From: Petr Mladek <pmladek@suse.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Laurence Oberman <loberman@redhat.com>,
Vincent Whitchurch <vincent.whitchurch@axis.com>,
Michal Hocko <mhocko@suse.com>,
linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>
Subject: [PATCH v2 7/7] Test softlockup
Date: Thu, 11 Mar 2021 13:21:30 +0100 [thread overview]
Message-ID: <20210311122130.6788-8-pmladek@suse.com> (raw)
In-Reply-To: <20210311122130.6788-1-pmladek@suse.com>
Trigger busy loop by:
$> cat /proc/version
Stop the busy loop by:
$> cat /proc/consoles
The code also shows the first touch*watchdog() function that hides
softlockup on a "well known" location.
Signed-off-by: Petr Mladek <pmladek@suse.com>
---
fs/proc/consoles.c | 5 +++++
fs/proc/version.c | 7 +++++++
2 files changed, 12 insertions(+)
diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
index dfe6ce3505ce..213c0a209a7c 100644
--- a/fs/proc/consoles.c
+++ b/fs/proc/consoles.c
@@ -9,6 +9,8 @@
#include <linux/seq_file.h>
#include <linux/tty_driver.h>
+extern volatile bool proc_version_wait;
+
/*
* This is handler for /proc/consoles
*/
@@ -30,6 +32,9 @@ static int show_console_dev(struct seq_file *m, void *v)
unsigned int a;
dev_t dev = 0;
+ printk("%s: Going to break /proc/version infinite loop\n", __func__);
+ proc_version_wait = false;
+
if (con->device) {
const struct tty_driver *driver;
int index;
diff --git a/fs/proc/version.c b/fs/proc/version.c
index b449f186577f..15ec6a502589 100644
--- a/fs/proc/version.c
+++ b/fs/proc/version.c
@@ -6,8 +6,15 @@
#include <linux/seq_file.h>
#include <linux/utsname.h>
+volatile bool proc_version_wait;
+
static int version_proc_show(struct seq_file *m, void *v)
{
+ printk("%s: Going to wait until stopped\n", __func__);
+ proc_version_wait = true;
+ while (proc_version_wait)
+ cpu_relax();
+
seq_printf(m, linux_proc_banner,
utsname()->sysname,
utsname()->release,
--
2.26.2
next prev parent reply other threads:[~2021-03-11 12:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-11 12:21 [PATCH v2 0/7] watchdog/softlockup: Report overall time and some cleanup Petr Mladek
2021-03-11 12:21 ` [PATCH v2 1/7] watchdog: Rename __touch_watchdog() to a better descriptive name Petr Mladek
2021-03-11 12:21 ` [PATCH v2 2/7] watchdog: Explicitly update timestamp when reporting softlockup Petr Mladek
2021-03-11 12:21 ` [PATCH v2 3/7] watchdog/softlockup: Report the overall time of softlockups Petr Mladek
2021-03-11 12:21 ` [PATCH v2 4/7] watchdog/softlockup: Remove logic that tried to prevent repeated reports Petr Mladek
2021-03-11 12:21 ` [PATCH v2 5/7] watchdog: Fix barriers when printing backtraces from all CPUs Petr Mladek
2021-03-11 12:21 ` [PATCH v2 6/7] watchdog: Cleanup handling of false positives Petr Mladek
2021-03-11 12:21 ` Petr Mladek [this message]
2021-03-15 14:04 ` c928e9b143: BUG:soft_lockup-CPU##stuck_for#s![perf:#] kernel test robot
2021-03-16 11:43 ` Petr Mladek
-- strict thread matches above, loose matches on Subject: below --
2020-12-10 16:00 [PATCH v2 0/7] watchdog/softlockup: Report overall time and some cleanup Petr Mladek
2020-12-10 16:00 ` [PATCH v2 7/7] Test softlockup Petr Mladek
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