linux-kernel - Re: [PATCH v4 3/6] iommu: add ARM short descriptor page table allocator.

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Date:	Fri, 9 Oct 2015 18:41:51 +0100
From:	Robin Murphy <robin.murphy@....com>
To:	Will Deacon <will.deacon@....com>, Yong Wu <yong.wu@...iatek.com>
Cc:	Mark Rutland <Mark.Rutland@....com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"youhua.li@...iatek.com" <youhua.li@...iatek.com>,
	Thierry Reding <treding@...dia.com>,
	"k.zhang@...iatek.com" <k.zhang@...iatek.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"arnd@...db.de" <arnd@...db.de>, Tomasz Figa <tfiga@...gle.com>,
	Rob Herring <robh+dt@...nel.org>,
	"linux-mediatek@...ts.infradead.org" 
	<linux-mediatek@...ts.infradead.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"pebolle@...cali.nl" <pebolle@...cali.nl>,
	"frederic.chen@...iatek.com" <frederic.chen@...iatek.com>,
	"srv_heupstream@...iatek.com" <srv_heupstream@...iatek.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	Daniel Kurtz <djkurtz@...gle.com>,
	Sasha Hauer <kernel@...gutronix.de>,
	Lucas Stach <l.stach@...gutronix.de>
Subject: Re: [PATCH v4 3/6] iommu: add ARM short descriptor page table
 allocator.

On 09/10/15 16:57, Will Deacon wrote:
> On Tue, Sep 22, 2015 at 03:12:47PM +0100, Yong Wu wrote:
>>       I would like to show you a problem I met, The recursion here may
>> lead to stack overflow while we test FHD video decode.
>>
>>      From the log, I get the internal variable in the error case: the
>> "size" is 0x100000, the "iova" is 0xfea00000, but at that time the
>> "blk_size" is 0x1000 as it was the map of small-page. so it enter the
>> recursion here.
>>
>>      After check the unmap flow, there is only a iommu_unmap in
>> __iommu_dma_unmap, and it won't check the physical address align in
>> iommu_unmap.
>
> That sounds like a bug in __iommu_dma_unmap. Robin?

Isn't it just cf27ec930be9 again wearing different trousers? All I do is 
call iommu_unmap with the same total size that was mapped originally.

Robin.

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