diff mbox series

[v4,3/4] sock: Fix misuse of sk_under_memory_pressure()

Message ID 20230530114011.13368-4-wuyun.abel@bytedance.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series sock: Improve condition on sockmem pressure | expand

Checks

Context Check Description
netdev/series_format warning Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 2519 this patch: 2519
netdev/cc_maintainers fail 2 blamed authors not CCed: kamezawa.hiroyu@jp.fujtsu.com glommer@parallels.com; 4 maintainers not CCed: kamezawa.hiroyu@jp.fujtsu.com kuniyu@amazon.com glommer@parallels.com martin.lau@kernel.org
netdev/build_clang success Errors and warnings before: 543 this patch: 543
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 2671 this patch: 2671
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 28 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Abel Wu May 30, 2023, 11:40 a.m. UTC 
The status of global socket memory pressure is updated when:

  a) __sk_mem_raise_allocated():

	enter: sk_memory_allocated(sk) >  sysctl_mem[1]
	leave: sk_memory_allocated(sk) <= sysctl_mem[0]

  b) __sk_mem_reduce_allocated():

	leave: sk_under_memory_pressure(sk) &&
		sk_memory_allocated(sk) < sysctl_mem[0]

So the conditions of leaving global pressure are inconstant, which
may lead to the situation that one pressured net-memcg prevents the
global pressure from being cleared when there is indeed no global
pressure, thus the global constrains are still in effect unexpectedly
on the other sockets.

This patch fixes this by ignoring the net-memcg's pressure when
deciding whether should leave global memory pressure.

Fixes: e1aab161e013 ("socket: initial cgroup code.")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
---
 include/net/sock.h | 9 +++++++--
 net/core/sock.c    | 2 +-
 2 files changed, 8 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/include/net/sock.h b/include/net/sock.h
index b0e5533e5909..257706710be5 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1409,13 +1409,18 @@  static inline bool sk_has_memory_pressure(const struct sock *sk)
 	return sk->sk_prot->memory_pressure != NULL;
 }
 
+static inline bool sk_under_global_memory_pressure(const struct sock *sk)
+{
+	return sk->sk_prot->memory_pressure &&
+		*sk->sk_prot->memory_pressure;
+}
+
 static inline bool sk_under_memory_pressure(const struct sock *sk)
 {
 	if (mem_cgroup_under_socket_pressure(sk->sk_memcg))
 		return true;
 
-	return sk->sk_prot->memory_pressure &&
-		*sk->sk_prot->memory_pressure;
+	return sk_under_global_memory_pressure(sk);
 }
 
 static inline long
diff --git a/net/core/sock.c b/net/core/sock.c
index 5440e67bcfe3..801df091e37a 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3095,7 +3095,7 @@  void __sk_mem_reduce_allocated(struct sock *sk, int amount)
 	if (mem_cgroup_sockets_enabled && sk->sk_memcg)
 		mem_cgroup_uncharge_skmem(sk->sk_memcg, amount);
 
-	if (sk_under_memory_pressure(sk) &&
+	if (sk_under_global_memory_pressure(sk) &&
 	    (sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)))
 		sk_leave_memory_pressure(sk);
 }