| Message ID | 20230829033343.467779-1-xueshi.hu@smartx.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm/hugeltb: fix nodes huge page allocation when there are surplus pages | expand |
On 08/29/23 11:33, Xueshi Hu wrote: > 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. > > Fixes: 9a30523066cd ("hugetlb: add per node hstate attributes") > Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> > Signed-off-by: Xueshi Hu <xueshi.hu@smartx.com> > --- > Change in v2: > - Correct the fix tag Thank you!
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6da626bfb52e..54e2e2e12aa9 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3494,7 +3494,9 @@ 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
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. Fixes: 9a30523066cd ("hugetlb: add per node hstate attributes") Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Xueshi Hu <xueshi.hu@smartx.com> --- Change in v2: - Correct the fix tag - v1: https://lore.kernel.org/linux-mm/20230828233448.GF3290@monkey/T/#t mm/hugetlb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)