mm/debug.c: PageAnon() is true for PageKsm() pages

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. Link: http://lkml.kernel.org/r/[email protected] Fixes: 1c6fb1d ("mm: print more information about mapping in __dump_page") Signed-off-by: Ralph Campbell <[email protected]> Acked-by: Michal Hocko <[email protected]> Cc: Jerome Glisse <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
chewitt · Nov 16, 2019 · 6855ac4 · 6855ac4
1 parent 76a1850
commit 6855ac4
Showing 1 changed file with 3 additions and 3 deletions.
diff --git 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;