From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Miroslav Benes <mbenes@suse.cz>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] x86, stacktrace: avoid recording save_stack_trace wrappers
Date: Fri, 29 Sep 2017 10:57:33 -0500 [thread overview]
Message-ID: <20170929155733.y4csusut3bmucght@treble> (raw)
In-Reply-To: <20170929092335.2744-1-vbabka@suse.cz>
On Fri, Sep 29, 2017 at 11:23:35AM +0200, Vlastimil Babka wrote:
> The save_stack_trace() and save_stack_trace_tsk() wrappers of
> __save_stack_trace() add themselves to the call stack, and thus appear in the
> recorded stacktraces. This is redundant and wasteful when we have limited space
> to record the useful part of the backtrace with e.g. page_owner functionality.
>
> Fix this by making sure __save_stack_trace() is noinline (which matches the
> current gcc decision) and bumping the skip in the wrappers
> (save_stack_trace_tsk() only when called for the current task). This is similar
> to what was done for arm in 3683f44c42e9 ("ARM: stacktrace: avoid listing
> stacktrace functions in stacktrace") and is pending for arm64.
>
> Also make sure that __save_stack_trace_reliable() doesn't get this problem in
> the future by marking it __always_inline (which matches current gcc decision),
> per Josh Poimboeuf.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
--
Josh
next prev parent reply other threads:[~2017-09-29 15:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-07 7:57 [PATCH] x86, stacktrace: avoid recording save_stack_trace wrappers Vlastimil Babka
2017-09-07 13:07 ` Josh Poimboeuf
2017-09-29 9:23 ` [PATCH v2] " Vlastimil Babka
2017-09-29 15:57 ` Josh Poimboeuf [this message]
2017-09-29 20:15 ` [tip:x86/debug] x86/stacktrace: Avoid recording save_stack_trace() wrappers tip-bot for Vlastimil Babka
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