The patch titled
Subject: mm/hugeltb: fix nodes huge page allocation when there are surplus pages
has been added to the -mm mm-unstable branch. Its filename is
mm-hugeltb-fix-nodes-huge-page-allocation-when-there-are-surplus-pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugeltb-fix-nodes-huge-page-allocation-when-there-are-surplus-pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Xueshi Hu <xueshi.hu@xxxxxxxxxx>
Subject: mm/hugeltb: fix nodes huge page allocation when there are surplus pages
Date: Tue, 29 Aug 2023 11:33:43 +0800
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@xxxxxxxxxx
Fixes: 9a30523066cd ("hugetlb: add per node hstate attributes")
Signed-off-by: Xueshi Hu <xueshi.hu@xxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/mm/hugetlb.c~mm-hugeltb-fix-nodes-huge-page-allocation-when-there-are-surplus-pages
+++ a/mm/hugetlb.c
@@ -3457,7 +3457,9 @@ static int set_max_huge_pages(struct hst
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
_
Patches currently in -mm which might be from xueshi.hu@xxxxxxxxxx are
mm-hugeltb-fix-nodes-huge-page-allocation-when-there-are-surplus-pages.patch
