Re: [PATCH] mm,vmscan: Mark register_shrinker() as __must_check

[Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>]

Michal Hocko wrote:
> On Thu 23-11-17 18:56:53, Tetsuo Handa wrote:
> > Paolo Bonzini wrote:
> > > On 23/11/2017 07:34, Tetsuo Handa wrote:
> > > >> Just fix the numa aware shrinkers, as they are the only ones that
> > > >> will have this problem. There are only 6 of them, and only the 3
> > > >> that existed at the time that register_shrinker() was changed to
> > > >> return an error fail to check for an error. i.e. the superblock
> > > >> shrinker, the XFS dquot shrinker and the XFS buffer cache shrinker.
> > > >
> > > > You are assuming the "too small to fail" memory-allocation rule
> > > > by ignoring that this problem is caused by fault injection.
> > > 
> > > Fault injection should also obey the too small to fail rule, at least by
> > > default.
> > > 
> > 
> > Pardon? Most allocation requests in the kernel are <= 32KB.
> > Such change makes fault injection useless. ;-)
> 
> Agreed! All we need is to fix the shrinker registration callers. It is
> that simple. The rest is just a distraction.
> 

Which coverage (all register_shrinker() callers or only SHRINKER_NUMA_AWARE
callers) are you talking about? If the former, keeping __must_check is OK.
If the latter, it will not avoid future oops reports with fault injection.

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