linux-kernel - Re: [PATCH] Mark thread stack correctly in proc/<pid>/maps

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Message-ID: <CAAHN_R1u_btMuF+WhHu0G895EJ=mbOPNRp7NcXEgTKv3Vs-B1A@mail.gmail.com>
Date:	Mon, 16 Jan 2012 18:38:33 +0530
From:	Siddhesh Poyarekar <siddhesh.poyarekar@...il.com>
To:	Jamie Lokier <jamie@...reable.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org,
	Michael Kerrisk <mtk.manpages@...il.com>,
	linux-man@...r.kernel.org
Subject: Re: [PATCH] Mark thread stack correctly in proc/<pid>/maps

On Mon, Jan 16, 2012 at 4:58 PM, Jamie Lokier <jamie@...reable.org> wrote:
> Is there a reason the names aren't consistent - i.e. not vma_is_stack_guard()?

Ah, that was an error on my part; I did not notice the naming convention.

> How about simply calling it vma_is_guard(), return 1 if it's PROT_NONE
> without checking vma_is_stack() or ->vm_next/prev, and annotate the
> maps output like this:
>
>   is_stack              => "[stack]"
>   is_guard & is_stack   => "[stack guard]"
>   is_guard & !is_stack  => "[guard]"
>
> What do you think?

Thanks for the review. We're already marking permissions in the maps
output to convey protection, so isn't marking those vmas as [guard]
redundant?

Following that, we could just mark the thread stack guard as [stack]
without any permissions. The process stack guard page probably
deserves the [stack guard] label since it is marked differently from
the thread stack guard and will otherwise have the permissions that
the process stack has. Will that be good?

-- 
Siddhesh Poyarekar
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