| Message ID | 20191006085646.5768-7-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v6,01/10] mm/memunmap: Don't access uninitialized memmap in memunmap_pages() | expand |
On 06.10.19 10:56, David Hildenbrand wrote: > Let's poison the pages similar to when adding new memory in > sparse_add_section(). Also call remove_pfn_range_from_zone() from > memunmap_pages(), so we can poison the memmap from there as well. > > While at it, calculate the pfn in memunmap_pages() only once. FWIW, this comment is stale and could be dropped :)
On Sun, Oct 06, 2019 at 10:56:42AM +0200, David Hildenbrand wrote: > Let's poison the pages similar to when adding new memory in > sparse_add_section(). Also call remove_pfn_range_from_zone() from > memunmap_pages(), so we can poison the memmap from there as well. > > While at it, calculate the pfn in memunmap_pages() only once. > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: David Hildenbrand <david@redhat.com> > Cc: Oscar Salvador <osalvador@suse.de> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Pavel Tatashin <pasha.tatashin@soleen.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Signed-off-by: David Hildenbrand <david@redhat.com> Looks good to me, it is fine as long as we do not access those pages later on, and if my eyes did not lie to me, we have to proper checks (pfn_to_online_page) in place to avoid that, so: Reviewed-by: Oscar Salvador <osalvador@suse.de>
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 5b003ffa5dc9..bf5173e7913d 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -464,6 +464,9 @@ void __ref remove_pfn_range_from_zone(struct zone *zone, struct pglist_data *pgdat = zone->zone_pgdat; unsigned long flags; + /* Poison struct pages because they are now uninitialized again. */ + page_init_poison(pfn_to_page(start_pfn), sizeof(struct page) * nr_pages); + #ifdef CONFIG_ZONE_DEVICE /* * Zone shrinking code cannot properly deal with ZONE_DEVICE. So diff --git a/mm/memremap.c b/mm/memremap.c index 70263e6f093e..7fed8bd32a18 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -139,6 +139,8 @@ void memunmap_pages(struct dev_pagemap *pgmap) nid = page_to_nid(first_page); mem_hotplug_begin(); + remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(res->start), + PHYS_PFN(resource_size(res))); if (pgmap->type == MEMORY_DEVICE_PRIVATE) { __remove_pages(PHYS_PFN(res->start), PHYS_PFN(resource_size(res)), NULL);
Let's poison the pages similar to when adding new memory in sparse_add_section(). Also call remove_pfn_range_from_zone() from memunmap_pages(), so we can poison the memmap from there as well. While at it, calculate the pfn in memunmap_pages() only once. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: David Hildenbrand <david@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- mm/memory_hotplug.c | 3 +++ mm/memremap.c | 2 ++ 2 files changed, 5 insertions(+)