mm, hugetlb: schedule when potentially allocating many hugepages

A few hugetlb allocators loop while calling the page allocator and can
potentially prevent rescheduling if the page allocator slowpath is not
utilized.

Conditionally schedule when large numbers of hugepages can be allocated.

Anshuman:
 "Fixes a task which was getting hung while writing like 10000 hugepages
  (16MB on POWER8) into /proc/sys/vm/nr_hugepages."

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1706091535300.66176@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Tested-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 01c11ceb47d6c0c713d9a49bbbb9706e5430e383..176e0318960f93e724280ee37ea1e1b3a66b3e9d 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1781,6 +1781,7 @@ retry:
                        break;
                }
                list_add(&page->lru, &surplus_list);
+               cond_resched();
        }
        allocated += i;
 
@@ -2249,6 +2250,7 @@ static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
                } else if (!alloc_fresh_huge_page(h,
                                         &node_states[N_MEMORY]))
                        break;
+               cond_resched();
        }
        if (i < h->max_huge_pages) {
                char buf[32];