Messages in this thread | | | Date | Fri, 27 Apr 2018 01:21:52 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc fallback options |
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On Thu, Apr 26, 2018 at 05:50:20PM -0400, Mikulas Patocka wrote: > How is the user or developer supposed to learn about this option, if > he gets no crash at all?
Look in /sys/kernel/debug/fail* ? That actually lets you filter by module, process etc.
I think this patch conflates two things:
1. Make kvmalloc use the vmalloc path. This seems a bit narrow. What is special about kvmalloc? IMHO nothing - it's yet another user of __GFP_NORETRY or __GFP_RETRY_MAYFAIL. As any such user, it either recovers correctly or not. So IMHO it's just a case of making __GFP_NORETRY, __GFP_RETRY_MAYFAIL, or both fail once in a while. Seems like a better extension to me than focusing on vmalloc. I think you will find more bugs this way.
2. Ability to control this from a separate config option.
It's still not that clear to me why is this such a hard requirement. If a distro wants to force specific boot time options, why isn't CONFIG_CMDLINE sufficient?
But assuming it's important to control this kind of fault injection to be controlled from a dedicated menuconfig option, why not the rest of faults?
IMHO if you split 1/2 up, and generalize, the path upstream will be much smoother.
Hope this helps.
-- MST
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