diff options
| author | Daniel Axtens <[email protected]> | 2017-05-11 06:11:39 +1000 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2017-06-20 12:26:52 +0200 |
| commit | c5ae366e12b2bd56fc7d7e9d484836bec9ddc110 (patch) | |
| tree | 1692a39f932899f7d3cc5fab6c94fe71b9e9803b /kernel | |
| parent | 6d3aed3d8a0573d0a6eb1160ccd0a0713f4dbc2f (diff) | |
sched/fair: WARN() and refuse to set buddy when !se->on_rq
If we set a next or last buddy for a se that is not on_rq, we will
end up taking a NULL pointer dereference in wakeup_preempt_entity
via pick_next_task_fair.
Detect when we would be about to do that, throw a warning and
then refuse to actually set it.
This has been suggested at least twice:
https://marc.info/?l=linux-kernel&m=146651668921468&w=2
https://lkml.org/lkml/2016/6/16/663
I recently had to debug a problem with these (we hadn't backported
Konstantin's patches in this area) and this would have saved a lot
of time/pain.
Just do it.
Signed-off-by: Daniel Axtens <[email protected]>
Cc: Ben Segall <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 396bca9c7996..cb3a3da7089f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6164,8 +6164,11 @@ static void set_last_buddy(struct sched_entity *se) if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) return; - for_each_sched_entity(se) + for_each_sched_entity(se) { + if (SCHED_WARN_ON(!se->on_rq)) + return; cfs_rq_of(se)->last = se; + } } static void set_next_buddy(struct sched_entity *se) @@ -6173,8 +6176,11 @@ static void set_next_buddy(struct sched_entity *se) if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) return; - for_each_sched_entity(se) + for_each_sched_entity(se) { + if (SCHED_WARN_ON(!se->on_rq)) + return; cfs_rq_of(se)->next = se; + } } static void set_skip_buddy(struct sched_entity *se) |