c

+10 −15
Original line number Diff line number Diff line
@@ -739,19 +739,10 @@ 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);
@@ -812,10 +803,8 @@ 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;
@@ -936,8 +925,14 @@ 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;