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

On Tue, 2019-09-03 at 15:22 +0200, Michal Hocko wrote:

On Fri 30-08-19 18:15:22, Eric Dumazet wrote:

quoted

If there is a risk of flooding the syslog, we should fix this generically
in mm layer, not adding hundred of __GFP_NOWARN all over the places.

We do already ratelimit in warn_alloc. If it isn't sufficient then we
can think of a different parameters. Or maybe it is the ratelimiting
which doesn't work here. Hard to tell and something to explore.

The time-based ratelimit won't work for skb_build() as when a system under
memory pressure, and the CPU is fast and IO is so slow, it could take a long
time to swap and trigger OOM.

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.