Re: [PATCH -tip v3 0/7] kprobes/x86: Preempt related enhancements

From: Alexei Starovoitov
Date: Thu Sep 21 2017 - 18:01:27 EST

On 9/19/17 2:58 AM, Masami Hiramatsu wrote:

Here is the 3rd version of the series to improve preempt
related behavior in kprobes/x86. This actually includes
many enhancements/fixes from the 2nd version, which is

With the previous patch, lkp-bot reported that an issue
( ) and I couldn't
reproduce it. However, I found a suspicious bug and fixed
it ([2/7]).

Also, while I was checking the correct condition for
*probe handlers in Documentation/kprobes.txt, I also
found that current implementations for ftrace-based kprobe
and optprobe were mis-reading the document.
From the document, handlers must be run with preempt-
disabled, but interrupt disabling is not guaranteed.
So in the middle of this series, patches ([4/7],[5/7],
[6/7]) adding preempt-disabling and removing irq-disabling.

And at last, I placed the original patch (Enable optprobe

The others are just for making sure this fix works well.
- [1/7] is just adding preemptible checker in kprobe
smake tests so that we can easily find mistake.
- [3/7] is adding an assert if user tries to change
execution path in optprobe, which is obviously
prohibited in the document (there also be how to
avoid it.)

all patches look great to me.
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>