linux-kernel - [PATCH v2] mm: remove redundant check non_swap

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Date:   Mon, 15 Jun 2020 10:54:05 -0700
From:   Ralph Campbell <rcampbell@...dia.com>
To:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
CC:     Jerome Glisse <jglisse@...hat.com>,
        John Hubbard <jhubbard@...dia.com>,
        Christoph Hellwig <hch@....de>,
        Jason Gunthorpe <jgg@...lanox.com>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        Ralph Campbell <rcampbell@...dia.com>
Subject: [PATCH v2] mm: remove redundant check non_swap_entry()

In zap_pte_range(), the check for non_swap_entry() and
is_device_private_entry() is unnecessary since the latter is sufficient
to determine if the page is a device private page. Remove the test for
non_swap_entry() to simplify the code and for clarity.

Signed-off-by: Ralph Campbell <rcampbell@...dia.com>
Reviewed-by: Jason Gunthorpe <jgg@...lanox.com>
---

This is based on the linux 5.8.0-rc1 tree and is intended for Andrew's mm
tree. There is no rush so it could go into 5.9 but I think it is safe
enough to go into an rc after the patch is reviewed.

Changes since v1:
Updated the change log to be more clear.
Added Jason Gunthorpe's reviewed-by.
Rebased to 5.8.0-rc1

 mm/memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index dc7f3543b1fd..bdbb4f97e7d0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1098,7 +1098,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 		}

 		entry = pte_to_swp_entry(ptent);
-		if (non_swap_entry(entry) && is_device_private_entry(entry)) {
+		if (is_device_private_entry(entry)) {
 			struct page *page = device_private_entry_to_page(entry);

 			if (unlikely(details && details->check_mapping)) {
-- 
2.20.1