From: Ralph Campbell <rcampbell@xxxxxxxxxx> Subject: 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/20191113000651.20677-1-rcampbell@xxxxxxxxxx Fixes: 1c6fb1d89e73 ("mm: print more information about mapping in __dump_page") Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Jerome Glisse <jglisse@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/debug.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/mm/debug.c~mm-debug-pageanon-is-true-for-pageksm-pages +++ a/mm/debug.c @@ -77,10 +77,10 @@ void __dump_page(struct page *page, cons 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; _
