linux-kernel - [PATCH net-next v2] Fix sock_exceed_buf_limit not being triggered in __sk_mem_raise

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Message-Id: <20250527030419.67693-1-yangtengteng@bytedance.com>
Date: Tue, 27 May 2025 11:04:19 +0800
From: <yangtengteng@...edance.com>
To: edumazet@...gle.com,
	kuniyu@...zon.com,
	pabeni@...hat.com,
	willemb@...gle.com,
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Cc: netdev@...r.kernel.org,
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	zhoufeng.zf@...edance.com,
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	yangtengteng@...edance.com
Subject: [PATCH net-next v2] Fix sock_exceed_buf_limit not being triggered in __sk_mem_raise_allocated

From: Tengteng Yang <yangtengteng@...edance.com>

When a process under memory pressure is not part of any cgroup and
the charged flag is false, trace_sock_exceed_buf_limit was not called
as expected.

This regression was introduced by commit 2def8ff3fdb6 ("sock:
Code cleanup on __sk_mem_raise_allocated()"). The fix changes the
default value of charged to true while preserving existing logic.

Fixes: 2def8ff3fdb6 ("sock: Code cleanup on __sk_mem_raise_allocated()")
Signed-off-by: Abel Wu <wuyun.abel@...edance.com>
Signed-off-by: Tengteng Yang <yangtengteng@...edance.com>
---
v1:
- Fix compilation error caused by mismatched parentheses
---
 net/core/sock.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 347ce75482f5..9cfed4635d81 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3235,16 +3235,16 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
 {
 	struct mem_cgroup *memcg = mem_cgroup_sockets_enabled ? sk->sk_memcg : NULL;
 	struct proto *prot = sk->sk_prot;
-	bool charged = false;
+	bool charged = true;
 	long allocated;
 
 	sk_memory_allocated_add(sk, amt);
 	allocated = sk_memory_allocated(sk);
 
 	if (memcg) {
-		if (!mem_cgroup_charge_skmem(memcg, amt, gfp_memcg_charge()))
+		charged = mem_cgroup_charge_skmem(memcg, amt, gfp_memcg_charge());
+		if (!charged)
 			goto suppress_allocation;
-		charged = true;
 	}
 
 	/* Under limit. */
@@ -3329,7 +3329,7 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
 
 	sk_memory_allocated_sub(sk, amt);
 
-	if (charged)
+	if (memcg && charged)
 		mem_cgroup_uncharge_skmem(memcg, amt);
 
 	return 0;
-- 
2.20.1