Re: [PATCH v3 2/6] mm: Teach pfn_to_online_page() to consider subsection validity
From: Oscar Salvador <osalvador@suse.de>
Date: 2021-01-13 08:31:53
Also in:
lkml, nvdimm
On Tue, Jan 12, 2021 at 11:35:27PM -0800, Dan Williams wrote:
pfn_section_valid() determines pfn validity on subsection granularity
where pfn_valid() may be limited to coarse section granularity.
Explicitly validate subsections after pfn_valid() succeeds.
Fixes: b13bc35193d9 ("mm/hotplug: invalid PFNs from pfn_to_online_page()")
Cc: Qian Cai <redacted>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Reported-by: David Hildenbrand <redacted>
Signed-off-by: Dan Williams <redacted>Reviewed-by: Oscar Salvador <osalvador@suse.de>
quoted hunk ↗ jump to hunk
--- mm/memory_hotplug.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 55a69d4396e7..9f37f8a68da4 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c@@ -308,11 +308,27 @@ static int check_hotplug_memory_addressable(unsigned long pfn, struct page *pfn_to_online_page(unsigned long pfn) { unsigned long nr = pfn_to_section_nr(pfn); + struct mem_section *ms; + + if (nr >= NR_MEM_SECTIONS) + return NULL; + + ms = __nr_to_section(nr); + if (!online_section(ms)) + return NULL; + + /* + * Save some code text when online_section() + + * pfn_section_valid() are sufficient. + */ + if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID)) + if (!pfn_valid(pfn)) + return NULL; + + if (!pfn_section_valid(ms, pfn)) + return NULL; - if (nr < NR_MEM_SECTIONS && online_section_nr(nr) && - pfn_valid_within(pfn)) - return pfn_to_page(pfn); - return NULL; + return pfn_to_page(pfn); } EXPORT_SYMBOL_GPL(pfn_to_online_page);
-- Oscar Salvador SUSE L3