From: Johannes Weiner <hannes@cmpxchg.org>
To: Uma shankar <shankar.vk@gmail.com>
Cc: linux-mm@kvack.org
Subject: Re: accessing stack of non-current task
Date: Tue, 20 Apr 2010 15:43:22 +0200 [thread overview]
Message-ID: <20100420134322.GM20640@cmpxchg.org> (raw)
In-Reply-To: <y2t448a67a1004200538l45d46338vcd77b63a0e53d54e@mail.gmail.com>
On Tue, Apr 20, 2010 at 06:08:14PM +0530, Uma shankar wrote:
> Hi,
>
> Is it possible for the kernel to access the user-stack data of a
> task different from "current" ? ( This is needed for stack-dump as
> well as backtrace. )
Yes, have a look at __get_user_pages() in mm/memory.c.
> I thought the answer is "no". ( Kernel sees memory through the
> page-table of "current" )
That is correct when using virtual addresses and letting the MMU
do the page table lookup in the currently active page tables.
But if you have the task_struct of another process, you can easily
get to its vmas and page tables (task->mm) and walk them in software.
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next prev parent reply other threads:[~2010-04-20 13:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-20 12:38 Uma shankar
2010-04-20 13:43 ` Johannes Weiner [this message]
2010-04-20 14:00 ` Uma shankar
2010-04-20 17:16 ` Johannes Weiner
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