From: Jakub Kicinski <kuba@kernel.org>
To: Shakeel Butt <shakeelb@google.com>
Cc: Wei Wang <weiwan@google.com>, Eric Dumazet <edumazet@google.com>,
netdev@vger.kernel.org, "David S . Miller" <davem@davemloft.net>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
Roman Gushchin <roman.gushchin@linux.dev>
Subject: Re: [PATCH net-next] net-memcg: pass in gfp_t mask to mem_cgroup_charge_skmem()
Date: Wed, 12 Oct 2022 17:38:25 -0700 [thread overview]
Message-ID: <20221012173825.45d6fbf2@kernel.org> (raw)
In-Reply-To: <CALvZod5pKzcxWsLnjUwE9fUb=1S9MDLOHF950miF8x8CWtK5Bw@mail.gmail.com>
On Wed, 12 Oct 2022 17:17:38 -0700 Shakeel Butt wrote:
> Did the revert of this patch fix the issue you are seeing? The reason
> I am asking is because this patch should not change the behavior.
> Actually someone else reported the similar issue for UDP RX at [1] and
> they tested the revert as well. The revert did not fix the issue for
> them.
>
> Wei has a better explanation at [2] why this patch is not the cause
> for these issues.
We're talking TCP here, to be clear. I haven't tested a revert, yet (not
that easy to test with a real workload) but I'm relatively confident the
change did introduce an "unforced" call, specifically this bit:
@@ -2728,10 +2728,12 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
{
struct proto *prot = sk->sk_prot;
long allocated = sk_memory_allocated_add(sk, amt);
+ bool memcg_charge = mem_cgroup_sockets_enabled && sk->sk_memcg;
bool charged = true;
- if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
- !(charged = mem_cgroup_charge_skmem(sk->sk_memcg, amt)))
+ if (memcg_charge &&
+ !(charged = mem_cgroup_charge_skmem(sk->sk_memcg, amt,
+ gfp_memcg_charge())))
where gfp_memcg_charge() is GFP_NOWAIT in softirq.
The above gets called from (inverted stack):
tcp_data_queue()
tcp_try_rmem_schedule(sk, skb, skb->truesize)
tcp_try_rmem_schedule()
sk_rmem_schedule()
__sk_mem_schedule()
__sk_mem_raise_allocated()
Is my confidence unjustified? :)
next prev parent reply other threads:[~2022-10-13 0:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-17 19:40 [PATCH net-next] net-memcg: pass in gfp_t mask to mem_cgroup_charge_skmem() Wei Wang
2021-08-18 10:50 ` patchwork-bot+netdevbpf
2022-10-12 23:33 ` Jakub Kicinski
2022-10-13 0:17 ` Shakeel Butt
2022-10-13 0:38 ` Jakub Kicinski [this message]
2022-10-13 0:54 ` Shakeel Butt
2022-10-13 1:40 ` Jakub Kicinski
2022-10-13 3:16 ` Jakub Kicinski
2022-10-13 3:34 ` Wei Wang
2022-10-13 3:49 ` Jakub Kicinski
2022-10-13 4:04 ` Wei Wang
2022-10-13 4:18 ` Shakeel Butt
2022-10-13 21:49 ` Jakub Kicinski
2022-10-13 22:02 ` Eric Dumazet
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