linux-kernel - Re: Regression after commit 19809c2da28a ("mm, vmalloc: use __GFP

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Message-ID: <d7314317-f3d6-a38d-326a-7a27e05a5e67@redhat.com>
Date:   Thu, 8 Feb 2018 10:34:42 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Kai Heng Feng <kai.heng.feng@...onical.com>,
        Michal Hocko <mhocko@...e.com>, linux-mm@...ck.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Regression after commit 19809c2da28a ("mm, vmalloc: use
 __GFP_HIGHMEM implicitly")

On 02/08/2018 10:18 AM, Matthew Wilcox wrote:
> On Thu, Feb 08, 2018 at 09:56:42AM -0800, Laura Abbott wrote:
>>> +++ b/drivers/media/v4l2-core/videobuf-dma-sg.c
>>> @@ -77,7 +77,7 @@ static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
>>>    		pg = vmalloc_to_page(virt);
>>>    		if (NULL == pg)
>>>    			goto err;
>>> -		BUG_ON(PageHighMem(pg));
>>> +		BUG_ON(page_to_pfn(pg) >= (1 << (32 - PAGE_SHIFT)));
>>>    		sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
>>>    	}
>>>    	return sglist;
>>>
>>
>> the vzalloc in this function needs to be switched to vmalloc32 if it
>> actually wants to guarantee 32-bit memory.
> 
> Whoops, you got confused between the sglist allocation and the allocation
> of the pages which will be mapped ...
> 

Ah yeah, clearly need more coffee this morning.