Re: bug-introducing patches

[Sasha Levin]

On Wed, May 02, 2018 at 05:32:37PM +0200, Geert Uytterhoeven wrote:
>Hi Sasha,
>
>On Tue, May 1, 2018 at 6:38 PM, Sasha Levin
><Alexander.Levin@xxxxxxxxxxxxx> wrote:
>> Working on AUTOSEL, it became even more obvious to me how difficult it is for a
>> patch to get a proper review. Maintainers found it difficult to keep up with
>> the upstream work for their subsystem, and reviewing additional -stable patches
>> put even more load on them which some suggested would be more than what they
>> can handle.
>
>Thanks for your work!
>
>>  - For some reason, the odds of a -rc commit to be targetted for -stable is
>>    over 20%, while for merge window commits it's about 3%. I can't quite
>> explain why that happens, but this would suggest that -rc commits end up
>> hurting -stable pretty badly.
>
>Aren't more -rc commits targeted for -stable because they are bugfixes?
>Ideally, new features are supposed to be merged during the merge window,
>while -rc commits fix bugs.

new features can only be merged during a merge window, bug fixes can 
be merged at any point.

>So they can be categorized like:
>  1. Plain -rc commits,

What's this exactly? -rc commits are only supposed to fix bugs.

>  2. -rc commits fixing a bug:
>       a. in the same release cycle,
>       b. in a previous release.
>
>2a assumes the bug was backported to -stable, too, doesn't it?

Bug fixes for features introduced in that release cycle won't be
backported to stable.

>Do you have statistics for which categories are most buggy?

I haven't broken it down to subsystems for a few reasons:

 - My dataset is based on the Fixes: tag, some subsystems use it less
   than others.
 - Maintainers change, so even if one subsystem is being awesome about
   it today, it might not be the case in a year.
 - I don't really want to point fingers at a particular subsystem, I
   think that this is an issue at the kernel level.