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From:   luofei <luofei@unicloud.com>
To:     <mike.kravetz@oracle.com>, <akpm@linux-foundation.org>
CC:     <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        luofei <luofei@unicloud.com>
Subject: [PATCH] hugetlbfs: fix description about atomic allocation of vmemmap pages when free huge page
Date:   Tue, 15 Mar 2022 00:23:55 -0400
Message-ID: <20220315042355.362810-1-luofei@unicloud.com>
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No matter what context update_and_free_page() is called in,
the flag for allocating the vmemmap page is fixed
(GFP_KERNEL | __GFP_NORETRY | __GFP_THISNODE), and no atomic
allocation is involved, so the description of atomicity here
is somewhat inappropriate.

and the atomic parameter naming of update_and_free_page() is
somewhat misleading.

Signed-off-by: luofei <luofei@unicloud.com>
---
 mm/hugetlb.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index f8ca7cca3c1a..239ef82b7897 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1570,8 +1570,8 @@ static void __update_and_free_page(struct hstate *h, struct page *page)
 
 /*
  * As update_and_free_page() can be called under any context, so we cannot
- * use GFP_KERNEL to allocate vmemmap pages. However, we can defer the
- * actual freeing in a workqueue to prevent from using GFP_ATOMIC to allocate
+ * use GFP_ATOMIC to allocate vmemmap pages. However, we can defer the
+ * actual freeing in a workqueue to prevent waits caused by allocating
  * the vmemmap pages.
  *
  * free_hpage_workfn() locklessly retrieves the linked list of pages to be
@@ -1617,16 +1617,14 @@ static inline void flush_free_hpage_work(struct hstate *h)
 }
 
 static void update_and_free_page(struct hstate *h, struct page *page,
-				 bool atomic)
+				 bool delay)
 {
-	if (!HPageVmemmapOptimized(page) || !atomic) {
+	if (!HPageVmemmapOptimized(page) || !delay) {
 		__update_and_free_page(h, page);
 		return;
 	}
 
 	/*
-	 * Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap pages.
-	 *
 	 * Only call schedule_work() if hpage_freelist is previously
 	 * empty. Otherwise, schedule_work() had been called but the workfn
 	 * hasn't retrieved the list yet.
-- 
2.27.0