diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2023-08-28 13:46:41 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2023-08-28 13:46:41 -0700 |
| commit | b324696dce7a5b1be11c16cbba6ac6643dadd364 (patch) | |
| tree | 49abec46d7fdce18270fe8be544697b809fb7cb0 | |
| parent | 6ae0c157658b26e78eb30b50939ce3dfb794d21f (diff) | |
| parent | 0d3a00b370424f5f1b9fd037bc8a4a3e7cbf0939 (diff) | |
Merge tag 'csd-lock.2023.07.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull CSD lock updates from Paul McKenney:
"This series reduces the number of stack traces dumped during CSD-lock
debugging. This helps to avoid console overrun on systems with large
numbers of CPUs"
* tag 'csd-lock.2023.07.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
smp: Reduce NMI traffic from CSD waiters to CSD destination
smp: Reduce logging due to dump_stack of CSD waiters
| -rw-r--r-- | kernel/smp.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index 385179dae360..8455a53465af 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -46,6 +46,8 @@ static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data); static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); +static DEFINE_PER_CPU(atomic_t, trigger_backtrace) = ATOMIC_INIT(1); + static void __flush_smp_call_function_queue(bool warn_cpu_offline); int smpcfd_prepare_cpu(unsigned int cpu) @@ -253,13 +255,15 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 * *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request"); } if (cpu >= 0) { - dump_cpu_task(cpu); + if (atomic_cmpxchg_acquire(&per_cpu(trigger_backtrace, cpu), 1, 0)) + dump_cpu_task(cpu); if (!cpu_cur_csd) { pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu); arch_send_call_function_single_ipi(cpu); } } - dump_stack(); + if (firsttime) + dump_stack(); *ts1 = ts2; return false; @@ -433,9 +437,14 @@ static void __flush_smp_call_function_queue(bool warn_cpu_offline) struct llist_node *entry, *prev; struct llist_head *head; static bool warned; + atomic_t *tbt; lockdep_assert_irqs_disabled(); + /* Allow waiters to send backtrace NMI from here onwards */ + tbt = this_cpu_ptr(&trigger_backtrace); + atomic_set_release(tbt, 1); + head = this_cpu_ptr(&call_single_queue); entry = llist_del_all(head); entry = llist_reverse_order(entry); |