On Thu, Dec 23, 2021 at 05:44:35PM +0800, 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@xxxxxxxxxxxxxxx
> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> 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;
>
Warning when there's always no page in DMA zone is unnecessary
and it confuses user.
The patch looks good.
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
And there is some driers that allocate memory with GFP_DMA
even if that flag is unnecessary. We need to do cleanup later.
Baoquan Are you planning to do it soon?
I want to help that.
Merry Christmas,
Hyeonggon
> va_start(args, fmt);
> --
> 2.26.3
>
>
