Re: FAILED: patch "[PATCH] sched/fair: Fix unthrottle_cfs_rq() for leaf_cfs_rq list" failed to apply to 5.4-stable tree

[Vincent Guittot <vincent.guittot@linaro.org>]

On Sun, 6 Dec 2020 at 12:47, Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Sun, Dec 06, 2020 at 12:25:12PM +0100, Vincent Guittot wrote:
> > On Sun, 6 Dec 2020 at 10:56, Greg KH <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Mon, May 25, 2020 at 07:27:09PM +0200, Vincent Guittot wrote:
> > > > Le lundi 25 mai 2020 à 16:42:49 (+0200), gregkh@linuxfoundation.org a écrit :
> > > > >
> > > > > The patch below does not apply to the 5.4-stable tree.
> > > > > If someone wants it applied there, or to any other stable or longterm
> > > > > tree, then please email the backport, including the original git commit
> > > > > id to <stable@vger.kernel.org>.
> > > >
> > > > This patch needs  commit
> > > >     b34cb07dde7c ("sched/fair: Fix enqueue_task_fair() warning some more")
> > > > to be applied first. But then, it will not apply. The backport is :
> > > >
> > > > [ Upstream commit 39f23ce07b9355d05a64ae303ce20d1c4b92b957 upstream ]
> > > >
> > > > Although not exactly identical, unthrottle_cfs_rq() and enqueue_task_fair()
> > > > are quite close and follow the same sequence for enqueuing an entity in the
> > > > cfs hierarchy. Modify unthrottle_cfs_rq() to use the same pattern as
> > > > enqueue_task_fair(). This fixes a problem already faced with the latter and
> > > > add an optimization in the last for_each_sched_entity loop.
> > > >
> > > > Fixes: fe61468b2cb (sched/fair: Fix enqueue_task_fair warning)
> > > > Reported-by Tao Zhou <zohooouoto@zoho.com.cn>
> > > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > > > Reviewed-by: Phil Auld <pauld@redhat.com>
> > > > Reviewed-by: Ben Segall <bsegall@google.com>
> > > > Link: https://lkml.kernel.org/r/20200513135528.4742-1-vincent.guittot@linaro.org
> > > > ---
> > > >  kernel/sched/fair.c | 36 ++++++++++++++++++++++++++++--------
> > > >  1 file changed, 28 insertions(+), 8 deletions(-)
> > >
> > > This patch doesn't apply to the 5.4.y tree at all.  Can someone please
> > > provide a working backport?
> >
> > It seems that commit b34cb07dde7c ("sched/fair: Fix
> > enqueue_task_fair() warning some more") has already been applied back
> > in May. But then, I'm able to apply this patch on top of
> > v5.4.y/v5.4.81
> >
>
> What is "this patch" here?  I tried to apply 39f23ce07b93 ("sched/fair:
> Fix unthrottle_cfs_rq() for leaf_cfs_rq list") directly to the 5.4 tree
> and it too did not apply.

commit 39f23ce07b93 ("sched/fair: Fix unthrottle_cfs_rq() for
leaf_cfs_rq list") can't apply because there are several changes which
are not fixes which have been applied since v5.4 on the same code.

This patch is the backport on v5.4 of the commit 39f23ce07b93

>
> confused,
>
> greg k-h