Message-ID: <a5bbe855-2980-0e99-dbf6-6f860bffe491@oracle.com>
Date:   Thu, 23 Dec 2021 09:01:38 -0600
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Subject: Re: [PATCH v4 3/3] mm/page_alloc.c: do not warn allocation failure on
 zone DMA if no managed pages
Content-Language: en-US
To:     Baoquan He <bhe@redhat.com>, linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, akpm@linux-foundation.org, hch@lst.de,
        cl@linux.com, kexec@lists.infradead.org, 42.hyeyoo@gmail.com,
        penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com,
        vbabka@suse.cz, David.Laight@ACULAB.COM, david@redhat.com,
        x86@kernel.org, bp@alien8.de,
        John Donnelly <john.p.donnelly@oracle.com>
References: <20211223094435.248523-1-bhe@redhat.com>
 <20211223094435.248523-4-bhe@redhat.com>
From:   john.p.donnelly@oracle.com
In-Reply-To: <20211223094435.248523-4-bhe@redhat.com>
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On 12/23/21 3:44 AM, Baoquan He wrote:
> In kdump kernel of x86_64, page allocation failure is observed:
> 
>   kworker/u2:2: page allocation failure: order:0, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
>   CPU: 0 PID: 55 Comm: kworker/u2:2 Not tainted 5.16.0-rc4+ #5
>   Hardware name: AMD Dinar/Dinar, BIOS RDN1505B 06/05/2013
>   Workqueue: events_unbound async_run_entry_fn
>   Call Trace:
>    <TASK>
>    dump_stack_lvl+0x48/0x5e
>    warn_alloc.cold+0x72/0xd6
>    __alloc_pages_slowpath.constprop.0+0xc69/0xcd0
>    __alloc_pages+0x1df/0x210
>    new_slab+0x389/0x4d0
>    ___slab_alloc+0x58f/0x770
>    __slab_alloc.constprop.0+0x4a/0x80
>    kmem_cache_alloc_trace+0x24b/0x2c0
>    sr_probe+0x1db/0x620
>    ......
>    device_add+0x405/0x920
>    ......
>    __scsi_add_device+0xe5/0x100
>    ata_scsi_scan_host+0x97/0x1d0
>    async_run_entry_fn+0x30/0x130
>    process_one_work+0x1e8/0x3c0
>    worker_thread+0x50/0x3b0
>    ? rescuer_thread+0x350/0x350
>    kthread+0x16b/0x190
>    ? set_kthread_struct+0x40/0x40
>    ret_from_fork+0x22/0x30
>    </TASK>
>   Mem-Info:
>   ......
> 
> The above failure happened when calling kmalloc() to allocate buffer with
> GFP_DMA. It requests to allocate slab page from DMA zone while no managed
> pages at all in there.
>   sr_probe()
>   --> get_capabilities()
>       --> buffer = kmalloc(512, GFP_KERNEL | GFP_DMA);
> 
> Because in the current kernel, dma-kmalloc will be created as long as
> CONFIG_ZONE_DMA is enabled. However, kdump kernel of x86_64 doesn't have
> managed pages on DMA zone since commit 6f599d84231f ("x86/kdump: Always
> reserve the low 1M when the crashkernel option is specified"). The failure
> can be always reproduced.
> 
> For now, let's mute the warning of allocation failure if requesting pages
> from DMA zone while no managed pages.
> 
> Fixes: 6f599d84231f ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified")
> Cc: stable@vger.kernel.org
> Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: John Donnelly  <john.p.donnelly@oracle.com>


> Cc: Christoph Lameter <cl@linux.com>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> ---
>   mm/page_alloc.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 7c7a0b5de2ff..843bc8e5550a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4204,7 +4204,8 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
>   	va_list args;
>   	static DEFINE_RATELIMIT_STATE(nopage_rs, 10*HZ, 1);
>   
> -	if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs))
> +	if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) ||
> +		(gfp_mask & __GFP_DMA) && !has_managed_dma())
>   		return;
>   
>   	va_start(args, fmt);