From: Miaohe Lin <linmiaohe@huawei.com>
To: <akpm@linux-foundation.org>
Cc: <ziy@nvidia.com>, <willy@infradead.org>,
<william.kucharski@oracle.com>, <vbabka@suse.cz>,
<peterx@redhat.com>, <yulei.kernel@gmail.com>,
<walken@google.com>, <aneesh.kumar@linux.ibm.com>,
<rcampbell@nvidia.com>, <thomas_os@shipmail.org>,
<yang.shi@linux.alibaba.com>, <richard.weiyang@linux.alibaba.com>,
<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
<linmiaohe@huawei.com>
Subject: [PATCH v3 2/6] mm/huge_memory.c: make get_huge_zero_page() return bool
Date: Thu, 18 Mar 2021 08:27:18 -0400 [thread overview]
Message-ID: <20210318122722.13135-3-linmiaohe@huawei.com> (raw)
In-Reply-To: <20210318122722.13135-1-linmiaohe@huawei.com>
It's guaranteed that huge_zero_page will not be NULL if huge_zero_refcount
is increased successfully. When READ_ONCE(huge_zero_page) is returned,
there must be a huge_zero_page and it can be replaced with returning 'true'
when we do not care about the value of huge_zero_page. We can thus make it
return bool to save READ_ONCE cpu cycles as the return value is just used
to check if huge_zero_page exists.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/huge_memory.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ae16a82da823..01b96c638e73 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -77,18 +77,18 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
return false;
}
-static struct page *get_huge_zero_page(void)
+static bool get_huge_zero_page(void)
{
struct page *zero_page;
retry:
if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
- return READ_ONCE(huge_zero_page);
+ return true;
zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
HPAGE_PMD_ORDER);
if (!zero_page) {
count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
- return NULL;
+ return false;
}
count_vm_event(THP_ZERO_PAGE_ALLOC);
preempt_disable();
@@ -101,7 +101,7 @@ static struct page *get_huge_zero_page(void)
/* We take additional reference here. It will be put back by shrinker */
atomic_set(&huge_zero_refcount, 2);
preempt_enable();
- return READ_ONCE(huge_zero_page);
+ return true;
}
static void put_huge_zero_page(void)
--
2.19.1
next prev parent reply other threads:[~2021-03-18 12:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-18 12:27 [PATCH v3 0/6] Some cleanups for huge_memory Miaohe Lin
2021-03-18 12:27 ` [PATCH v3 1/6] mm/huge_memory.c: rework the function vma_adjust_trans_huge() Miaohe Lin
2021-03-18 12:27 ` Miaohe Lin [this message]
2021-03-18 14:00 ` [PATCH v3 2/6] mm/huge_memory.c: make get_huge_zero_page() return bool Zi Yan
2021-03-18 12:27 ` [PATCH v3 3/6] mm/huge_memory.c: rework the function do_huge_pmd_numa_page() slightly Miaohe Lin
2021-03-18 14:04 ` Zi Yan
2021-03-18 12:27 ` [PATCH v3 4/6] mm/huge_memory.c: remove redundant PageCompound() check Miaohe Lin
2021-03-18 12:27 ` [PATCH v3 5/6] mm/huge_memory.c: remove unused macro TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG Miaohe Lin
2021-03-18 14:12 ` Zi Yan
2021-03-18 12:27 ` [PATCH v3 6/6] mm/huge_memory.c: use helper function migration_entry_to_page() Miaohe Lin
2021-03-18 15:07 ` [PATCH v3 0/6] Some cleanups for huge_memory Peter Xu
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