From: Miaohe Lin <linmiaohe@xxxxxxxxxx> Subject: mm/hugetlb: avoid unnecessary hugetlb_acct_memory() call When reservation accounting remains unchanged, hugetlb_acct_memory() will do nothing except holding and releasing hugetlb_lock. We should avoid this unnecessary hugetlb_lock lock/unlock cycle which is happening on 'most' hugetlb munmap operations by check delta against 0 at the beginning of hugetlb_acct_memory. Link: https://lkml.kernel.org/r/20210115092013.61012-1-linmiaohe@xxxxxxxxxx Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/hugetlb.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/hugetlb.c~mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call +++ a/mm/hugetlb.c @@ -3591,6 +3591,9 @@ static int hugetlb_acct_memory(struct hs { int ret = -ENOMEM; + if (!delta) + return 0; + spin_lock(&hugetlb_lock); /* * When cpuset is configured, it breaks the strict hugetlb page _
