The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7962c0896429af2a0e00ec6bc15d992536453b2d Mon Sep 17 00:00:00 2001 From: Helge Deller deller@gmx.de Date: Sat, 7 May 2022 15:32:38 +0200 Subject: [PATCH] Revert "parisc: Mark sched_clock unstable only if clocks are not syncronized"

This reverts commit d97180ad68bdb7ee10f327205a649bc2f558741d.

It triggers RCU stalls at boot with a 32-bit kernel.

Signed-off-by: Helge Deller deller@gmx.de Noticed-by: John David Anglin dave.anglin@bell.net Cc: stable@vger.kernel.org # v5.15+

diff --git a/arch/parisc/kernel/setup.c b/arch/parisc/kernel/setup.c index b91cb45ffd4e..f005ddedb50e 100644 --- a/arch/parisc/kernel/setup.c +++ b/arch/parisc/kernel/setup.c @@ -161,6 +161,8 @@ void __init setup_arch(char **cmdline_p) #ifdef CONFIG_PA11 dma_ops_init(); #endif + + clear_sched_clock_stable(); }

/* diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c index 95ee9e1a364b..19c31a72fe76 100644 --- a/arch/parisc/kernel/time.c +++ b/arch/parisc/kernel/time.c @@ -267,9 +267,6 @@ static int __init init_cr16_clocksource(void) (cpu0_loc == per_cpu(cpu_data, cpu).cpu_loc)) continue;

- /* mark sched_clock unstable */ - clear_sched_clock_stable(); - clocksource_cr16.name = "cr16_unstable"; clocksource_cr16.flags = CLOCK_SOURCE_UNSTABLE; clocksource_cr16.rating = 0; @@ -277,6 +274,10 @@ static int __init init_cr16_clocksource(void) } }

+ /* XXX: We may want to mark sched_clock stable here if cr16 clocks are + * in sync: + * (clocksource_cr16.flags == CLOCK_SOURCE_IS_CONTINUOUS) */ + /* register at clocksource framework */ clocksource_register_hz(&clocksource_cr16, 100 * PAGE0->mem_10msec);