6.15-stable review patch. If anyone has any objections, please let me know.
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From: Juri Lelli juri.lelli@redhat.com
[ Upstream commit fcc9276c4d331cd1fe9319d793e80b02e09727f5 ]
dl_clear_root_domain() doesn't take into account the fact that per-rq extra_bw variables retain values computed before root domain changes, resulting in broken accounting.
Fix it by resetting extra_bw to max_bw before restoring back dl-servers contributions.
Fixes: 2ff899e351643 ("sched/deadline: Rebuild root domain accounting after every update") Reported-by: Marcel Ziswiler marcel.ziswiler@codethink.co.uk Signed-off-by: Juri Lelli juri.lelli@redhat.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Tested-by: Marcel Ziswiler marcel.ziswiler@codethink.co.uk # nuc & rock5b Link: https://lore.kernel.org/r/20250627115118.438797-3-juri.lelli@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/deadline.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index ef5b5c045769..135580a41e14 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -3007,7 +3007,14 @@ void dl_clear_root_domain(struct root_domain *rd) int i;
guard(raw_spinlock_irqsave)(&rd->dl_bw.lock); + + /* + * Reset total_bw to zero and extra_bw to max_bw so that next + * loop will add dl-servers contributions back properly, + */ rd->dl_bw.total_bw = 0; + for_each_cpu(i, rd->span) + cpu_rq(i)->dl.extra_bw = cpu_rq(i)->dl.max_bw;
/* * dl_servers are not tasks. Since dl_add_task_root_domain ignores