Messages in this thread | | | Date | Wed, 23 Apr 2014 07:51:07 +0200 | From | Peter Zijlstra <> | Subject | Re: [Bugfix] sched: fix possible invalid memory access caused by CPU hot-addition |
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On Wed, Apr 23, 2014 at 07:32:13AM +0200, Peter Zijlstra wrote: > On Wed, Apr 23, 2014 at 10:45:13AM +0800, Jiang Liu wrote: > > Hi Peter, > > It's not for memoryless node, but to solve a race window > > in CPU hot-addition. The related CPU hot-addition flow is: > > 1) Handle CPU hot-addition event > > 1.a) gather platform specific information > > 1.b) associate hot-added CPU with a node > > 1.c) create CPU device > > 2) User online hot-added CPUs through sysfs: > > 2.a) cpu_up() > > 2.b) ->try_online_node() > > 2.c) ->hotadd_new_pgdat() > > 2.d) ->node_set_online() > > > > So between 1.b and 2.c, kmalloc_node(nid) may cause invalid > > memory access without the node_online(nid) check. > > Any why was all this not in the Changelog?
Also, do explain what kind of hardware you needed to trigger this. This code has been like this for a good while.
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