[PATCH 0/2] sched/psi: Preserve RT poll notifications

[Hui Su]

Privileged RT trigger registration can consume pressure accounting before
existing triggers evaluate it. A separate worker shutdown path can leave a
rate-limited event pending after active polling expires.

Patch 1 preserves registration-time pressure changes for existing triggers
and advances the consumed total after due evaluation.

Patch 2 derives pending notification deadlines from the trigger list instead
of storing a duplicate deadline in psi_group. It preserves pending trigger
windows, resumes active polling when watched pressure returns, and lets the
worker return to idle after the notification is delivered.

Testing:
- x86_64 KASAN/lockdep KUnit: candidate PSI 10/10 passed; baseline PSI had
  1/10 pass and 9 candidate-dependent failures. Refcount tests passed 4/4
  on both sides; no KASAN report.
- QEMU cgroup PSI_POLL: baseline pressure qualified but the second long event
  was absent by 2500 ms; the worker log showed pending=1 and timer_pending=0.
  Candidate delivered the second event after 2004.4 ms; pending cleared and
  the worker returned to idle. Both runs had zero quiet-period pressure and
  no unexpected third event.

Hui Su (2):
  sched/psi: Preserve pressure accounting across RT trigger registration
  sched/psi: Deliver pending RT poll events after polling expires

 include/linux/psi_types.h |   1 +
 kernel/sched/psi.c        | 206 +++++++++++++++++++++++++++++---------
 2 files changed, 157 insertions(+), 50 deletions(-)


base-commit: b99b7f60c5b473d374c68b53753153b4aa9e0702
-- 
2.55.0