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From: Michal Hocko <mhocko@kernel.org>
To: Qian Cai <cai@lca.pw>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	davem@davemloft.net, netdev@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] net/skbuff: silence warnings under memory pressure
Date: Wed, 4 Sep 2019 08:15:01 +0200	[thread overview]
Message-ID: <20190904061501.GB3838@dhcp22.suse.cz> (raw)
In-Reply-To: <1567546948.5576.68.camel@lca.pw>

Cc printk maintainers

On Tue 03-09-19 17:42:28, Qian Cai wrote:
> > > I suppose what happens is those skb_build() allocations are from softirq,
> > > and
> > > once one of them failed, it calls printk() which generates more interrupts.
> > > Hence, the infinite loop.
> > 
> > Please elaborate more.
> > 
> 
> If you look at the original report, the failed allocation dump_stack() is,
> 
>  <IRQ>
>  warn_alloc.cold.43+0x8a/0x148
>  __alloc_pages_nodemask+0x1a5c/0x1bb0
>  alloc_pages_current+0x9c/0x110
>  allocate_slab+0x34a/0x11f0
>  new_slab+0x46/0x70
>  ___slab_alloc+0x604/0x950
>  __slab_alloc+0x12/0x20
>  kmem_cache_alloc+0x32a/0x400
>  __build_skb+0x23/0x60
>  build_skb+0x1a/0xb0
>  igb_clean_rx_irq+0xafc/0x1010 [igb]
>  igb_poll+0x4bb/0xe30 [igb]
>  net_rx_action+0x244/0x7a0
>  __do_softirq+0x1a0/0x60a
>  irq_exit+0xb5/0xd0
>  do_IRQ+0x81/0x170
>  common_interrupt+0xf/0xf
>  </IRQ>
> 
> Since it has no __GFP_NOWARN to begin with, it will call,
> 
> printk
>   vprintk_default
>     vprintk_emit
>       wake_up_klogd
>         irq_work_queue
>           __irq_work_queue_local
>             arch_irq_work_raise
>               apic->send_IPI_self(IRQ_WORK_VECTOR)
>                 smp_irq_work_interrupt
>                   exiting_irq
>                     irq_exit
> 
> and end up processing pending net_rx_action softirqs again which are plenty due
> to connected via ssh etc.
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2019-09-04  6:15 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-30 14:57 [PATCH] net/skbuff: silence warnings under memory pressure Qian Cai
2019-08-30 15:11 ` Eric Dumazet
2019-08-30 15:25   ` Qian Cai
2019-08-30 16:15     ` Eric Dumazet
2019-08-30 18:06       ` Qian Cai
2019-09-03 13:22       ` Michal Hocko
2019-09-03 15:42         ` Qian Cai
2019-09-03 18:53           ` Michal Hocko
2019-09-03 21:42             ` Qian Cai
2019-09-04  6:15               ` Michal Hocko [this message]
2019-09-04  6:41                 ` Sergey Senozhatsky
2019-09-04  6:54                   ` Michal Hocko
2019-09-04  7:19                     ` Sergey Senozhatsky
2019-09-04  7:43                       ` Sergey Senozhatsky
2019-09-04 12:14                         ` Qian Cai
2019-09-04 14:48                           ` Sergey Senozhatsky
2019-09-04 15:07                             ` Qian Cai
2019-09-04 20:42                             ` Qian Cai
2019-09-05  8:32                               ` Eric Dumazet
2019-09-05 14:09                                 ` Qian Cai
2019-09-05 15:06                                   ` Eric Dumazet
2019-09-05 15:14                                   ` Eric Dumazet
2019-09-05 11:32                               ` Sergey Senozhatsky
2019-09-05 16:03                                 ` Qian Cai
2019-09-05 17:14                                   ` Steven Rostedt
2019-09-06  2:50                                     ` Sergey Senozhatsky
2019-09-06  4:32                                   ` Sergey Senozhatsky
2019-09-06 21:17                                     ` Qian Cai
2019-09-05 17:23                                 ` Steven Rostedt
2019-09-06  3:39                                   ` Sergey Senozhatsky
2019-09-06 15:32                                     ` Petr Mladek
2019-09-09  1:10                                       ` Sergey Senozhatsky
2019-09-06 14:55                                 ` Petr Mladek
2019-09-06 19:51                                   ` Sergey Senozhatsky
2019-11-14 17:12                                 ` Qian Cai
2019-11-18 15:27                                   ` Petr Mladek
2019-11-19  0:41                                     ` Sergey Senozhatsky
2019-11-19  9:41                                       ` Petr Mladek
2019-11-19 15:58                                         ` Qian Cai
2019-11-20  1:30                                         ` Sergey Senozhatsky
2019-11-20 16:13                                           ` Petr Mladek
2019-11-21  1:05                                             ` Sergey Senozhatsky
2019-11-21  9:15                                               ` Petr Mladek
2019-09-04  7:00                   ` Sergey Senozhatsky
2019-09-04  8:25                     ` Michal Hocko
2019-09-04 11:59                       ` Qian Cai
2019-09-04 12:07                         ` Michal Hocko
2019-09-04 12:28                           ` Qian Cai
2019-09-07 11:00                       ` Tetsuo Handa
2019-09-04  6:15               ` Michal Hocko
2019-09-02 14:24     ` Vlastimil Babka

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