[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Thu, 02 Feb 2012 21:31:03 +0800
From: Cong Wang <xiyou.wangcong@...il.com>
To: Arnd Bergmann <arnd@...db.de>
CC: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, Prarit Bhargava <prarit@...hat.com>,
Greg Kroah-Hartman <greg@...ah.com>
Subject: Re: [Patch] lkdtm: avoid calling lkdtm_do_action() with spin lock
held
On 02/01/2012 11:29 PM, Arnd Bergmann wrote:
> On Wednesday 01 February 2012, Cong Wang wrote:
>> On 01/31/2012 11:35 PM, Arnd Bergmann wrote:
>>> On Tuesday 31 January 2012, Cong Wang wrote:
>>>> @@ -323,14 +323,16 @@ static void lkdtm_do_action(enum ctype which)
>>>> }
>>>> case CT_WRITE_AFTER_FREE: {
>>>> size_t len = 1024;
>>>> - u32 *data = kmalloc(len, GFP_KERNEL);
>>>> + u32 *data = kmalloc(len, GFP_ATOMIC);
>>>>
>>>> kfree(data);
>>>> - schedule();
>>>> + udelay(100);
>>>> memset(data, 0x78, len);
>>>> break;
>>>> }
>>>
>>> I can't think of why the udelay would have any positive effect here,
>>> if the idea of the schedule was to let some other process allocate and
>>> use the memory.
>>
>>
>> Hmm, on SMP udelay on this CPU will give a chance to other CPU's to use
>> that memory, right?
>>
>
> There is a small chance for that, but it's much less likely than it would
> be using another process on the same CPU, plus it requires SMP.
Yeah, I updated this in [PATCH 2/2] lkdtm: avoid calling sleeping
functions in interrupt context.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists