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authorMike Kravetz <mike.kravetz@oracle.com>2021-05-04 18:34:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-05 11:27:22 -0700
commit2938396771c8fd0870b5284319f9e78b4b552a79 (patch)
tree1effd3e89faba079d2fd57dfe6d470c2cea9ad8c /mm
parent262443c0421e832e5312d2b14e0a2640a9f064d7 (diff)
hugetlb: add per-hstate mutex to synchronize user adjustments
The helper routine hstate_next_node_to_alloc accesses and modifies the hstate variable next_nid_to_alloc. The helper is used by the routines alloc_pool_huge_page and adjust_pool_surplus. adjust_pool_surplus is called with hugetlb_lock held. However, alloc_pool_huge_page can not be called with the hugetlb lock held as it will call the page allocator. Two instances of alloc_pool_huge_page could be run in parallel or alloc_pool_huge_page could run in parallel with adjust_pool_surplus which may result in the variable next_nid_to_alloc becoming invalid for the caller and pages being allocated on the wrong node. Both alloc_pool_huge_page and adjust_pool_surplus are only called from the routine set_max_huge_pages after boot. set_max_huge_pages is only called as the reusult of a user writing to the proc/sysfs nr_hugepages, or nr_hugepages_mempolicy file to adjust the number of hugetlb pages. It makes little sense to allow multiple adjustment to the number of hugetlb pages in parallel. Add a mutex to the hstate and use it to only allow one hugetlb page adjustment at a time. This will synchronize modifications to the next_nid_to_alloc variable. Link: https://lkml.kernel.org/r/20210409205254.242291-4-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: David Rientjes <rientjes@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mina Almasry <almasrymina@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/hugetlb.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a5636e1593c5..067fd29a9d51 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2621,6 +2621,11 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
else
return -ENOMEM;
+ /*
+ * resize_lock mutex prevents concurrent adjustments to number of
+ * pages in hstate via the proc/sysfs interfaces.
+ */
+ mutex_lock(&h->resize_lock);
spin_lock(&hugetlb_lock);
/*
@@ -2653,6 +2658,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
if (count > persistent_huge_pages(h)) {
spin_unlock(&hugetlb_lock);
+ mutex_unlock(&h->resize_lock);
NODEMASK_FREE(node_alloc_noretry);
return -EINVAL;
}
@@ -2727,6 +2733,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
out:
h->max_huge_pages = persistent_huge_pages(h);
spin_unlock(&hugetlb_lock);
+ mutex_unlock(&h->resize_lock);
NODEMASK_FREE(node_alloc_noretry);
@@ -3214,6 +3221,7 @@ void __init hugetlb_add_hstate(unsigned int order)
BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
BUG_ON(order == 0);
h = &hstates[hugetlb_max_hstate++];
+ mutex_init(&h->resize_lock);
h->order = order;
h->mask = ~(huge_page_size(h) - 1);
for (i = 0; i < MAX_NUMNODES; ++i)