From: Xueshi Hu xueshi.hu@smartx.com
mainline inclusion from mainline-v6.7-rc1 commit b72b3c9c34c825c81d205241c5f822fc7835923f category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBE0E0
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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In set_nr_huge_pages(), local variable "count" is used to record persistent_huge_pages(), but when it cames to nodes huge page allocation, the semantics changes to nr_huge_pages. When there exists surplus huge pages and using the interface under /sys/devices/system/node/node*/hugepages to change huge page pool size, this difference can result in the allocation of an unexpected number of huge pages.
Steps to reproduce the bug:
Starting with:
Node 0 Node 1 Total HugePages_Total 0.00 0.00 0.00 HugePages_Free 0.00 0.00 0.00 HugePages_Surp 0.00 0.00 0.00
create 100 huge pages in Node 0 and consume it, then set Node 0 's nr_hugepages to 0.
yields:
Node 0 Node 1 Total HugePages_Total 200.00 0.00 200.00 HugePages_Free 0.00 0.00 0.00 HugePages_Surp 200.00 0.00 200.00
write 100 to Node 1's nr_hugepages
echo 100 > /sys/devices/system/node/node1/\ hugepages/hugepages-2048kB/nr_hugepages
gets:
Node 0 Node 1 Total HugePages_Total 200.00 400.00 600.00 HugePages_Free 0.00 400.00 400.00 HugePages_Surp 200.00 0.00 200.00
Kernel is expected to create only 100 huge pages and it gives 200.
Link: https://lkml.kernel.org/r/20230829033343.467779-1-xueshi.hu@smartx.com Fixes: 9a30523066cd ("hugetlb: add per node hstate attributes") Signed-off-by: Xueshi Hu xueshi.hu@smartx.com Reviewed-by: Mike Kravetz mike.kravetz@oracle.com Cc: Andi Kleen andi@firstfloor.org Cc: Lee Schermerhorn lee.schermerhorn@hp.com Cc: Mel Gorman mel@csn.ul.ie Cc: Muchun Song muchun.song@linux.dev Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/hugetlb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6d53d52652f3..a80b431a8f72 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3696,7 +3696,9 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, if (nid != NUMA_NO_NODE) { unsigned long old_count = count;
- count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; + count += persistent_huge_pages(h) - + (h->nr_huge_pages_node[nid] - + h->surplus_huge_pages_node[nid]); /* * User may have specified a large count value which caused the * above calculation to overflow. In this case, they wanted