2017-08-10 20:07:42

by Seraphime Kirkovski

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Subject: KASAN + general protection fault while writing to mmc

Hi,

I got this while restoring a backup with dd on an SDCard.
On 4.13.0-rc4 I get it everytime.

I'm not sure if it isn't a hardware problem as I have no more cards
left.



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2017-08-22 12:17:42

by Linus Walleij

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Subject: Re: KASAN + general protection fault while writing to mmc

On Thu, Aug 10, 2017 at 10:07 PM, Seraphime Kirkovski
<[email protected]> wrote:

> I got this while restoring a backup with dd on an SDCard.
> On 4.13.0-rc4 I get it everytime.
>
> I'm not sure if it isn't a hardware problem as I have no more cards
> left.

The only patch that touched blk_rq_map_sg() that calls sg_next()
was this:

commit 67e69d5220c904238f94bb2e6001d7c590f5a0bb
Author: Linus Walleij <[email protected]>
Date: Fri May 19 15:37:27 2017 +0200

mmc: block: remove req back pointer

Just as we can use blk_mq_rq_from_pdu() to get the per-request
tag we can use blk_mq_rq_to_pdu() to get a request from a tag.
Introduce a static inline helper so we are on the clear what
is happening.

Suggested-by: Christoph Hellwig <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>
Signed-off-by: Ulf Hansson <[email protected]>

Can you try reverting it and see if the problem goes away?

Yours,
Linus Walleij

2017-08-22 15:52:37

by Seraphime Kirkovski

[permalink] [raw]
Subject: Re: KASAN + general protection fault while writing to mmc

On Tue, Aug 22, 2017 at 02:17:38PM +0200, Linus Walleij wrote:

> commit 67e69d5220c904238f94bb2e6001d7c590f5a0bb
> Author: Linus Walleij <[email protected]>
> Date: Fri May 19 15:37:27 2017 +0200
>
> mmc: block: remove req back pointer
>
> Just as we can use blk_mq_rq_from_pdu() to get the per-request
> tag we can use blk_mq_rq_to_pdu() to get a request from a tag.
> Introduce a static inline helper so we are on the clear what
> is happening.
>
> Suggested-by: Christoph Hellwig <[email protected]>
> Signed-off-by: Linus Walleij <[email protected]>
> Signed-off-by: Ulf Hansson <[email protected]>
>
> Can you try reverting it and see if the problem goes away?
>
> Yours,
> Linus Walleij

Thanks for the reply !

The problem doesn't go away, it is only delayed.

Will try to find some time to bisect it.

Thanks,
Seraphime Kirkovski