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authorRobert Jennings <rcj@linux.vnet.ibm.com>2013-07-24 20:13:21 -0500
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-08-01 13:11:47 +1000
commit3be7db6ab45b21345386d1a466da133b19cde5e4 (patch)
tree55f7be0aa23b1d0647aea236abde4a854009d392 /drivers/macintosh
parent8d7c55d01e4648605fd0dacc82d8d3989ead4db7 (diff)
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powerpc: VPHN topology change updates all siblings
When an associativity level change is found for one thread, the siblings threads need to be updated as well. This is done today for PRRN in stage_topology_update() but is missing for VPHN in update_cpu_associativity_changes_mask(). This patch will correctly update all thread siblings during a topology change. Without this patch a topology update can result in a CPU in init_sched_groups_power() getting stuck indefinitely in a loop. This loop is built in build_sched_groups(). As a result of the thread moving to a node separate from its siblings the struct sched_group will have its next pointer set to point to itself rather than the sched_group struct of the next thread. This happens because we have a domain without the SD_OVERLAP flag, which is correct, and a topology that doesn't conform with reality (threads on the same core assigned to different numa nodes). When this list is traversed by init_sched_groups_power() it will reach the thread's sched_group structure and loop indefinitely; the cpu will be stuck at this point. The bug was exposed when VPHN was enabled in commit b7abef0 (v3.9). Cc: <stable@vger.kernel.org> [v3.9+] Reported-by: Jan Stancek <jstancek@redhat.com> Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'drivers/macintosh')
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