From: David Hildenbrand david@redhat.com Subject: mm/memory-failure.c: don't access uninitialized memmaps in memory_failure()

We should check for pfn_to_online_page() to not access uninitialized memmaps. Reshuffle the code so we don't have to duplicate the error message.

Link: http://lkml.kernel.org/r/20191009142435.3975-3-david@redhat.com Signed-off-by: David Hildenbrand david@redhat.com Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319] Acked-by: Naoya Horiguchi n-horiguchi@ah.jp.nec.com Cc: Michal Hocko mhocko@kernel.org Cc: stable@vger.kernel.org [4.13+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memory-failure.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failurec-dont-access-uninitialized-memmaps-in-memory_failure +++ a/mm/memory-failure.c @@ -1257,17 +1257,19 @@ int memory_failure(unsigned long pfn, in if (!sysctl_memory_failure_recovery) panic("Memory failure on page %lx", pfn);

- if (!pfn_valid(pfn)) { + p = pfn_to_online_page(pfn); + if (!p) { + if (pfn_valid(pfn)) { + pgmap = get_dev_pagemap(pfn, NULL); + if (pgmap) + return memory_failure_dev_pagemap(pfn, flags, + pgmap); + } pr_err("Memory failure: %#lx: memory outside kernel control\n", pfn); return -ENXIO; }

- pgmap = get_dev_pagemap(pfn, NULL); - if (pgmap) - return memory_failure_dev_pagemap(pfn, flags, pgmap); - - p = pfn_to_page(pfn); if (PageHuge(p)) return memory_failure_hugetlb(pfn, flags); if (TestSetPageHWPoison(p)) { _