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

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Message-Id: <2DB8D5E5-0955-47CF-A142-09A5BA71DF70@canonical.com>
Date:   Fri, 9 Feb 2018 17:12:56 +0800
From:   Kai Heng Feng <kai.heng.feng@...onical.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Michal Hocko <mhocko@...e.com>, Laura Abbott <labbott@...hat.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")

Hi Matthew,

> On Feb 9, 2018, at 12:08 PM, Matthew Wilcox <willy@...radead.org> wrote:
> Alternatively, try this.  It passes in GFP_DMA32 from vmalloc_32,
> regardless of whether ZONE_DMA32 exists or not.  If ZONE_DMA32 doesn't
> exist, then we clear it in __vmalloc_area_node(), after using it to
> determine that we shouldn't set __GFP_HIGHMEM.

IIUC, I need to let drivers/media drivers start using vmalloc_32() with  
your patch, right?

Kai-Heng

>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 673942094328..91e8a95123c4 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1669,10 +1669,11 @@ static void *__vmalloc_area_node(struct vm_struct  
> *area, gfp_t gfp_mask,
>  	struct page **pages;
>  	unsigned int nr_pages, array_size, i;
>  	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
> -	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
> -	const gfp_t highmem_mask = (gfp_mask & (GFP_DMA | GFP_DMA32)) ?
> -					0 :
> -					__GFP_HIGHMEM;
> +	gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
> +	if (!(alloc_mask & GFP_ZONEMASK))
> +		alloc_mask |= __GFP_HIGHMEM;
> +	if (!IS_ENABLED(CONFIG_ZONE_DMA32) && (alloc_mask & __GFP_DMA32))
> +		alloc_mask &= ~__GFP_DMA32;
>
>  	nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
>  	array_size = (nr_pages * sizeof(struct page *));
> @@ -1680,7 +1681,7 @@ static void *__vmalloc_area_node(struct vm_struct  
> *area, gfp_t gfp_mask,
>  	area->nr_pages = nr_pages;
>  	/* Please note that the recursion is strictly bounded. */
>  	if (array_size > PAGE_SIZE) {
> -		pages = __vmalloc_node(array_size, 1, nested_gfp|highmem_mask,
> +		pages = __vmalloc_node(array_size, 1, nested_gfp|__GFP_HIGHMEM,
>  				PAGE_KERNEL, node, area->caller);
>  	} else {
>  		pages = kmalloc_node(array_size, nested_gfp, node);
> @@ -1696,9 +1697,9 @@ static void *__vmalloc_area_node(struct vm_struct  
> *area, gfp_t gfp_mask,
>  		struct page *page;
>
>  		if (node == NUMA_NO_NODE)
> -			page = alloc_page(alloc_mask|highmem_mask);
> +			page = alloc_page(alloc_mask);
>  		else
> -			page = alloc_pages_node(node, alloc_mask|highmem_mask, 0);
> +			page = alloc_pages_node(node, alloc_mask, 0);
>
>  		if (unlikely(!page)) {
>  			/* Successfully allocated i pages, free them in __vunmap() */
> @@ -1706,7 +1707,7 @@ static void *__vmalloc_area_node(struct vm_struct  
> *area, gfp_t gfp_mask,
>  			goto fail;
>  		}
>  		area->pages[i] = page;
> -		if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
> +		if (gfpflags_allow_blocking(gfp_mask))
>  			cond_resched();
>  	}
>
> @@ -1942,12 +1943,10 @@ void *vmalloc_exec(unsigned long size)
>  			      NUMA_NO_NODE, __builtin_return_address(0));
>  }
>
> -#if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
> -#define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
> -#elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
> +#if defined(CONFIG_64BIT) && !defined(CONFIG_ZONE_DMA32)
>  #define GFP_VMALLOC32 GFP_DMA | GFP_KERNEL
>  #else
> -#define GFP_VMALLOC32 GFP_KERNEL
> +#define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
>  #endif
>
>  /**