| Subject | Re: [HMM v13 03/18] mm/ZONE_DEVICE/free_hot_cold_page: catch ZONE_DEVICE pages | From | Anshuman Khandual <> | Date | Mon, 21 Nov 2016 13:48:26 +0530 |
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On 11/18/2016 11:48 PM, Jérôme Glisse wrote: > Catch page from ZONE_DEVICE in free_hot_cold_page(). This should never > happen as ZONE_DEVICE page must always have an elevated refcount. > > This is to catch refcounting issues in a sane way for ZONE_DEVICE pages. > > Signed-off-by: Jérôme Glisse <jglisse@redhat.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Ross Zwisler <ross.zwisler@linux.intel.com> > --- > mm/page_alloc.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 0fbfead..09b2630 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2435,6 +2435,16 @@ void free_hot_cold_page(struct page *page, bool cold) > unsigned long pfn = page_to_pfn(page); > int migratetype; > > + /* > + * This should never happen ! Page from ZONE_DEVICE always must have an > + * active refcount. Complain about it and try to restore the refcount. > + */ > + if (is_zone_device_page(page)) { > + VM_BUG_ON_PAGE(is_zone_device_page(page), page); > + page_ref_inc(page); > + return; > + }
This fixes an issue in the existing ZONE_DEVICE code, should not this patch be sent separately not in this series ?
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