From: zhong jiang <zhongji...@huawei.com>
commit 29b190fa774dd1b72a1a6f19687d55dc72ea83be upstream.
mpol_rebind_nodemask() is called for MPOL_BIND and MPOL_INTERLEAVE
mempoclicies when the tasks's cpuset's mems_allowed changes. For
policies created without MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES,
it works by remapping the policy's allowed nodes (stored in v.nodes)
using the previous value of mems_allowed (stored in
w.cpuset_mems_allowed) as the domain of map and the new mems_allowed
(passed as nodes) as the range of the map (see the comment of
bitmap_remap() for details).
The result of remapping is stored back as policy's nodemask in v.nodes,
and the new value of mems_allowed should be stored in
w.cpuset_mems_allowed to facilitate the next rebind, if it happens.
However, 213980c0f23b ("mm, mempolicy: simplify rebinding mempolicies
when updating cpusets") introduced a bug where the result of remapping
is stored in w.cpuset_mems_allowed instead. Thus, a mempolicy's
allowed nodes can evolve in an unexpected way after a series of
rebinding due to cpuset mems_allowed changes, possibly binding to a
wrong node or a smaller number of nodes which may e.g. overload them.
This patch fixes the bug so rebinding again works as intended.
[vba...@suse.cz: new changlog]
Link: http://lkml.kernel.org/r/ef6a69c6-c052-b067-8f2c-9d615c619...@suse.cz
Link:
http://lkml.kernel.org/r/1558768043-23184-1-git-send-email-zhongji...@huawei.com
Fixes: 213980c0f23b ("mm, mempolicy: simplify rebinding mempolicies when
updating cpusets")
Signed-off-by: zhong jiang <zhongji...@huawei.com>
Reviewed-by: Vlastimil Babka <vba...@suse.cz>
Cc: Oscar Salvador <osalva...@suse.de>
Cc: Anshuman Khandual <khand...@linux.vnet.ibm.com>
Cc: Michal Hocko <mho...@suse.com>
Cc: Mel Gorman <mgor...@techsingularity.net>
Cc: Andrea Arcangeli <aarca...@redhat.com>
Cc: Ralph Campbell <rcampb...@nvidia.com>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
mm/mempolicy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -305,7 +305,7 @@ static void mpol_rebind_nodemask(struct
else {
nodes_remap(tmp, pol->v.nodes,pol->w.cpuset_mems_allowed,
*nodes);
- pol->w.cpuset_mems_allowed = tmp;
+ pol->w.cpuset_mems_allowed = *nodes;
}
if (nodes_empty(tmp))
