Commit edad9d2c authored May 29, 2012 by David Rientjes Committed by Linus Torvalds May 29, 2012

mm, thp: allow fallback when pte_alloc_one() fails for huge pmd



The transparent hugepages feature is careful to not invoke the oom
killer when a hugepage cannot be allocated.

pte_alloc_one() failing in __do_huge_pmd_anonymous_page(), however,
currently results in VM_FAULT_OOM which invokes the pagefault oom killer
to kill a memory-hogging task.

This is unnecessary since it's possible to drop the reference to the
hugepage and fallback to allocating a small page.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent aa2e878e

mm/huge_memory.c

+8 −5

Original line number	Diff line number	Diff line
		@@ -640,11 +640,8 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,

		VM_BUG_ON(!PageCompound(page));
		pgtable = pte_alloc_one(mm, haddr);
		if (unlikely(!pgtable)) {
		mem_cgroup_uncharge_page(page);
		put_page(page);
		if (unlikely(!pgtable))
		return VM_FAULT_OOM;
		}

		clear_huge_page(page, haddr, HPAGE_PMD_NR);
		__SetPageUptodate(page);
		@@ -723,8 +720,14 @@ int do_huge_pmd_anonymous_page(struct mm_struct mm, struct vm_area_struct vma,
		put_page(page);
		goto out;
		}
		if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd,
		page))) {
		mem_cgroup_uncharge_page(page);
		put_page(page);
		goto out;
		}

		return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page);
		return 0;
		}
		out:
		/*