+ mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch added to -mm tree

+ mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/hugetlb: avoid unnecessary hugetlb_acct_memory() call
has been added to the -mm tree.  Its filename is
     mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
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@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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
@@ -3588,6 +3588,9 @@ 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
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-hugetlb-fix-potential-double-free-in-hugetlb_register_node-error-path.patch
mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch
mm-compaction-remove-duplicated-vm_bug_on_page-pagelocked.patch