mm/mempolicy.c: fix an incorrect rebind node in mpol_rebind_nodemask
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, 213980c0 ("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. [vbabka@suse.cz: new changlog] Link: http://lkml.kernel.org/r/ef6a69c6-c052-b067-8f2c-9d615c619bb9@suse.cz Link: http://lkml.kernel.org/r/1558768043-23184-1-git-send-email-zhongjiang@huawei.com Fixes: 213980c0 ("mm, mempolicy: simplify rebinding mempolicies when updating cpusets") Signed-off-by: zhong jiang <zhongjiang@huawei.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Oscar Salvador <osalvador@suse.de> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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