[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <bd5feeb3-bc44-d4d2-7708-eea9243b49a4@gmail.com>
Date: Fri, 4 Aug 2023 13:07:41 +0200
From: Rafał Miłecki <zajec5@...il.com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
Waiman Long <longman@...hat.com>,
Boqun Feng <boqun.feng@...il.com>,
Russell King <linux@...linux.org.uk>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Florian Fainelli <f.fainelli@...il.com>,
linux-clk@...r.kernel.org,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Network Development <netdev@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: OpenWrt Development List <openwrt-devel@...ts.openwrt.org>,
bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: ARM board lockups/hangs triggered by locks and mutexes
On 2.08.2023 00:10, Rafał Miłecki wrote:
> Unfortunately enabling *any* of following options:
> CONFIG_DEBUG_RT_MUTEXES=y
> CONFIG_DEBUG_SPINLOCK=y
> CONFIG_DEBUG_MUTEXES=y
> seems to make locksup/hangs go away. I tried for few hours.
I decided to find out why enabling CONFIG_DEBUG_MUTEXES "fixes" kernel /
device stability for me. I tried enabling manually code that normally
hides behind the #ifdev CONFIG_DEBUG_MUTEXES.
Attached to this e-mail is a small patch that is enough to make my
kernel stable (mutex-fix-bcm53573.diff).
#####
It's not what's the most interesting thought. What really doesn't make
sense anymore is that below diff (on top of attached one) brings back
hangs/lockups.
I triple checked that. Dropping a single unused function breaks kernel /
device stability on BCM53573!
AFAIK the only thing below diff actually affects is location of symbols
(I actually verified that by comparing System.map before and after -
over 22'000 of relocated symbols).
Can some unfortunate location of symbols cause those hangs/lockups?
diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c
index 4fe40910f..c440222a4 100644
--- a/kernel/locking/mutex-debug.c
+++ b/kernel/locking/mutex-debug.c
@@ -34,6 +34,8 @@ void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
INIT_LIST_HEAD(&waiter->list);
}
+/* Dropping below function brings back hangs/lockups & reboots */
+#if 0
void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
{
lockdep_assert_held(&lock->wait_lock);
@@ -41,6 +43,7 @@ void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
}
+#endif
void debug_mutex_free_waiter(struct mutex_waiter *waiter)
{
View attachment "mutex-fix-bcm53573.diff" of type "text/x-patch" (2238 bytes)
Powered by blists - more mailing lists