From: Will Deacon <will.deacon@arm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Anders Roxell <anders.roxell@linaro.org>,
keescook@chromium.org, arnd@arndb.de, catalin.marinas@arm.com,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/2] arm64: ftrace: Set FTRACE_SCHEDULABLE before ftrace_modify_all_code()
Date: Thu, 6 Dec 2018 13:20:07 +0000 [thread overview]
Message-ID: <20181206132007.GB27744@arm.com> (raw)
In-Reply-To: <20181205183304.000714627@goodmis.org>
On Wed, Dec 05, 2018 at 12:48:54PM -0500, Steven Rostedt wrote:
> 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);
> }
Bikeshed: I'd probably go for FTRACE_MAY_SLEEP, but I'm not going to die
on that hill so...
Acked-by: Will Deacon <will.deacon@arm.com>
Thanks, Steve!
Will
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, catalin.marinas@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: Re: [PATCH 2/2] arm64: ftrace: Set FTRACE_SCHEDULABLE before ftrace_modify_all_code()
Date: Thu, 6 Dec 2018 13:20:07 +0000 [thread overview]
Message-ID: <20181206132007.GB27744@arm.com> (raw)
In-Reply-To: <20181205183304.000714627@goodmis.org>
On Wed, Dec 05, 2018 at 12:48:54PM -0500, Steven Rostedt wrote:
> 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);
> }
Bikeshed: I'd probably go for FTRACE_MAY_SLEEP, but I'm not going to die
on that hill so...
Acked-by: Will Deacon <will.deacon@arm.com>
Thanks, Steve!
Will
next prev parent reply other threads:[~2018-12-06 13:20 UTC|newest]
Thread overview: 18+ 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 ` Steven Rostedt
2018-12-05 17:48 ` [PATCH 1/2] ftrace: Allow ftrace_replace_code() to be schedulable Steven Rostedt
2018-12-05 17:48 ` Steven Rostedt
2018-12-06 14:32 ` Anders Roxell
2018-12-06 14:32 ` Anders Roxell
2018-12-05 17:48 ` [PATCH 2/2] arm64: ftrace: Set FTRACE_SCHEDULABLE before ftrace_modify_all_code() Steven Rostedt
2018-12-05 17:48 ` Steven Rostedt
2018-12-06 13:20 ` Will Deacon [this message]
2018-12-06 13:20 ` Will Deacon
2018-12-06 14:31 ` Anders Roxell
2018-12-06 14:31 ` Anders Roxell
2018-12-06 15:59 ` Steven Rostedt
2018-12-06 15:59 ` Steven Rostedt
2018-12-06 16:06 ` Will Deacon
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
2018-12-05 18:47 ` Anders Roxell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181206132007.GB27744@arm.com \
--to=will.deacon@arm.com \
--cc=anders.roxell@linaro.org \
--cc=arnd@arndb.de \
--cc=catalin.marinas@arm.com \
--cc=keescook@chromium.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.