From: Catalin Marinas <catalin.marinas@arm.com>
To: Christoph Lameter <cl@linux.com>
Cc: mark.rutland@arm.com, Jungseok Lee <jungseoklee85@gmail.com>,
linux-mm@kvack.org, barami97@gmail.com, will.deacon@arm.com,
linux-kernel@vger.kernel.org, takahiro.akashi@linaro.org,
james.morse@arm.com, tj@kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v6 2/3] percpu: add PERCPU_ATOM_SIZE for a generic percpu area setup
Date: Mon, 2 Nov 2015 17:35:20 +0000 [thread overview]
Message-ID: <20151102173520.GC7637@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1511021047420.28255@east.gentwo.org>
On Mon, Nov 02, 2015 at 10:48:17AM -0600, Christoph Lameter wrote:
> On Mon, 2 Nov 2015, Catalin Marinas wrote:
> > I haven't looked at the patch 3/3 in detail but I'm pretty sure I'll NAK
> > the approach (and the definition of PERCPU_ATOM_SIZE), therefore
> > rendering this patch unnecessary. IIUC, this is used to enforce some
> > alignment of the per-CPU IRQ stack to be able to check whether the
> > current stack is process or IRQ on exception entry. But there are other,
> > less intrusive ways to achieve the same (e.g. x86).
>
> The percpu allocator allows the specification of alignment requirements.
Patch 3/3 does something like this:
DEFINE_PER_CPU(char [IRQ_STACK_SIZE], irq_stacks) __aligned(IRQ_STACK_SIZE)
where IRQ_STACK_SIZE > PAGE_SIZE. AFAICT, setup_per_cpu_areas() doesn't
guarantee alignment greater than PAGE_SIZE.
--
Catalin
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2015-11-02 17:35 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-01 7:46 [PATCH v6 0/3] Introduce IRQ stack on arm64 with percpu changes Jungseok Lee
2015-11-01 7:46 ` [PATCH v6 1/3] percpu: remove PERCPU_ENOUGH_ROOM which is stale definition Jungseok Lee
2015-11-02 16:08 ` Christoph Lameter
2015-11-02 19:10 ` Tejun Heo
2015-11-03 14:12 ` Jungseok Lee
2015-11-03 22:07 ` Tejun Heo
2015-11-04 13:19 ` Jungseok Lee
2015-11-01 7:46 ` [PATCH v6 2/3] percpu: add PERCPU_ATOM_SIZE for a generic percpu area setup Jungseok Lee
2015-11-02 16:10 ` Christoph Lameter
2015-11-02 16:22 ` Catalin Marinas
2015-11-02 16:48 ` Christoph Lameter
2015-11-02 17:35 ` Catalin Marinas [this message]
2015-11-02 18:11 ` Christoph Lameter
2015-11-02 18:31 ` Catalin Marinas
2015-11-03 13:49 ` Jungseok Lee
2015-11-03 17:58 ` James Morse
2015-11-04 13:35 ` Jungseok Lee
2015-11-03 14:11 ` Jungseok Lee
2015-11-01 7:46 ` [PATCH v6 3/3] arm64: Introduce IRQ stack Jungseok Lee
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=20151102173520.GC7637@e104818-lin.cambridge.arm.com \
--to=catalin.marinas@arm.com \
--cc=barami97@gmail.com \
--cc=cl@linux.com \
--cc=james.morse@arm.com \
--cc=jungseoklee85@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mark.rutland@arm.com \
--cc=takahiro.akashi@linaro.org \
--cc=tj@kernel.org \
--cc=will.deacon@arm.com \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox