[PATCH 5.4 147/152] mm/debug.c: always print flags in dump_page()

Greg Kroah-Hartman
2020-03-03T18:05:36Z

From: Vlastimil Babka <vbabka@suse.cz>

commit 5b57b8f22709f07c0ab5921c94fd66e8c59c3e11 upstream.

Commit 76a1850e4572 ("mm/debug.c: __dump_page() prints an extra line")
inadvertently removed printing of page flags for pages that are neither
anon nor ksm nor have a mapping. Fix that.

Using pr_cont() again would be a solution, but the commit explicitly
removed its use. Avoiding the danger of mixing up split lines from
multiple CPUs might be beneficial for near-panic dumps like this, so fix
this without reintroducing pr_cont().

Link: http://lkml.kernel.org/r/9f884d5c-ca60-dc7b-219c-c081c755fab6@suse.cz
Fixes: 76a1850e4572 ("mm/debug.c: __dump_page() prints an extra line")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reported-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
mm/debug.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

--- a/mm/debug.c
+++ b/mm/debug.c
@@ -47,6 +47,7 @@ void __dump_page(struct page *page, cons
struct address_space *mapping;
bool page_poisoned = PagePoisoned(page);
int mapcount;
+ char *type = "";

/*
* If struct page is poisoned don't access Page*() functions as that
@@ -78,9 +79,9 @@ void __dump_page(struct page *page, cons
page, page_ref_count(page), mapcount,
page->mapping, page_to_pgoff(page));
if (PageKsm(page))
- pr_warn("ksm flags: %#lx(%pGp)\n", page->flags, &page->flags);
+ type = "ksm ";
else if (PageAnon(page))
- pr_warn("anon flags: %#lx(%pGp)\n", page->flags, &page->flags);
+ type = "anon ";
else if (mapping) {
if (mapping->host && mapping->host->i_dentry.first) {
struct dentry *dentry;
@@ -88,10 +89,11 @@ void __dump_page(struct page *page, cons
pr_warn("%ps name:\"%pd\"\n", mapping->a_ops, dentry);
} else
pr_warn("%ps\n", mapping->a_ops);
- pr_warn("flags: %#lx(%pGp)\n", page->flags, &page->flags);
}
BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);

+ pr_warn("%sflags: %#lx(%pGp)\n", type, page->flags, &page->flags);
+
hex_only:
print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
sizeof(unsigned long), page,