[PATCH] mm/debug: PageAnon() is true for PageKsm() pages

Ralph Campbell
2019-11-13T00:06:58Z

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