From: Mike Kravetz <mike.kravetz@oracle.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Michal Hocko <mhocko@suse.com>,
Shakeel Butt <shakeelb@google.com>,
Oscar Salvador <osalvador@suse.de>,
David Hildenbrand <david@redhat.com>,
Muchun Song <songmuchun@bytedance.com>,
David Rientjes <rientjes@google.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Peter Zijlstra <peterz@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
HORIGUCHI NAOYA <naoya.horiguchi@nec.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Waiman Long <longman@redhat.com>, Peter Xu <peterx@redhat.com>,
Mina Almasry <almasrymina@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: [RFC PATCH 2/8] hugetlb: recompute min_count when dropping hugetlb_lock
Date: Fri, 19 Mar 2021 15:42:03 -0700 [thread overview]
Message-ID: <20210319224209.150047-3-mike.kravetz@oracle.com> (raw)
In-Reply-To: <20210319224209.150047-1-mike.kravetz@oracle.com>
The routine set_max_huge_pages reduces the number of hugetlb_pages,
by calling free_pool_huge_page in a loop. It does this as long as
persistent_huge_pages() is above a calculated min_count value.
However, this loop can conditionally drop hugetlb_lock and in some
circumstances free_pool_huge_page can drop hugetlb_lock. If the
lock is dropped, counters could change the calculated min_count
value may no longer be valid.
The routine try_to_free_low has the same issue.
Recalculate min_count in each loop iteration as hugetlb_lock may have
been dropped.
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
mm/hugetlb.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d5be25f910e8..c537274c2a38 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2521,11 +2521,20 @@ static void __init report_hugepages(void)
}
}
+static inline unsigned long min_hp_count(struct hstate *h, unsigned long count)
+{
+ unsigned long min_count;
+
+ min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
+ return max(count, min_count);
+}
+
#ifdef CONFIG_HIGHMEM
static void try_to_free_low(struct hstate *h, unsigned long count,
nodemask_t *nodes_allowed)
{
int i;
+ unsigned long min_count = min_hp_count(h, count);
if (hstate_is_gigantic(h))
return;
@@ -2534,7 +2543,7 @@ static void try_to_free_low(struct hstate *h, unsigned long count,
struct page *page, *next;
struct list_head *freel = &h->hugepage_freelists[i];
list_for_each_entry_safe(page, next, freel, lru) {
- if (count >= h->nr_huge_pages)
+ if (min_count >= h->nr_huge_pages)
return;
if (PageHighMem(page))
continue;
@@ -2542,6 +2551,12 @@ static void try_to_free_low(struct hstate *h, unsigned long count,
update_and_free_page(h, page);
h->free_huge_pages--;
h->free_huge_pages_node[page_to_nid(page)]--;
+
+ /*
+ * update_and_free_page could have dropped lock so
+ * recompute min_count.
+ */
+ min_count = min_hp_count(h, count);
}
}
}
@@ -2695,13 +2710,15 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
* and won't grow the pool anywhere else. Not until one of the
* sysctls are changed, or the surplus pages go out of use.
*/
- min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
- min_count = max(count, min_count);
- try_to_free_low(h, min_count, nodes_allowed);
+ min_count = min_hp_count(h, count);
+ try_to_free_low(h, count, nodes_allowed);
while (min_count < persistent_huge_pages(h)) {
if (!free_pool_huge_page(h, nodes_allowed, 0))
break;
cond_resched_lock(&hugetlb_lock);
+
+ /* Recompute min_count in case hugetlb_lock was dropped */
+ min_count = min_hp_count(h, count);
}
while (count < persistent_huge_pages(h)) {
if (!adjust_pool_surplus(h, nodes_allowed, 1))
--
2.30.2
next prev parent reply other threads:[~2021-03-19 22:43 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 22:42 [RFC PATCH 0/8] make hugetlb put_page safe for all calling contexts Mike Kravetz
2021-03-19 22:42 ` [RFC PATCH 1/8] hugetlb: add per-hstate mutex to synchronize user adjustments Mike Kravetz
2021-03-22 13:59 ` Michal Hocko
2021-03-22 16:57 ` Mike Kravetz
2021-03-23 7:48 ` Michal Hocko
2021-03-19 22:42 ` Mike Kravetz [this message]
2021-03-22 14:07 ` [RFC PATCH 2/8] hugetlb: recompute min_count when dropping hugetlb_lock Michal Hocko
2021-03-22 23:07 ` Mike Kravetz
2021-03-23 7:50 ` Michal Hocko
2021-03-23 8:01 ` Peter Zijlstra
2021-03-23 8:14 ` Michal Hocko
2021-03-23 23:18 ` Mike Kravetz
2021-03-24 8:36 ` Michal Hocko
2021-03-24 16:43 ` Mike Kravetz
2021-03-19 22:42 ` [RFC PATCH 3/8] hugetlb: create remove_hugetlb_page() to separate functionality Mike Kravetz
2021-03-22 14:15 ` Michal Hocko
2021-03-22 17:01 ` Mike Kravetz
2021-03-19 22:42 ` [RFC PATCH 4/8] hugetlb: call update_and_free_page without hugetlb_lock Mike Kravetz
2021-03-22 14:19 ` Michal Hocko
2021-03-19 22:42 ` [RFC PATCH 5/8] hugetlb: change free_pool_huge_page to remove_pool_huge_page Mike Kravetz
2021-03-22 14:31 ` Michal Hocko
2021-03-22 23:28 ` Mike Kravetz
2021-03-23 7:57 ` Michal Hocko
2021-03-24 1:03 ` Mike Kravetz
2021-03-24 8:40 ` Michal Hocko
2021-03-24 16:38 ` Mike Kravetz
2021-03-24 16:50 ` Michal Hocko
2021-03-19 22:42 ` [RFC PATCH 6/8] hugetlb: make free_huge_page irq safe Mike Kravetz
2021-03-21 19:55 ` Mike Kravetz
2021-03-22 13:36 ` [hugetlb] cd190f60f9: BUG:sleeping_function_called_from_invalid_context_at_mm/hugetlb.c kernel test robot
2021-03-22 14:35 ` [RFC PATCH 6/8] hugetlb: make free_huge_page irq safe Michal Hocko
2021-03-19 22:42 ` [RFC PATCH 7/8] hugetlb: add update_and_free_page_no_sleep for irq context Mike Kravetz
2021-03-20 1:18 ` Hillf Danton
2021-03-25 0:26 ` Mike Kravetz
2021-03-22 8:41 ` Peter Zijlstra
2021-03-22 17:42 ` Mike Kravetz
2021-03-22 18:10 ` Roman Gushchin
2021-03-23 18:51 ` Mike Kravetz
2021-03-23 19:07 ` Roman Gushchin
2021-03-24 8:43 ` Michal Hocko
2021-03-24 16:53 ` Mike Kravetz
2021-03-22 20:43 ` Peter Zijlstra
2021-03-22 14:42 ` Michal Hocko
2021-03-22 14:46 ` Michal Hocko
2021-03-19 22:42 ` [RFC PATCH 8/8] hugetlb: track hugetlb pages allocated via cma_alloc Mike Kravetz
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