From: Arnd Bergmann <arnd@arndb.de>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Michel Lespinasse <walken@google.com>,
Byungchul Park <byungchul.park@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
willy@infradead.org, Nicholas Piggin <npiggin@gmail.com>,
kernel-team@lge.com
Subject: Re: [PATCH 0/2] completion: Reduce stack usage caused by COMPLETION_INITIALIZER_ONSTACK()
Date: Wed, 23 Aug 2017 17:33:00 +0200 [thread overview]
Message-ID: <CAK8P3a1FN8FoRNn8GYiPNTzAxGg_x+qkw5Z7eARTBirUkug2gQ@mail.gmail.com> (raw)
In-Reply-To: <20170823152542.5150-1-boqun.feng@gmail.com>
On Wed, Aug 23, 2017 at 5:25 PM, Boqun Feng <boqun.feng@gmail.com> wrote:
> With LOCKDEP_CROSSRELEASE and LOCKDEP_COMPLETIONS introduced, the growth
> in kernel stack usage of several functions were reported:
>
> https://marc.info/?l=linux-kernel&m=150270063231284&w=2
>
> The root cause of this is in COMPLETION_INITIALIZER_ONSTACK(), we use
>
> ({init_completion(&work); work})
>
> , which will create a temporary object when returned. However this
> temporary object is unnecessary. And this patch fixes it by making the
> statement expression in COMPLETION_INITIALIZER_ONSTACK() return a
> pointer rather than a whole structure. This will reduce the stack usage
> even if !LOCKDEP.
>
> However, such a change does make one COMPLETION_INITIALIZER_ONSTACK()
> callsite invalid, so we fix this first via converting to
> init_completion().
Both patches
Acked-by: Arnd Bergmann <arnd@arndb.de>
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prev parent reply other threads:[~2017-08-23 15:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-23 15:25 [PATCH 0/2] completion: Reduce stack usage caused by COMPLETION_INITIALIZER_ONSTACK() Boqun Feng
2017-08-23 15:25 ` [PATCH 1/2] nfit: Use init_completion() in acpi_nfit_flush_probe() Boqun Feng
2017-08-23 22:08 ` Dan Williams
2017-08-24 13:07 ` Thomas Gleixner
2017-08-24 13:28 ` Boqun Feng
2017-08-24 13:46 ` Arnd Bergmann
2017-08-24 14:22 ` [PATCH v2 1/2] nfit: Fix the abuse of COMPLETION_INITIALIZER_ONSTACK() Boqun Feng
2017-08-25 0:18 ` Boqun Feng
2017-08-25 0:36 ` Dan Williams
2017-08-23 15:25 ` [PATCH 2/2] completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK() Boqun Feng
2017-08-23 15:33 ` Arnd Bergmann [this message]
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