From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: catalin.marinas@arm.com, will.deacon@arm.com,
keescook@chromium.org, arnd@arndb.de,
linux-arm-kernel@lists.infradead.org,
Anders Roxell <anders.roxell@linaro.org>,
Ingo Molnar <mingo@kernel.org>
Subject: [PATCH 2/2] arm64: ftrace: Set FTRACE_SCHEDULABLE before ftrace_modify_all_code()
Date: Wed, 05 Dec 2018 12:48:54 -0500 [thread overview]
Message-ID: <20181205183304.000714627@goodmis.org> (raw)
In-Reply-To: 20181205174852.435233070@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
It has been reported that ftrace_replace_code() which is called by
ftrace_modify_all_code() can cause a soft lockup warning for an
allmodconfig kernel. This is because all the debug options enabled
causes the loop in ftrace_replace_code() (which loops over all the
functions being enabled where there can be 10s of thousands), is too
slow, and never schedules out.
To solve this, setting FTRACE_SCHEDULABLE to the command passed into
ftrace_replace_code() will make it call cond_resched() in the loop,
which prevents the soft lockup warning from triggering.
Link: http://lkml.kernel.org/r/20181204192903.8193-1-anders.roxell@linaro.org
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
arch/arm64/kernel/ftrace.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 57e962290df3..9a8de0a79f97 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -193,6 +193,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
void arch_ftrace_update_code(int command)
{
+ command |= FTRACE_SCHEDULABLE;
ftrace_modify_all_code(command);
}
--
2.19.1
next prev parent reply other threads:[~2018-12-05 18:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 17:48 [PATCH 0/2] tracing: arm64: Make ftrace_replace_code() schedulable for arm64 Steven Rostedt
2018-12-05 17:48 ` [PATCH 1/2] ftrace: Allow ftrace_replace_code() to be schedulable Steven Rostedt
2018-12-06 14:32 ` Anders Roxell
2018-12-05 17:48 ` Steven Rostedt [this message]
2018-12-06 13:20 ` [PATCH 2/2] arm64: ftrace: Set FTRACE_SCHEDULABLE before ftrace_modify_all_code() Will Deacon
2018-12-06 14:31 ` Anders Roxell
2018-12-06 15:59 ` Steven Rostedt
2018-12-06 16:06 ` Will Deacon
2018-12-05 18:47 ` [PATCH 0/2] tracing: arm64: Make ftrace_replace_code() schedulable for arm64 Anders Roxell
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