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Date: Tue, 28 Oct 2014 20:56:22 +0300
From: Kirill Tkhai <tkhai@yandex.ru>
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To: Peter Zijlstra <peterz@infradead.org>, Kirill Tkhai <ktkhai@parallels.com>
CC: Oleg Nesterov <oleg@redhat.com>, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@redhat.com>,
        Vladimir Davydov <vdavydov@parallels.com>,
        Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH 2/3] introduce probe_slab_address()
References: <1413962231.19914.130.camel@tkhai> <20141027195339.GA11736@redhat.com> <20141027195425.GC11736@redhat.com> <1414475091.8574.6.camel@tkhai> <20141028150102.GP3219@twins.programming.kicks-ass.net>
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On 28.10.2014 18:01, Peter Zijlstra wrote:
> On Tue, Oct 28, 2014 at 08:44:51AM +0300, Kirill Tkhai wrote:
>> В Пн, 27/10/2014 в 20:54 +0100, Oleg Nesterov пишет:
> 
>>> +#define probe_slab_address(addr, retval)	\
>>> +	probe_kernel_address(addr, retval)
>>
>> probe_kernel_read() was arch-dependent on tree platforms:
>>
>> arch/blackfin/mm/maccess.c
>> arch/parisc/lib/memcpy.c
>> arch/um/kernel/maccess.c
>>
>> But now we skip these arch-dependent implementations. Is there no a problem?
>
> Nope, see the first patch, it makes probe_kernel_address use
> __probe_kernel_read().
> 

Yes, probe_kernel_read() is in [1/3], but it's not the same as
__probe_kernel_read() for blackfin, for example.

It's defined as

long __weak probe_kernel_read(void *dst, const void *src, size_t size)
    __attribute__((alias("__probe_kernel_read")));

But blackfin's probe_kernel_read() redefines this __weak function,
isn't it? Didn't get_freepointer_safe() use to call architecture's
probe_kernel_read() before?

I don't see how it is called now...