* Possible reasons of CMA allocation failure
@ 2018-02-04 22:58 Alexey Skidanov
2018-02-05 13:46 ` Alexey Skidanov
0 siblings, 1 reply; 2+ messages in thread
From: Alexey Skidanov @ 2018-02-04 22:58 UTC (permalink / raw)
To: linux-mm, labbott
Hello,
On x86 machine with 16GB RAM installed, I reserved 1 GB area for CMA:
[ 0.000000] cma: Reserved 1024 MiB at 0x00000003fcc00000
Some time after the boot, CMa failed to allocate chunk of memory while
there are enough contiguous pages:
[ 392.132392] cma: cma_alloc: alloc failed, req-size: 200000 pages,
ret: -16
[ 392.132393] cma: number of available pages:
6@8314+9@8343+9@8375+253648@8496=> 253672 free of 262144 total pages
[ 392.132398] cma: cma_alloc(): returned (null)
What are the possible reasons for such failure (besides the pinned user
allocated pages) ?
Thanks,
Alexey
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* Re: Possible reasons of CMA allocation failure
2018-02-04 22:58 Possible reasons of CMA allocation failure Alexey Skidanov
@ 2018-02-05 13:46 ` Alexey Skidanov
0 siblings, 0 replies; 2+ messages in thread
From: Alexey Skidanov @ 2018-02-05 13:46 UTC (permalink / raw)
To: linux-mm, labbott
On 02/05/2018 12:58 AM, Alexey Skidanov wrote:
> Hello,
>
> On x86 machine with 16GB RAM installed, I reserved 1 GB area for CMA:
> [ 0.000000] cma: Reserved 1024 MiB at 0x00000003fcc00000
>
> Some time after the boot, CMa failed to allocate chunk of memory while
> there are enough contiguous pages:
>
> [ 392.132392] cma: cma_alloc: alloc failed, req-size: 200000 pages,
> ret: -16
> [ 392.132393] cma: number of available pages:
> 6@8314+9@8343+9@8375+253648@8496=> 253672 free of 262144 total pages
> [ 392.132398] cma: cma_alloc(): returned (null)
>
> What are the possible reasons for such failure (besides the pinned user
> allocated pages) ?
>
> Thanks,
> Alexey
>
After some debugging - the page migration failed because of there is the
page with _refcount 2, _mapcount -1. Seems like it's pinned?
Thanks,
Alexey
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