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

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Date:   Tue, 7 Dec 2021 09:48:18 +0000
From:   Will Deacon <will@...nel.org>
To:     yf.wang@...iatek.com
Cc:     Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "moderated list:ARM SMMU DRIVERS" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:IOMMU DRIVERS" <iommu@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>, wsd_upstream@...iatek.com,
        Libo Kang <Libo.Kang@...iatek.com>,
        Yong Wu <Yong.Wu@...iatek.com>,
        Guangming Cao <Guangming.Cao@...iatek.com>
Subject: Re: [PATCH] iommu/io-pgtable-arm-v7s: Add error handle for page
 table allocation failure

On Tue, Dec 07, 2021 at 10:47:22AM +0800, yf.wang@...iatek.com wrote:
> From: Yunfei Wang <yf.wang@...iatek.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@...iatek.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