Messages in this thread Patch in this message | | | From | Xuewen Yan <> | Date | Tue, 12 Dec 2023 10:51:05 +0800 | Subject | Re: [PATCH] sched/eevdf: Avoid NULL in pick_eevdf |
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Hi Abel
On Mon, Nov 20, 2023 at 4:49 PM Abel Wu <wuyun.abel@bytedance.com> wrote: > > Hi Xuewen, the pick part has been re-worked, would you please re-test > with the newest branch? > > Thanks, > Abel > > https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/?h=sched%2Fcore
These patches would be merged into 6.6? If not, the pr_err also has a deadlock. And should be changed to printk_deferred.
954 static struct sched_entity *pick_eevdf(struct cfs_rq *cfs_rq) 955 { 956 struct sched_entity *se = __pick_eevdf(cfs_rq); 957 958 if (!se) { 959 struct sched_entity *left = __pick_first_entity(cfs_rq); 960 if (left) { 961 pr_err("EEVDF scheduling fail, picking leftmost\n"); <<<< 962 return left; 963 } 964 } 965 966 return se; 967 }
> > On 11/20/23 3:38 PM, Xuewen Yan Wrote: > > Now in pick_eevdf function, add the pick_first_entity to prevent > > picking null when using eevdf, however, the leftmost may be null. > > As a result, it would cause oops because the se is NULL. > > > > Fix this by compare the curr and left, if the left is null, set > > the se be curr. > > > > Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy") > > Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> > > --- > > kernel/sched/fair.c | 18 +++++++++++++++++- > > 1 file changed, 17 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index d7a3c63a2171..10916f6778ac 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -951,12 +951,28 @@ static struct sched_entity *__pick_eevdf(struct cfs_rq *cfs_rq) > > return NULL; > > } > > > > +/* Just simply choose the se with the smallest vruntime */ > > +static struct sched_entity *__pick_cfs(struct cfs_rq *cfs_rq) > > +{ > > + struct sched_entity *curr = cfs_rq->curr; > > + struct sched_entity *left = __pick_first_entity(cfs_rq); > > + > > + /* > > + * If curr is set we have to see if its left of the leftmost entity > > + * still in the tree, provided there was anything in the tree at all. > > + */ > > + if (!left || (curr && entity_before(curr, left))) > > + left = curr; > > + > > + return left; > > +} > > + > > static struct sched_entity *pick_eevdf(struct cfs_rq *cfs_rq) > > { > > struct sched_entity *se = __pick_eevdf(cfs_rq); > > > > if (!se) { > > - struct sched_entity *left = __pick_first_entity(cfs_rq); > > + struct sched_entity *left = __pick_cfs(cfs_rq); > > if (left) { > > pr_err("EEVDF scheduling fail, picking leftmost\n"); > > return left;
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