Re: [PATCH] dma/pool: do not complain if DMA pool is not allocated

Baoquan He
2022-08-10T02:25:18Z

On 08/09/22 at 05:37pm, Michal Hocko wrote:
> Here we go again.
> ---
> From 1dc9d7504624b273de47a88a9907f43533bfe08e Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@suse.com>
> Date: Fri, 25 Mar 2022 13:25:59 +0100
> Subject: [PATCH] dma/pool: do not complain if DMA pool is not allocated
>
> we have a system complainging about order-10 allocation for the DMA pool.
>
> [ 14.017417][ T1] swapper/0: page allocation failure: order:10, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0-7
> [ 14.017429][ T1] CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.14.21-150400.22-default #1 SLE15-SP4 0b6a6578ade2de5c4a0b916095dff44f76ef1704
> [ 14.017434][ T1] Hardware name: XXXX
> [ 14.017437][ T1] Call Trace:
> [ 14.017444][ T1] <TASK>
> [ 14.017449][ T1] dump_stack_lvl+0x45/0x57
> [ 14.017469][ T1] warn_alloc+0xfe/0x160
> [ 14.017490][ T1] __alloc_pages_slowpath.constprop.112+0xc27/0xc60
> [ 14.017497][ T1] ? rdinit_setup+0x2b/0x2b
> [ 14.017509][ T1] ? rdinit_setup+0x2b/0x2b
> [ 14.017512][ T1] __alloc_pages+0x2d5/0x320
> [ 14.017517][ T1] alloc_page_interleave+0xf/0x70
> [ 14.017531][ T1] atomic_pool_expand+0x4a/0x200
> [ 14.017541][ T1] ? rdinit_setup+0x2b/0x2b
> [ 14.017544][ T1] __dma_atomic_pool_init+0x44/0x90
> [ 14.017556][ T1] dma_atomic_pool_init+0xad/0x13f
> [ 14.017560][ T1] ? __dma_atomic_pool_init+0x90/0x90
> [ 14.017562][ T1] do_one_initcall+0x41/0x200
> [ 14.017581][ T1] kernel_init_freeable+0x236/0x298
> [ 14.017589][ T1] ? rest_init+0xd0/0xd0
> [ 14.017596][ T1] kernel_init+0x16/0x120
> [ 14.017599][ T1] ret_from_fork+0x22/0x30
> [ 14.017604][ T1] </TASK>
> [...]
> [ 14.018026][ T1] Node 0 DMA free:160kB boost:0kB min:0kB low:0kB high:0kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15996kB managed:15360kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
> [ 14.018035][ T1] lowmem_reserve[]: 0 0 0 0 0
> [ 14.018339][ T1] Node 0 DMA: 0*4kB 0*8kB 0*16kB 1*32kB (U) 0*64kB 1*128kB (U) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 160kB
>
> The usable memory in the DMA zone is obviously too small for the pool
> pre-allocation. The allocation failure raises concern by admins because
> this is considered an error state.
>
> In fact the preallocation itself doesn't expose any actual problem. It
> is not even clear whether anybody is ever going to use this pool. If yes
> then a warning will be triggered anyway.
>
> Silence the warning to prevent confusion and bug reports.

LGTM,

Reviewed-by: Baoquan He <bhe@redhat.com>

>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
> kernel/dma/pool.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
> index 4d40dcce7604..1bf6de398986 100644
> --- a/kernel/dma/pool.c
> +++ b/kernel/dma/pool.c
> @@ -205,7 +205,7 @@ static int __init dma_atomic_pool_init(void)
> ret = -ENOMEM;
> if (has_managed_dma()) {
> atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
> - GFP_KERNEL | GFP_DMA);
> + GFP_KERNEL | GFP_DMA | __GFP_NOWARN);
> if (!atomic_pool_dma)
> ret = -ENOMEM;
> }
> --
> 2.30.2
>
> --
> Michal Hocko
> SUSE Labs
>