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:

quoted

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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