* Re: [PATCH v3 2/2] lib/scatterlist: use page iterator in the mapping iterator
2013-02-23 4:29 ` [PATCH v3 2/2] lib/scatterlist: use page iterator in the mapping iterator Stephen Warren
@ 2013-02-23 20:04 ` Imre Deak
2013-02-23 23:45 ` Stephen Warren
1 sibling, 0 replies; 3+ messages in thread
From: Imre Deak @ 2013-02-23 20:04 UTC (permalink / raw)
To: Stephen Warren
Cc: linux-kernel, Andrew Morton, Maxim Levitsky, Tejun Heo,
Daniel Vetter, linaro-mm-sig, linux-next@vger•kernel.org
On Fri, 2013-02-22 at 21:29 -0700, Stephen Warren wrote:
> On 02/13/2013 08:10 AM, Imre Deak wrote:
> > For better code reuse use the newly added page iterator to iterate
> > through the pages. The offset, length within the page is still
> > calculated by the mapping iterator as well as the actual mapping.
> > Idea from Tejun Heo <tj@kernel•org>.
>
> This patch appears in linux-next since next-20130220. It breaks mounting
> a root filesystem on an SD card on the Raspberry Pi ARM platform, with
> errors such as those shown below.
>
> next-20130222 with just this patch reverted works fine.
Thanks for tracking this down. I noticed now an obvious mistake I've
made, not limiting the mapping size to page size :/ I didn't hit it
since it only causes a problem when the user of miter modifies
miter->consumed and I think nothing does this on my machine. Since the
sdhci driver on Raspberry Pi does this the following might fix the
problem you saw. Could you give it a try? It applies on top of
v4 of the patch [1]:
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 2645acf..b83c144 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -493,6 +493,8 @@ bool sg_miter_next(struct sg_mapping_iter *miter)
miter->__offset = pgoffset ? 0 : sg->offset;
miter->__remaining = sg->offset + sg->length -
(pgoffset << PAGE_SHIFT) - miter->__offset;
+ miter->__remaining = min_t(unsigned long, miter->__remaining,
+ PAGE_SIZE - miter->__offset);
}
miter->page = miter->piter.page;
miter->consumed = miter->length = miter->__remaining;
--Imre
[1]
http://lists.linaro.org/pipermail/linaro-mm-sig/2013-February/003069.html
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3 2/2] lib/scatterlist: use page iterator in the mapping iterator
2013-02-23 4:29 ` [PATCH v3 2/2] lib/scatterlist: use page iterator in the mapping iterator Stephen Warren
2013-02-23 20:04 ` Imre Deak
@ 2013-02-23 23:45 ` Stephen Warren
1 sibling, 0 replies; 3+ messages in thread
From: Stephen Warren @ 2013-02-23 23:45 UTC (permalink / raw)
To: Imre Deak
Cc: linux-kernel, Andrew Morton, Maxim Levitsky, Tejun Heo,
Daniel Vetter, linaro-mm-sig, linux-next@vger•kernel.org
On Sat, 23 Feb 2013 22:04:06 +0200, Imre Deak wrote:
> On Fri, 2013-02-22 at 21:29 -0700, Stephen Warren wrote:
>> On 02/13/2013 08:10 AM, Imre Deak wrote:
>>> For better code reuse use the newly added page iterator to iterate
>>> through the pages. The offset, length within the page is still
>>> calculated by the mapping iterator as well as the actual mapping.
>>> Idea from Tejun Heo <tj@kernel•org>.
>>
>> This patch appears in linux-next since next-20130220. It breaks mounting
>> a root filesystem on an SD card on the Raspberry Pi ARM platform, with
>> errors such as those shown below.
>>
>> next-20130222 with just this patch reverted works fine.
>
> ...
> the following might fix the
> problem you saw. Could you give it a try? It applies on top of
> v4 of the patch [1]:
Yes, thanks very much. That incremental patch you gave solves the
problem perfectly.
^ permalink raw reply [flat|nested] 3+ messages in thread