Messages in this thread | | | Date | Wed, 30 Apr 2014 12:26:37 +0800 | From | Jiang Liu <> | Subject | Re: [Bugfix v2] sched: fix possible invalid memory access caused by CPU hot-addition |
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Thanks Peter, I will try to find other solutions.
On 2014/4/28 15:09, Peter Zijlstra wrote: > On Mon, Apr 28, 2014 at 10:48:13AM +0800, Jiang Liu wrote: >> Intel platforms with Nehalem/Westmere/IvyBridge CPUs may support socket >> hotplug/online at runtime. The CPU hot-addition flow is: >> 1) handle CPU hot-addition event >> 1.a) gather platform specific information >> 1.b) associate hot-added CPU with NUMA node >> 1.c) create CPU device >> 2) online hot-added CPU through sysfs: >> 2.a) cpu_up() >> 2.b) ->try_online_node() >> 2.c) ->hotadd_new_pgdat() >> 2.d) ->node_set_online() >> >> Between 1.b and 2.c, hot-added CPUs are associated with NUMA nodes >> but those NUMA nodes may still be in offlined state. So we should >> check node_online(nid) before calling kmalloc_node(nid) and friends, >> otherwise it may cause invalid memory access as below. > > So complete and full NAK on this. This is a workaround for a fucked in > the head BIOS. If you're going to do a work around for that they should > live in arch/ space, not in core code. > > The code in question is nearly 7 years old (2.6.24), which leads me to > believe it works just fine for (regular) memory less nodes as I've not > had complaints about it before. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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