linux-kernel - Re: [PATCH] mm: add gfp_mask parameter to vm_map

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Message-ID: <4FD94EE8.9030300@kernel.org>
Date:	Thu, 14 Jun 2012 11:39:36 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Tejun Heo <tj@...nel.org>
CC:	Fengguang Wu <fengguang.wu@...el.com>,
	Dave Chinner <dchinner@...hat.com>,
	Christoph Hellwig <hch@...radead.org>,
	linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Memory Management List <linux-mm@...ck.org>,
	xfs@....sgi.com
Subject: Re: [PATCH] mm: add gfp_mask parameter to vm_map_ram()

On 06/14/2012 11:21 AM, Tejun Heo wrote:

> Hello, guys.
> 
> On Thu, Jun 14, 2012 at 11:07:53AM +0900, Minchan Kim wrote:
>> It shouldn't work because vmap_page_range still can allocate
>> GFP_KERNEL by pud_alloc in vmap_pud_range.  For it, I tried [1] but
>> other mm guys want to add WARNING [2] so let's avoiding gfp context
>> passing.
>>
>> [1] https://lkml.org/lkml/2012/4/23/77
>> [2] https://lkml.org/lkml/2012/5/2/340
> 
> Yeah, vmalloc area doesn't support !GFP_KERNEL allocations and as
> Minchan said, changing this would require updating page table
> allocation functions on all archs.  This is the same reason why percpu
> allocator doesn't support !GFP_KERNEL allocations which in turn made
> blk-throttle implement its own private percpu pool.
> 
> If xfs can't live without GFP_NOFS vmalloc allocations, either it has
> to implement its own pool or maybe it's time to implement !GFP_KERNEL
> allocs for vmalloc area.  I don't know.


There is another example in ARM. 
http://www.spinics.net/lists/arm-kernel/msg179202.html
They try to make pool for atomic vmalloc support. :(
Only GFP_KERNEL support vmalloc spreads out many pools in system, Sigh. 

-- 
Kind regards,
Minchan Kim
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