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author | David P <megver83@parabola.nu> | 2022-06-22 17:37:44 -0400 |
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committer | David P <megver83@parabola.nu> | 2022-06-22 17:37:44 -0400 |
commit | 574951475cda65ca7dd634ba6d6ddeee58596c35 (patch) | |
tree | 439e1339bfc7ba480c3596215de555ad1177a428 /libre/linux-libre/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch | |
parent | 57dc25502eca1193d7d852c3d1545fe5067efafa (diff) | |
download | abslibre-574951475cda65ca7dd634ba6d6ddeee58596c35.tar.gz abslibre-574951475cda65ca7dd634ba6d6ddeee58596c35.tar.bz2 abslibre-574951475cda65ca7dd634ba6d6ddeee58596c35.zip |
updpkg: libre/linux-libre 5.18.5-1
Signed-off-by: David P <megver83@parabola.nu>
Diffstat (limited to 'libre/linux-libre/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch')
-rw-r--r-- | libre/linux-libre/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch | 119 |
1 files changed, 0 insertions, 119 deletions
diff --git a/libre/linux-libre/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch b/libre/linux-libre/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch deleted file mode 100644 index 7d67087ac..000000000 --- a/libre/linux-libre/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch +++ /dev/null @@ -1,119 +0,0 @@ -From e4bc9f7cc85243a32f100925bde5f48c23bfe1de Mon Sep 17 00:00:00 2001 -From: Frederic Weisbecker <frederic@kernel.org> -Date: Tue, 8 Feb 2022 17:16:34 +0100 -Subject: [PATCH 5/7] tick/rcu: Stop allowing RCU_SOFTIRQ in idle - -RCU_SOFTIRQ used to be special in that it could be raised on purpose -within the idle path to prevent from stopping the tick. Some code still -prevents from unnecessary warnings related to this specific behaviour -while entering in dynticks-idle mode. - -However the nohz layout has changed quite a bit in ten years, and the -removal of CONFIG_RCU_FAST_NO_HZ has been the final straw to this -safe-conduct. Now the RCU_SOFTIRQ vector is expected to be raised from -sane places. - -A remaining corner case is admitted though when the vector is invoked -in fragile hotplug path. - -Signed-off-by: Frederic Weisbecker <frederic@kernel.org> -Cc: Thomas Gleixner <tglx@linutronix.de> -Cc: Peter Zijlstra <peterz@infradead.org> -Cc: Paul E. McKenney <paulmck@kernel.org> -Cc: Paul Menzel <pmenzel@molgen.mpg.de> ---- - include/linux/interrupt.h | 8 ++++++- - kernel/time/tick-sched.c | 50 +++++++++++++++++++++++++++++++-------- - 2 files changed, 47 insertions(+), 11 deletions(-) - -diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h -index 9367f1cb2e3c..9613326d2f8a 100644 ---- a/include/linux/interrupt.h -+++ b/include/linux/interrupt.h -@@ -579,7 +579,13 @@ enum - NR_SOFTIRQS - }; - --#define SOFTIRQ_STOP_IDLE_MASK (~(1 << RCU_SOFTIRQ)) -+/* -+ * Ignoring the RCU vector after ksoftirqd is parked is fine -+ * because: -+ * 1) rcutree_migrate_callbacks() takes care of the queue. -+ * 2) rcu_report_dead() reports the final quiescent states. -+ */ -+#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(RCU_SOFTIRQ)) - - /* map softirq index to softirq name. update 'softirq_to_name' in - * kernel/softirq.c when adding a new softirq. -diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c -index 4c62fa0f70f1..3506f6ed790c 100644 ---- a/kernel/time/tick-sched.c -+++ b/kernel/time/tick-sched.c -@@ -999,6 +999,45 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts) - __tick_nohz_full_update_tick(ts, ktime_get()); - } - -+/* -+ * A pending softirq outside an IRQ (or softirq disabled section) context -+ * should be waiting for ksoftirqd to handle it. Therefore we shouldn't -+ * reach here due to the need_resched() early check in can_stop_idle_tick(). -+ * -+ * However if we are between CPUHP_AP_SMPBOOT_THREADS and CPU_TEARDOWN_CPU on the -+ * cpu_down() process, softirqs can still be raised while ksoftirqd is parked, -+ * triggering the below since wakep_softirqd() is ignored. -+ * -+ */ -+static bool report_idle_softirq(void) -+{ -+ static int ratelimit; -+ unsigned int pending = local_softirq_pending(); -+ -+ if (likely(!pending)) -+ return false; -+ -+ /* Some softirqs claim to be safe against hotplug and ksoftirqd parking */ -+ if (!cpu_active(smp_processor_id())) { -+ pending &= ~SOFTIRQ_HOTPLUG_SAFE_MASK; -+ if (!pending) -+ return false; -+ } -+ -+ if (ratelimit < 10) -+ return false; -+ -+ /* On RT, softirqs handling may be waiting on some lock */ -+ if (!local_bh_blocked()) -+ return false; -+ -+ pr_warn("NOHZ tick-stop error: local softirq work is pending, handler #%02x!!!\n", -+ pending); -+ ratelimit++; -+ -+ return true; -+} -+ - static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) - { - /* -@@ -1025,17 +1064,8 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) - if (need_resched()) - return false; - -- if (unlikely(local_softirq_pending())) { -- static int ratelimit; -- -- if (ratelimit < 10 && !local_bh_blocked() && -- (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { -- pr_warn("NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #%02x!!!\n", -- (unsigned int) local_softirq_pending()); -- ratelimit++; -- } -+ if (unlikely(report_idle_softirq())) - return false; -- } - - if (tick_nohz_full_enabled()) { - /* --- -2.36.1 - |