Re: [PATCH v2] dma-buf: system_heap: do not warn for costly allocation

John Stultz
2021-03-04T19:18:11Z

On Wed, Feb 10, 2021 at 6:33 PM Minchan Kim <minchan@kernel.org> wrote:
>
> Dmabuf system_heap allocation logic starts with the highest necessary
> allocation order before falling back to lower orders. The requested
> order can be higher than PAGE_ALLOC_COSTLY_ODER and failures to
> allocate will flood dmesg with warnings. Such high-order allocations
> are not unexpected and are handled by the system_heap's allocation
> fallback mechanism.
> Prevent these warnings when allocating higher than
> PAGE_ALLOC_COSTLY_ODER pages using __GFP_NOWARN flag.
>
> Below is ION warning example I got but dmabuf system heap is nothing different:
>
> [ 1233.911533][ T460] warn_alloc: 11 callbacks suppressed
> [ 1233.911539][ T460] allocator@2.0-s: page allocation failure: order:4, mode:0x140dc2(GFP_HIGHUSER|__GFP_COMP|__GFP_ZERO), nodemask=(null),cpuset=/,mems_allowed=0
> [ 1233.926235][ T460] Call trace:
> [ 1233.929370][ T460] dump_backtrace+0x0/0x1d8
> [ 1233.933704][ T460] show_stack+0x18/0x24
> [ 1233.937701][ T460] dump_stack+0xc0/0x140
> [ 1233.941783][ T460] warn_alloc+0xf4/0x148
> [ 1233.945862][ T460] __alloc_pages_slowpath+0x9fc/0xa10
> [ 1233.951101][ T460] __alloc_pages_nodemask+0x278/0x2c0
> [ 1233.956285][ T460] ion_page_pool_alloc+0xd8/0x100
> [ 1233.961144][ T460] ion_system_heap_allocate+0xbc/0x2f0
> [ 1233.966440][ T460] ion_buffer_create+0x68/0x274
> [ 1233.971130][ T460] ion_buffer_alloc+0x8c/0x110
> [ 1233.975733][ T460] ion_dmabuf_alloc+0x44/0xe8
> [ 1233.980248][ T460] ion_ioctl+0x100/0x320
> [ 1233.984332][ T460] __arm64_sys_ioctl+0x90/0xc8
> [ 1233.988934][ T460] el0_svc_common+0x9c/0x168
> [ 1233.993360][ T460] do_el0_svc+0x1c/0x28
> [ 1233.997358][ T460] el0_sync_handler+0xd8/0x250
> [ 1234.001989][ T460] el0_sync+0x148/0x180
>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
> * from v1 - https://lore.kernel.org/lkml/20210210162632.3903128-1-minchan@kernel.org/
> * better description - surenb
> * use mid_order_gfp - john.stultz
>
> drivers/dma-buf/heaps/system_heap.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> index 29e49ac17251..e5f545ada587 100644
> --- a/drivers/dma-buf/heaps/system_heap.c
> +++ b/drivers/dma-buf/heaps/system_heap.c
> @@ -40,11 +40,16 @@ struct dma_heap_attachment {
> bool mapped;
> };
>
> +#define LOW_ORDER_GFP (GFP_HIGHUSER | __GFP_ZERO | __GFP_COMP)
> +/*
> + * Avoid warning on order-4 allocation failures as we'll fall back to
> + * order-0 in that case.
> + */
> +#define MID_ORDER_GFP (LOW_ORDER_GFP | __GFP_NOWARN)
> #define HIGH_ORDER_GFP (((GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN \
> | __GFP_NORETRY) & ~__GFP_RECLAIM) \
> | __GFP_COMP)
> -#define LOW_ORDER_GFP (GFP_HIGHUSER | __GFP_ZERO | __GFP_COMP)
> -static gfp_t order_flags[] = {HIGH_ORDER_GFP, LOW_ORDER_GFP, LOW_ORDER_GFP};
> +static gfp_t order_flags[] = {HIGH_ORDER_GFP, MID_ORDER_GFP, LOW_ORDER_GFP};
> /*
> * The selection of the orders used for allocation (1MB, 64K, 4K) is designed
> * to match with the sizes often found in IOMMUs. Using order 4 pages instead

This looks good to me! Thanks for sending this and apologies for the
slow reply, the patch slipped by me!

Reviewed-by: John Stultz <john.stultz@linaro.org>

thanks again!
-john