Re: [PATCH] mm/memcontrol: update documentation about invoking oom killer

[Konstantin Khlebnikov]

On 02/11/2019 19.02, Damian Tometzki wrote:
> On Sat, 02. Nov 18:16, Konstantin Khlebnikov wrote:
> > Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the
> > charge path") memcg invokes oom killer not only for user page-faults.
> > This means 0-order allocation will either succeed or task get killed.
> >
> > Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills")
> > Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
> > ---
> >   Documentation/admin-guide/cgroup-v2.rst |    9 +++++++--
> >   1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> > index 5361ebec3361..eb47815e137b 100644
> > --- a/Documentation/admin-guide/cgroup-v2.rst
> > +++ b/Documentation/admin-guide/cgroup-v2.rst
> > @@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back.
> >   
> >   		Failed allocation in its turn could be returned into
> >   		userspace as -ENOMEM or silently ignored in cases like
> > -		disk readahead.  For now OOM in memory cgroup kills
> > -		tasks iff shortage has happened inside page fault.
> > +		disk readahead.
> > +
> > +		Before 4.19 OOM in memory cgroup killed tasks iff
> Hello Konstantin,
>
> iff --> if :-)

This "iff" is shortened "if and only if".
https://en.wikipedia.org/wiki/If_and_only_if

> Best regards
> Damian
>
>
> > +		shortage has happened inside page fault, random
> > +		syscall may fail with ENOMEM or EFAULT. Since 4.19
> > +		failed memory cgroup allocation invokes oom killer and
> > +		keeps retrying until it succeeds.
> >   
> >   		This event is not raised if the OOM killer is not
> >   		considered as an option, e.g. for failed high-order