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From: Ralph Campbell <rcampbell@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
	Ralph Campbell <rcampbell@nvidia.com>
Subject: [PATCH] mm/debug: PageAnon() is true for PageKsm() pages
Date: Tue, 12 Nov 2019 16:06:51 -0800
Message-ID: <20191113000651.20677-1-rcampbell@nvidia.com> (raw)

PageAnon() and PageKsm() use the low two bits of the page->mapping pointer
to indicate the page type. PageAnon() only checks the LSB while PageKsm()
checks the least significant 2 bits are equal to 3. Therefore, PageAnon()
is true for KSM pages.
__dump_page() incorrectly will never print "ksm" because it checks
PageAnon() first. Fix this by checking PageKsm() first.

Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
---
 mm/debug.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/debug.c b/mm/debug.c
index 772d4cf0691f..0461df1207cb 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -77,10 +77,10 @@ void __dump_page(struct page *page, const char *reason)
 		pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx\n",
 			page, page_ref_count(page), mapcount,
 			page->mapping, page_to_pgoff(page));
-	if (PageAnon(page))
-		pr_warn("anon flags: %#lx(%pGp)\n", page->flags, &page->flags);
-	else if (PageKsm(page))
+	if (PageKsm(page))
 		pr_warn("ksm flags: %#lx(%pGp)\n", page->flags, &page->flags);
+	else if (PageAnon(page))
+		pr_warn("anon flags: %#lx(%pGp)\n", page->flags, &page->flags);
 	else if (mapping) {
 		if (mapping->host && mapping->host->i_dentry.first) {
 			struct dentry *dentry;
-- 
2.20.1



             reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-13  0:06 Ralph Campbell [this message]
2019-11-14 13:59 ` Michal Hocko
2019-11-15  2:32   ` lixinhai.lxh
2019-11-15  5:47     ` lixinhai.lxh

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