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Date:   Wed, 4 Sep 2019 16:00:42 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Qian Cai <cai@lca.pw>, 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>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH] net/skbuff: silence warnings under memory pressure
Message-ID: <20190904070042.GA11968@jagdpanzerIV>
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On (09/04/19 15:41), Sergey Senozhatsky wrote:
> But the thing is different in case of dump_stack() + show_mem() +
> some other output. Because now we ratelimit not a single printk() line,
> but hundreds of them. The ratelimit becomes - 10 * $$$ lines in 5 seconds
> (IOW, now we talk about thousands of lines).

And on devices with slow serial consoles this can be somewhat close to
"no ratelimit". *Suppose* that warn_alloc() adds 700 lines each time.
Within 5 seconds we can call warn_alloc() 10 times, which will add 7000
lines to the logbuf. If printk() can evict only 6000 lines in 5 seconds
then we have a growing number of pending logbuf messages.

	-ss