The patch titled
Subject: drivers/base/memory.c: don't access uninitialized memmaps in soft_offline_page_store()
has been added to the -mm tree. Its filename is
drivers-base-memoryc-dont-access-uninitialized-memmaps-in-soft_offline_page_store.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/drivers-base-memoryc-dont-access-uninitialized-memmaps-in-soft_offline_page_store.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/drivers-base-memoryc-dont-access-uninitialized-memmaps-in-soft_offline_page_store.patch
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: drivers/base/memory.c: don't access uninitialized memmaps in soft_offline_page_store()
Uninitialized memmaps contain garbage and in the worst case trigger kernel
BUGs, especially with CONFIG_PAGE_POISONING. They should not get touched.
Right now, when trying to soft-offline a PFN that resides on a memory
block that was never onlined, one gets a misleading error with
CONFIG_PAGE_POISONING:
:/# echo 5637144576 > /sys/devices/system/memory/soft_offline_page
[ 23.097167] soft offline: 0x150000 page already poisoned
But the actual result depends on the garbage in the memmap.
soft_offline_page() can only work with online pages, it returns -EIO in
case of ZONE_DEVICE. Make sure to only forward pages that are online
(iow, managed by the buddy) and, therefore, have an initialized memmap.
Add a check against pfn_to_online_page() and similarly return -EIO.
Link: http://lkml.kernel.org/r/20191010141200.8985-1-david@xxxxxxxxxx
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319]
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/memory.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/base/memory.c~drivers-base-memoryc-dont-access-uninitialized-memmaps-in-soft_offline_page_store
+++ a/drivers/base/memory.c
@@ -540,6 +540,9 @@ static ssize_t soft_offline_page_store(s
pfn >>= PAGE_SHIFT;
if (!pfn_valid(pfn))
return -ENXIO;
+ /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
+ if (!pfn_to_online_page(pfn))
+ return -EIO;
ret = soft_offline_page(pfn_to_page(pfn), 0);
return ret == 0 ? count : ret;
}
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
drivers-base-memoryc-dont-access-uninitialized-memmaps-in-soft_offline_page_store.patch
mm-dont-access-uninitialized-memmaps-in-fs-proc-pagec.patch
mm-memory-failurec-dont-access-uninitialized-memmaps-in-memory_failure.patch
mm-memory_hotplug-export-generic_online_page.patch
hv_balloon-use-generic_online_page.patch
mm-memory_hotplug-remove-__online_page_free-and-__online_page_increment_counters.patch
mm-memory_hotplug-dont-access-uninitialized-memmaps-in-shrink_pgdat_span.patch
mm-memory_hotplug-dont-access-uninitialized-memmaps-in-shrink_zone_span.patch
mm-memory_hotplug-shrink-zones-when-offlining-memory.patch
mm-memory_hotplug-poison-memmap-in-remove_pfn_range_from_zone.patch
mm-memory_hotplug-we-always-have-a-zone-in-find_smallestbiggest_section_pfn.patch
mm-memory_hotplug-dont-check-for-all-holes-in-shrink_zone_span.patch
mm-memory_hotplug-drop-local-variables-in-shrink_zone_span.patch
mm-memory_hotplug-cleanup-__remove_pages.patch
