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| author | Dan Williams <dan.j.williams@intel.com> | 2021-02-25 17:17:01 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-26 09:41:00 -0800 |
| commit | 9f9b02e5b3468e665a576a86ceb72f753001710b (patch) | |
| tree | 5e5ea6a3732a2680f8afecae4208d55ff4e1df4e /mm | |
| parent | 9f605f260594f99b950062fd62244251e85dbd2b (diff) | |
| download | linux-9f9b02e5b3468e665a576a86ceb72f753001710b.tar.gz linux-9f9b02e5b3468e665a576a86ceb72f753001710b.tar.bz2 linux-9f9b02e5b3468e665a576a86ceb72f753001710b.zip | |
mm: teach pfn_to_online_page() to consider subsection validity
pfn_to_online_page is primarily used to filter out offline or fully
uninitialized pages. pfn_valid resp. online_section_nr have a coarse
per memory section granularity. If a section shared with a partially
offline memory (e.g. part of ZONE_DEVICE) then pfn_to_online_page
would lead to a false positive on some pfns. Fix this by adding
pfn_section_valid check which is subsection aware.
[mhocko@kernel.org: changelog rewrite]
Link: https://lkml.kernel.org/r/161058500148.1840162.4365921007820501696.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: b13bc35193d9 ("mm/hotplug: invalid PFNs from pfn_to_online_page()")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory_hotplug.c | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index fc6cdd99941b..02378f11e2d6 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -308,11 +308,26 @@ 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) && !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); |