linux-kernel - [patch -mm] mm, hugetlb: schedule when potentially allocating many hugepages

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Date:   Wed, 7 Jun 2017 21:03:37 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [patch -mm] 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.

Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 Based on -mm only to prevent merge conflicts with
 "mm/hugetlb.c: warn the user when issues arise on boot due to hugepages"

 mm/hugetlb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1754,6 +1754,7 @@ static int gather_surplus_pages(struct hstate *h, int delta)
 			break;
 		}
 		list_add(&page->lru, &surplus_list);
+		cond_resched();
 	}
 	allocated += i;
 
@@ -2222,6 +2223,7 @@ 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];
@@ -2364,6 +2366,7 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
 			ret = alloc_fresh_gigantic_page(h, nodes_allowed);
 		else
 			ret = alloc_fresh_huge_page(h, nodes_allowed);
+		cond_resched();
 		spin_lock(&hugetlb_lock);
 		if (!ret)
 			goto out;