Re: [PATCH] iommu/io-pgtable-arm-v7s: Add error handle for page table allocation failure

From: Will Deacon <will@kernel.org>
To: yf.wang@mediatek.com
Cc: Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	"moderated list:ARM SMMU DRIVERS"
	<linux-arm-kernel@lists.infradead.org>,
	"open list:IOMMU DRIVERS" <iommu@lists.linux-foundation.org>,
	open list <linux-kernel@vger.kernel.org>,
	"moderated list:ARM/Mediatek SoC support"
	<linux-mediatek@lists.infradead.org>,
	wsd_upstream@mediatek.com, Libo Kang <Libo.Kang@mediatek.com>,
	Yong Wu <Yong.Wu@mediatek.com>,
	Guangming Cao <Guangming.Cao@mediatek.com>
Subject: Re: [PATCH] iommu/io-pgtable-arm-v7s: Add error handle for page table allocation failure
Date: Tue, 7 Dec 2021 09:48:18 +0000	[thread overview]
Message-ID: <20211207094817.GA31382@willie-the-truck> (raw)
In-Reply-To: <20211207024723.25751-1-yf.wang@mediatek.com>

On Tue, Dec 07, 2021 at 10:47:22AM +0800, yf.wang@mediatek.com wrote:
> From: Yunfei Wang <yf.wang@mediatek.com>
> 
> In __arm_v7s_alloc_table function:
> iommu call kmem_cache_alloc to allocate page table, this function
> allocate memory may fail, when kmem_cache_alloc fails to allocate
> table, call virt_to_phys will be abnomal and return unexpected phys
> and goto out_free, then call kmem_cache_free to release table will
> trigger KE, __get_free_pages and free_pages have similar problem,
> so add error handle for page table allocation failure.
> 
> Signed-off-by: Yunfei Wang <yf.wang@mediatek.com>
> ---
>  drivers/iommu/io-pgtable-arm-v7s.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
> index bfb6acb651e5..d84240308f4b 100644
> --- a/drivers/iommu/io-pgtable-arm-v7s.c
> +++ b/drivers/iommu/io-pgtable-arm-v7s.c
> @@ -246,6 +246,12 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
>  			__GFP_ZERO | ARM_V7S_TABLE_GFP_DMA, get_order(size));
>  	else if (lvl == 2)
>  		table = kmem_cache_zalloc(data->l2_tables, gfp);
> +
> +	if (!table) {
> +		dev_err(dev, "Page table allocation failure lvl:%d\n", lvl);

I'd expect the allocator to shout loudly on failure anyway, so I don't think
we need to print another message here.

Will

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