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From:   Mike Kravetz <mike.kravetz@oracle.com>
To:     linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc:     Michal Hocko <mhocko@suse.com>, Oscar Salvador <osalvador@suse.de>,
        Muchun Song <songmuchun@bytedance.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mike Kravetz <mike.kravetz@oracle.com>
Subject: [PATCH] hugetlb: document the new location of page subpool pointer
Date:   Tue, 23 Feb 2021 20:04:39 -0800
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Expand comments, no functional change.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 include/linux/hugetlb.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index cccd1aab69dd..c0467a7a1fe0 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -476,6 +476,9 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
  * huegtlb page specific state flags.  These flags are located in page.private
  * of the hugetlb head page.  Functions created via the below macros should be
  * used to manipulate these flags.
+ * Note: The hugetlb page subpool pointer previously located at page.private
+ * was moved to page[1].private to make room for flags in the head page.  See
+ * hugetlb_page_subpool().
  *
  * HPG_restore_reserve - Set when a hugetlb page consumes a reservation at
  *	allocation time.  Cleared when page is fully instantiated.  Free
-- 
2.29.2