| Message ID | 20181119101616.8901-8-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1,1/8] mm: balloon: update comment about isolation/migration/compaction | expand |
On Mon 19-11-18 11:16:15, David Hildenbrand wrote: > Let's use pfn_to_online_page() instead of pfn_to_page() when checking > for saveable pages to not save/restore offline memory sections. > > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> > Cc: Pavel Machek <pavel@ucw.cz> > Cc: Len Brown <len.brown@intel.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: "Michael S. Tsirkin" <mst@redhat.com> > Suggested-by: Michal Hocko <mhocko@kernel.org> > Signed-off-by: David Hildenbrand <david@redhat.com> I have only a very vague understanding of this specific code but I do not really see any real reason for checking offlined ranges. Also offline pfn ranges might have uninitialized struct pages so making any decisions of the struct page is basically undefined behavior. Acked-by: Michal Hocko <mhocko@suse.com> > --- > kernel/power/snapshot.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c > index 640b2034edd6..87e6dd57819f 100644 > --- a/kernel/power/snapshot.c > +++ b/kernel/power/snapshot.c > @@ -1215,8 +1215,8 @@ static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn) > if (!pfn_valid(pfn)) > return NULL; > > - page = pfn_to_page(pfn); > - if (page_zone(page) != zone) > + page = pfn_to_online_page(pfn); > + if (!page || page_zone(page) != zone) > return NULL; > > BUG_ON(!PageHighMem(page)); > @@ -1277,8 +1277,8 @@ static struct page *saveable_page(struct zone *zone, unsigned long pfn) > if (!pfn_valid(pfn)) > return NULL; > > - page = pfn_to_page(pfn); > - if (page_zone(page) != zone) > + page = pfn_to_online_page(pfn); > + if (!page || page_zone(page) != zone) > return NULL; > > BUG_ON(PageHighMem(page)); > -- > 2.17.2
On Mon 2018-11-19 11:16:15, David Hildenbrand wrote: > Let's use pfn_to_online_page() instead of pfn_to_page() when checking > for saveable pages to not save/restore offline memory sections. > > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Pavel Machek <pavel@ucw.cz>
On Monday, November 19, 2018 11:16:15 AM CET David Hildenbrand wrote: > Let's use pfn_to_online_page() instead of pfn_to_page() when checking > for saveable pages to not save/restore offline memory sections. > > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> > Cc: Pavel Machek <pavel@ucw.cz> > Cc: Len Brown <len.brown@intel.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: "Michael S. Tsirkin" <mst@redhat.com> > Suggested-by: Michal Hocko <mhocko@kernel.org> > Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > kernel/power/snapshot.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c > index 640b2034edd6..87e6dd57819f 100644 > --- a/kernel/power/snapshot.c > +++ b/kernel/power/snapshot.c > @@ -1215,8 +1215,8 @@ static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn) > if (!pfn_valid(pfn)) > return NULL; > > - page = pfn_to_page(pfn); > - if (page_zone(page) != zone) > + page = pfn_to_online_page(pfn); > + if (!page || page_zone(page) != zone) > return NULL; > > BUG_ON(!PageHighMem(page)); > @@ -1277,8 +1277,8 @@ static struct page *saveable_page(struct zone *zone, unsigned long pfn) > if (!pfn_valid(pfn)) > return NULL; > > - page = pfn_to_page(pfn); > - if (page_zone(page) != zone) > + page = pfn_to_online_page(pfn); > + if (!page || page_zone(page) != zone) > return NULL; > > BUG_ON(PageHighMem(page)); >
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 640b2034edd6..87e6dd57819f 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -1215,8 +1215,8 @@ static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn) if (!pfn_valid(pfn)) return NULL; - page = pfn_to_page(pfn); - if (page_zone(page) != zone) + page = pfn_to_online_page(pfn); + if (!page || page_zone(page) != zone) return NULL; BUG_ON(!PageHighMem(page)); @@ -1277,8 +1277,8 @@ static struct page *saveable_page(struct zone *zone, unsigned long pfn) if (!pfn_valid(pfn)) return NULL; - page = pfn_to_page(pfn); - if (page_zone(page) != zone) + page = pfn_to_online_page(pfn); + if (!page || page_zone(page) != zone) return NULL; BUG_ON(PageHighMem(page));
Let's use pfn_to_online_page() instead of pfn_to_page() when checking for saveable pages to not save/restore offline memory sections. Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Pavel Machek <pavel@ucw.cz> Cc: Len Brown <len.brown@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Suggested-by: Michal Hocko <mhocko@kernel.org> Signed-off-by: David Hildenbrand <david@redhat.com> --- kernel/power/snapshot.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)