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authorDavid Hildenbrand <david@redhat.com>2019-10-18 20:19:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-10-19 06:32:31 -0400
commit641fe2e9387a36f9ee01d7c69382d1fe147a5e98 (patch)
treed68c1be22b8fa86d688c9845af29e7ec674f1f35 /drivers/base/memory.c
parentb9959c7a347d6adbb558fba7e36e9fef3cba3b07 (diff)
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@redhat.com Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319] Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: <stable@vger.kernel.org> [4.13+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/base/memory.c')
-rw-r--r--drivers/base/memory.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 6bea4f3f8040..55907c27075b 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -540,6 +540,9 @@ static ssize_t soft_offline_page_store(struct device *dev,
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;
}