From: Crestez Dan Leonard <cdleonard@gmail.com>
To: Jonathan Toppins <jtoppins@cumulusnetworks.com>
Cc: netdev@vger.kernel.org
Subject: Re: [RFC] tcp md5 use of alloc_percpu
Date: Thu, 23 Oct 2014 04:00:39 +0300 [thread overview]
Message-ID: <54485337.5040108@gmail.com> (raw)
In-Reply-To: <54483FF7.4090208@cumulusnetworks.com>
On 10/23/2014 02:38 AM, Jonathan Toppins wrote:
> On 10/22/14, 2:55 PM, Crestez Dan Leonard wrote:
>> sg_init_one does virt_addr on the pointer which assumes it is directly accessible. But the tcp_md5sig_pool pointer comes from alloc_percpu which can return memory from the vmalloc area after the pcpu_first_chunk is exhausted. This looks wrong to me. I'm am getting crashes on mips and I believe this to be the cause.
>
> Thinking about this more if the issue really is sg_init_one assumes a
> directly accessible memory region, can we just modify the zone
> allocation to GFP_DMA using alloc_percpu_gfp()? Does this satisfy the
> assumptions made by sg_init_one?
I don't think that alloc_percpu_gfp can be used that way. Looking at the
code it only checks for GFP_KERNEL and behaves "atomically" if it is not
present. This means that it fails rather than vmalloc a new percpu_chunk.
The problem is not that the memory is not allocated with GFP_DMA but
rather that the memory is allocated with vmalloc.
Regards,
Leonard
next prev parent reply other threads:[~2014-10-23 1:00 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-22 18:55 [RFC] tcp md5 use of alloc_percpu Crestez Dan Leonard
2014-10-22 19:12 ` Eric Dumazet
2014-10-22 21:35 ` Jonathan Toppins
2014-10-22 23:05 ` Crestez Dan Leonard
2014-10-24 9:33 ` Herbert Xu
2014-10-22 21:53 ` David Miller
2014-10-22 23:38 ` Jonathan Toppins
2014-10-23 1:00 ` Crestez Dan Leonard [this message]
2014-10-23 1:47 ` Eric Dumazet
2014-10-23 4:40 ` David Ahern
2014-10-23 5:23 ` Eric Dumazet
2014-10-23 5:38 ` Eric Dumazet
2014-10-23 6:58 ` Jonathan Toppins
2014-10-23 13:21 ` Eric Dumazet
2014-10-23 14:43 ` Eric Dumazet
2014-10-23 16:17 ` Crestez Dan Leonard
2014-10-23 19:22 ` Eric Dumazet
2014-10-23 16:33 ` [PATCH net] tcp: md5: percpu tcp_md5sig_pool must not span pages Eric Dumazet
2014-10-23 19:34 ` Eric Dumazet
2014-10-23 19:58 ` [PATCH v2 net] tcp: md5: do not use alloc_percpu() Eric Dumazet
2014-10-23 20:44 ` David Ahern
2014-10-23 22:57 ` Eric Dumazet
2014-10-23 23:36 ` David Ahern
2014-10-24 3:45 ` David Ahern
2014-10-25 20:11 ` David Miller
2014-10-23 14:46 ` [RFC] tcp md5 use of alloc_percpu Crestez Dan Leonard
2014-10-23 13:03 ` Crestez Dan Leonard
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