On Sun, Jan 17, 2021 at 2:01 PM Andrew Morton akpm@linux-foundation.org wrote:
On Wed, 13 Jan 2021 16:43:32 -0800 Dan Williams dan.j.williams@intel.com wrote:
The conversion to move pfn_to_online_page() internal to soft_offline_page() missed that the get_user_pages() reference taken by the madvise() path needs to be dropped when pfn_to_online_page() fails. Note the direct sysfs-path to soft_offline_page() does not perform a get_user_pages() lookup.
When soft_offline_page() is handed a pfn_valid() && !pfn_to_online_page() pfn the kernel hangs at dax-device shutdown due to a leaked reference.
Fixes: feec24a6139d ("mm, soft-offline: convert parameter to pfn") Cc: Andrew Morton akpm@linux-foundation.org Cc: Naoya Horiguchi nao.horiguchi@gmail.com Cc: Michal Hocko mhocko@kernel.org Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Oscar Salvador osalvador@suse.de Cc: stable@vger.kernel.org Signed-off-by: Dan Williams dan.j.williams@intel.com
A cc:stable patch in the middle is awkward. I'll make this a standalone patch for merging into mainline soon (for 5.11) and shall turn the rest into a 4-patch series, OK?
Sounds good to me.