6.15-stable review patch. If anyone has any objections, please let me know.
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From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 99b773d720aeea1ef2170dce5fcfa80649e26b78 ]
With the seqcount moved out of the group into a global psi_seq, re-initializing the seqcount on group creation is causing seqcount corruption.
Fixes: 570c8efd5eb7 ("sched/psi: Optimize psi_group_change() cpu_clock() usage") Reported-by: Chris Mason clm@meta.com Suggested-by: Beata Michalska beata.michalska@arm.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/psi.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index c62f4316a2b9..e0ad56b26171 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -172,7 +172,7 @@ struct psi_group psi_system = { .pcpu = &system_group_pcpu, };
-static DEFINE_PER_CPU(seqcount_t, psi_seq); +static DEFINE_PER_CPU(seqcount_t, psi_seq) = SEQCNT_ZERO(psi_seq);
static inline void psi_write_begin(int cpu) { @@ -200,11 +200,7 @@ static void poll_timer_fn(struct timer_list *t);
static void group_init(struct psi_group *group) { - int cpu; - group->enabled = true; - for_each_possible_cpu(cpu) - seqcount_init(per_cpu_ptr(&psi_seq, cpu)); group->avg_last_update = sched_clock(); group->avg_next_update = group->avg_last_update + psi_period; mutex_init(&group->avgs_lock);