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| author | Abel Wu <wuyun.abel@bytedance.com> | 2023-10-19 15:00:25 +0300 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2023-10-24 11:38:30 +0300 |
| commit | 2e12072c67b5f65fc71a569985a1262531fbdc06 (patch) | |
| tree | 9011790d69df11f53b64403bdfa2bed49e006208 /net/core | |
| parent | 2def8ff3fdb66d10ebe3ec84787799ac0244eb23 (diff) | |
| download | linux-2e12072c67b5f65fc71a569985a1262531fbdc06.tar.xz | |
sock: Doc behaviors for pressure heurisitics
There are now two accounting infrastructures for skmem, while the
heuristics in __sk_mem_raise_allocated() were actually introduced
before memcg was born.
Add some comments to clarify whether they can be applied to both
infrastructures or not.
Suggested-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20231019120026.42215-2-wuyun.abel@bytedance.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/sock.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/net/core/sock.c b/net/core/sock.c index 43842520db86..9f969e3c2ddf 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -3067,7 +3067,14 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind) if (allocated > sk_prot_mem_limits(sk, 2)) goto suppress_allocation; - /* guarantee minimum buffer size under pressure */ + /* Guarantee minimum buffer size under pressure (either global + * or memcg) to make sure features described in RFC 7323 (TCP + * Extensions for High Performance) work properly. + * + * This rule does NOT stand when exceeds global or memcg's hard + * limit, or else a DoS attack can be taken place by spawning + * lots of sockets whose usage are under minimum buffer size. + */ if (kind == SK_MEM_RECV) { if (atomic_read(&sk->sk_rmem_alloc) < sk_get_rmem0(sk, prot)) return 1; @@ -3088,6 +3095,11 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind) if (!sk_under_memory_pressure(sk)) return 1; + + /* Try to be fair among all the sockets under global + * pressure by allowing the ones that below average + * usage to raise. + */ alloc = sk_sockets_allocated_read_positive(sk); if (sk_prot_mem_limits(sk, 2) > alloc * sk_mem_pages(sk->sk_wmem_queued + |