lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 1 Nov 2017 11:34:14 -0700 From: Guenter Roeck <linux@...ck-us.net> To: Don Zickus <dzickus@...hat.com> Cc: Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>, linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org> Subject: Re: Crashes in perf_event_ctx_lock_nested On Wed, Nov 01, 2017 at 02:11:27PM -0400, Don Zickus wrote: > > > > Maybe watchdog_cpus needs to be atomic ? > > I switched it to atomic and it solves that problem. The functionality isn't > broken currently, just the informational message. > > Patch attached to try. > Tested-by: Guenter Roeck <linux@...ck-us.net> Thanks! Guenter > Cheers, > Don > > ---8<-------------- > > diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c > index a7f137c1933a..8ee4da223b35 100644 > --- a/kernel/watchdog_hld.c > +++ b/kernel/watchdog_hld.c > @@ -14,6 +14,7 @@ > #include <linux/nmi.h> > #include <linux/module.h> > #include <linux/sched/debug.h> > +#include <linux/atomic.h> Alphabetical order, maybe ? > > #include <asm/irq_regs.h> > #include <linux/perf_event.h> > @@ -25,7 +26,7 @@ static DEFINE_PER_CPU(struct perf_event *, dead_event); > static struct cpumask dead_events_mask; > > static unsigned long hardlockup_allcpu_dumped; > -static unsigned int watchdog_cpus; > +static atomic_t watchdog_cpus = ATOMIC_INIT(0); > > void arch_touch_nmi_watchdog(void) > { > @@ -189,7 +190,8 @@ void hardlockup_detector_perf_enable(void) > if (hardlockup_detector_event_create()) > return; > > - if (!watchdog_cpus++) > + /* use original value for check */ > + if (!atomic_fetch_inc(&watchdog_cpus)) > pr_info("Enabled. Permanently consumes one hw-PMU counter.\n"); > > perf_event_enable(this_cpu_read(watchdog_ev)); > @@ -207,7 +209,7 @@ void hardlockup_detector_perf_disable(void) > this_cpu_write(watchdog_ev, NULL); > this_cpu_write(dead_event, event); > cpumask_set_cpu(smp_processor_id(), &dead_events_mask); > - watchdog_cpus--; > + atomic_dec(&watchdog_cpus); > } > } >
Powered by blists - more mailing lists