[PATCH] coresight: tmc-etr: Disable warnings for allocation failures

[James Clark]

On 17/08/2023 17:19, Suzuki K Poulose wrote:
> Running the following command on Juno triggers the warning:
> 
>  $ perf record -e cs_etm// -m ,128M ...
> 
>  ------------[ cut here ]------------
>  WARNING: CPU: 1 PID: 412 at mm/page_alloc.c:4453 __alloc_pages+0x334/0x1420
>  CPU: 1 PID: 412 Comm: perf Not tainted 6.5.0-rc3+ #181
>  Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb  1 2019
>  pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>  pc : __alloc_pages+0x334/0x1420
>  lr : dma_common_alloc_pages+0x108/0x138
>  sp : ffffffc087fb7440
>  x29: ffffffc087fb7440 x28: 0000000000000000 x27: ffffffc07e48fba0
>  x26: 0000000000000001 x25: 000000000000000f x24: ffffffc081f24880
>  x23: 0000000000000cc0 x22: ffffff88012b6f08 x21: 0000000008000000
>  x20: ffffff8801433000 x19: 0000000000000000 x18: 0000000000000000
>  x17: ffffffc080316e5c x16: ffffffc07e46406c x15: ffffffc0803af580
>  x14: ffffffc08036b460 x13: ffffffc080025cbc x12: ffffffb8108c3fc4
>  x11: 1ffffff8108c3fc3 x10: 1ffffff810ff6eac x9 : 00000000f204f204
>  x8 : 000000000000f204 x7 : 00000000f2f2f2f2 x6 : 00000000f3f3f3f3
>  x5 : 0000000000000001 x4 : 0000000000000000 x3 : 0000000000000000
>  x2 : 0000000000000cc0 x1 : 0000000000000000 x0 : ffffffc085333000
>  Call trace:
>   __alloc_pages+0x334/0x1420
>   dma_common_alloc_pages+0x108/0x138
>   __dma_alloc_pages+0xf4/0x108
>   dma_alloc_pages+0x18/0x30
>   tmc_etr_alloc_flat_buf+0xa0/0x190 [coresight_tmc]
>   tmc_alloc_etr_buf.constprop.0+0x124/0x298 [coresight_tmc]
>   alloc_etr_buf.constprop.0.isra.0+0x88/0xc8 [coresight_tmc]
>   tmc_alloc_etr_buffer+0x164/0x2f0 [coresight_tmc]
>   etm_setup_aux+0x32c/0x520 [coresight]
>   rb_alloc_aux+0x29c/0x3f8
>   perf_mmap+0x59c/0xce0
>   mmap_region+0x340/0x10e0
>   do_mmap+0x48c/0x580
>   vm_mmap_pgoff+0x160/0x248
>   ksys_mmap_pgoff+0x1e8/0x278
>   __arm64_sys_mmap+0x8c/0xb8
> 
> With the flat mode, we only attempt to allocate large memory if there is an IOMMU
> connected to the ETR. If the allocation fails, we always have a fallback path
> and return an error if nothing else worked. So, suppress the warning for flat
> mode allocations.
> 
> Cc: Mike Leach <mike.leach at linaro.org>
> Cc: James Clark <james.clark at arm.com>
> Cc: Anshuman Khandual <anshuman.khandual at arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose at arm.com>

Reviewed-by: James Clark <james.clark at arm.com>

> ---
>  drivers/hwtracing/coresight/coresight-tmc-etr.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 66dc5f97a009..c8df8719f6a0 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -610,7 +610,8 @@ static int tmc_etr_alloc_flat_buf(struct tmc_drvdata *drvdata,
>  
>  	flat_buf->vaddr = dma_alloc_noncoherent(real_dev, etr_buf->size,
>  						&flat_buf->daddr,
> -						DMA_FROM_DEVICE, GFP_KERNEL);
> +						DMA_FROM_DEVICE,
> +						GFP_KERNEL | __GFP_NOWARN);
>  	if (!flat_buf->vaddr) {
>  		kfree(flat_buf);
>  		return -ENOMEM;