netdev - Re: [PATCH] net/skbuff: silence warnings under memory pressure

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Message-ID: <6109dab4-4061-8fee-96ac-320adf94e130@gmail.com>
Date:   Fri, 30 Aug 2019 17:11:57 +0200
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Qian Cai <cai@....pw>, davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net/skbuff: silence warnings under memory pressure



On 8/30/19 4:57 PM, Qian Cai wrote:
> When running heavy memory pressure workloads, the system is throwing
> endless warnings below due to the allocation could fail from
> __build_skb(), and the volume of this call could be huge which may
> generate a lot of serial console output and cosumes all CPUs as
> warn_alloc() could be expensive by calling dump_stack() and then
> show_mem().
> 
> Fix it by silencing the warning in this call site. Also, it seems
> unnecessary to even print a warning at all if the allocation failed in
> __build_skb(), as it may just retransmit the packet and retry.
> 

Same patches are showing up there and there from time to time.

Why is this particular spot interesting, against all others not adding __GFP_NOWARN ?

Are we going to have hundred of patches adding __GFP_NOWARN at various points,
or should we get something generic to not flood the syslog in case of memory pressure ?