From: Guenter Roeck <linux@roeck-us.net>
To: Eric Dumazet <edumazet@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>
Subject: Re: Linux 5.12-rc7
Date: Mon, 12 Apr 2021 10:31:17 -0700 [thread overview]
Message-ID: <78c858ba-a847-884f-80c3-cb1eb84d4113@roeck-us.net> (raw)
In-Reply-To: <CANn89iK2aUESa6DSG=Y4Y9tPmPW2weE05AVpxnDbqYwQjFM2Vw@mail.gmail.com>
On 4/12/21 9:31 AM, Eric Dumazet wrote:
> On Mon, Apr 12, 2021 at 6:28 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> On Sun, Apr 11, 2021 at 10:14 PM Guenter Roeck <linux@roeck-us.net> wrote:
>>>
>>> Qemu test results:
>>> total: 460 pass: 459 fail: 1
>>> Failed tests:
>>> sh:rts7751r2dplus_defconfig:ata:net,virtio-net:rootfs
>>>
>>> The failure bisects to commit 0f6925b3e8da ("virtio_net: Do not pull payload in
>>> skb->head"). It is a spurious problem - the test passes roughly every other
>>> time. When the failure is seen, udhcpc fails to get an IP address and aborts
>>> with SIGTERM. So far I have only seen this with the "sh" architecture.
>>
>> Hmm. Let's add in some more of the people involved in that commit, and
>> also netdev.
>>
>> Nothing in there looks like it should have any interaction with
>> architecture, so that "it happens on sh" sounds odd, but maybe it's
>> some particular interaction with the qemu environment.
>
> Yes, maybe.
>
> I spent few hours on this, and suspect a buggy memcpy() implementation
> on SH, but this was not conclusive.
>
I replaced all memcpy() calls in skbuff.h with calls to
static inline void __my_memcpy(unsigned char *to, const unsigned char *from,
unsigned int len)
{
while (len--)
*to++ = *from++;
}
That made no difference, so unless you have some other memcpy() in mind that
seems to be unlikely.
> By pulling one extra byte, the problem goes away.
>
> Strange thing is that the udhcpc process does not go past sendto().
>
I have been trying to debug that one. Unfortunately gdb doesn't work with sh,
so I can't use it to debug the problem. I'll spend some more time on this today.
Thanks,
Guenter
next prev parent reply other threads:[~2021-04-12 17:31 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-11 22:41 Linux 5.12-rc7 Linus Torvalds
2021-04-12 5:14 ` Guenter Roeck
2021-04-12 16:28 ` Linus Torvalds
2021-04-12 16:31 ` Michael S. Tsirkin
2021-04-12 16:31 ` Eric Dumazet
2021-04-12 16:47 ` Eric Dumazet
2021-04-13 12:57 ` Michael S. Tsirkin
2021-04-13 13:27 ` Eric Dumazet
2021-04-13 13:33 ` Eric Dumazet
2021-04-13 13:37 ` Michael S. Tsirkin
2021-04-13 13:42 ` Eric Dumazet
2021-04-13 13:46 ` Michael S. Tsirkin
2021-04-13 13:58 ` Michael S. Tsirkin
2021-04-12 17:31 ` Guenter Roeck [this message]
2021-04-12 17:38 ` Eric Dumazet
2021-04-12 20:05 ` Guenter Roeck
2021-04-13 9:24 ` Eric Dumazet
2021-04-13 10:43 ` Eric Dumazet
2021-04-13 12:45 ` Eric Dumazet
2021-04-13 12:52 ` Michael S. Tsirkin
2021-04-12 2:03 Ronald Warsow
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