Messages in this thread | | | Subject | Re: [PATCH] x86,mm: print likely CPU at segfault time | From | Dave Hansen <> | Date | Mon, 19 Jul 2021 12:20:24 -0700 |
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On 7/19/21 12:00 PM, Rik van Riel wrote: > In a large enough fleet of computers, it is common to have a few bad > CPUs. Those can often be identified by seeing that some commonly run > kernel code (that runs fine everywhere else) keeps crashing on the > same CPU core on a particular bad system.
I've encountered a few of these kinds of things over the years. This is *definitely* useful. What you've proposed here is surely the simplest thing we could print and probably also offers the best bang for our buck.
The only other thing I thought of is that it might be nice to print out the core id instead of the CPU id. If there are hardware issues with a CPU, they're likely to affect both threads. Seeing to different "CPUs" in an SMT environment might tempt some folks to think it's not a core-level hardware issue.
If it's as trivial as:
printk(KERN_CONT " on cpu/core %d/%d", raw_smp_processor_id(), topology_core_id(raw_smp_processor_id()));
it would be handy. But, it's also not hard to look at 10 segfaults, see that they happened only on 2 CPUs and realize that hyperthreading is enabled.
Either way, this patch moves things in the right direction, so:
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
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