Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   "Matthew Wilcox (Oracle)" <willy@infradead.org>
To:     linux-mm@kvack.org
Cc:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        William Kucharski <william.kucharski@oracle.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Chris Wilson <chris@chris-wilson.co.uk>,
        Matthew Auld <matthew.auld@intel.com>,
        Huang Ying <ying.huang@intel.com>,
        intel-gfx@lists.freedesktop.org, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 2/8] mm: Use find_get_swap_page in memcontrol
Date:   Wed, 19 Aug 2020 19:48:44 +0100
Message-Id: <20200819184850.24779-3-willy@infradead.org>
In-Reply-To: <20200819184850.24779-1-willy@infradead.org>
References: <20200819184850.24779-1-willy@infradead.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The current code does not protect against swapoff of the underlying
swap device, so this is a bug fix as well as a worthwhile reduction in
code complexity.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/memcontrol.c | 25 ++-----------------------
 1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b807952b4d43..4075f214a841 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5539,35 +5539,14 @@ static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
 static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
 			unsigned long addr, pte_t ptent, swp_entry_t *entry)
 {
-	struct page *page = NULL;
-	struct address_space *mapping;
-	pgoff_t pgoff;
-
 	if (!vma->vm_file) /* anonymous vma */
 		return NULL;
 	if (!(mc.flags & MOVE_FILE))
 		return NULL;
 
-	mapping = vma->vm_file->f_mapping;
-	pgoff = linear_page_index(vma, addr);
-
 	/* page is moved even if it's not RSS of this task(page-faulted). */
-#ifdef CONFIG_SWAP
-	/* shmem/tmpfs may report page out on swap: account for that too. */
-	if (shmem_mapping(mapping)) {
-		page = find_get_entry(mapping, pgoff);
-		if (xa_is_value(page)) {
-			swp_entry_t swp = radix_to_swp_entry(page);
-			*entry = swp;
-			page = find_get_page(swap_address_space(swp),
-					     swp_offset(swp));
-		}
-	} else
-		page = find_get_page(mapping, pgoff);
-#else
-	page = find_get_page(mapping, pgoff);
-#endif
-	return page;
+	return find_get_swap_page(vma->vm_file->f_mapping,
+			linear_page_index(vma, addr));
 }
 
 /**
-- 
2.28.0