diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-05-20 10:15:30 -0500 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-05-20 10:15:30 -0500 |
| commit | df685633c3dbc67441cc86f1c3fee58de4652ba2 (patch) | |
| tree | 099f075d1cdb4c3443842f697a564f971d2bafc5 | |
| parent | e312f536f647156ac55e2f12d021cf887af274aa (diff) | |
| parent | 593889c401426004bd0ea0f6d4fcece728b03420 (diff) | |
Merge tag 'rcu-fixes.v7.1-20260519a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux
Pull RCU fixes from Boqun Feng:
"Fix a regression introduced by commit 61bbcfb50514 ("srcu: Push
srcu_node allocation to GP when non-preemptible").
SRCU may queue works on CPUs that are "possible" but never have been
online. In such a case, the work callbacks may not be executed until
the corresponding CPU gets online, and as the callbacks accumulates,
workqueue lockups will fire.
Fix this by avoiding queuing works on CPUs that have never been
online"
* tag 'rcu-fixes.v7.1-20260519a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux:
srcu: Don't queue workqueue handlers to never-online CPUs
| -rw-r--r-- | kernel/rcu/srcutree.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 0d01cd8c4b4a..7c2f7cc131f7 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -897,11 +897,9 @@ static void srcu_schedule_cbs_snp(struct srcu_struct *ssp, struct srcu_node *snp { int cpu; - for (cpu = snp->grplo; cpu <= snp->grphi; cpu++) { - if (!(mask & (1UL << (cpu - snp->grplo)))) - continue; - srcu_schedule_cbs_sdp(per_cpu_ptr(ssp->sda, cpu), delay); - } + for (cpu = snp->grplo; cpu <= snp->grphi; cpu++) + if ((mask & (1UL << (cpu - snp->grplo))) && rcu_cpu_beenfullyonline(cpu)) + srcu_schedule_cbs_sdp(per_cpu_ptr(ssp->sda, cpu), delay); } /* @@ -1322,7 +1320,9 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp, */ idx = __srcu_read_lock_nmisafe(ssp); ss_state = smp_load_acquire(&ssp->srcu_sup->srcu_size_state); - if (ss_state < SRCU_SIZE_WAIT_CALL) + // If !rcu_cpu_beenfullyonline(), interrupts are still disabled, + // so no migration is possible in either direction from this CPU. + if (ss_state < SRCU_SIZE_WAIT_CALL || !rcu_cpu_beenfullyonline(raw_smp_processor_id())) sdp = per_cpu_ptr(ssp->sda, get_boot_cpu_id()); else sdp = raw_cpu_ptr(ssp->sda); |