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net-memcg: Fix scope of sockmem pressure indicators

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Now there are two indicators of socket memory pressure sit inside
struct mem_cgroup, socket_pressure and tcpmem_pressure, indicating
memory reclaim pressure in memcg->memory and ->tcpmem respectively.

When in legacy mode (cgroupv1), the socket memory is charged into
->tcpmem which is independent of ->memory, so socket_pressure has
nothing to do with socket's pressure at all. Things could be worse
by taking socket_pressure into consideration in legacy mode, as a
pressure in ->memory can lead to premature reclamation/throttling
in socket.

While for the default mode (cgroupv2), the socket memory is charged
into ->memory, and ->tcpmem/->tcpmem_pressure are simply not used.

So {socket,tcpmem}_pressure are only used in default/legacy mode
respectively for indicating socket memory pressure. This patch fixes
the pieces of code that make mixed use of both.

Fixes: 8e8ae64524 ("mm: memcontrol: hook up vmpressure to socket pressure")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Abel Wu 2023-08-14 15:09:11 +08:00 committed by David S. Miller
parent 7fd034bce6
commit ac8a529621
2 changed files with 15 additions and 2 deletions
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9
include/linux/memcontrol.h
View File

@ -284,6 +284,11 @@ struct mem_cgroup {
atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
atomic_long_t memory_events_local[MEMCG_NR_MEMORY_EVENTS];
/*
* Hint of reclaim pressure for socket memroy management. Note
* that this indicator should NOT be used in legacy cgroup mode
* where socket memory is accounted/charged separately.
*/
unsigned long socket_pressure;
/* Legacy tcp memory accounting */
@ -1727,8 +1732,8 @@ void mem_cgroup_sk_alloc(struct sock *sk);
void mem_cgroup_sk_free(struct sock *sk);
static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
{
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && memcg->tcpmem_pressure)
return true;
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
return !!memcg->tcpmem_pressure;
do {
if (time_before(jiffies, READ_ONCE(memcg->socket_pressure)))
return true;

8
mm/vmpressure.c
View File

@ -244,6 +244,14 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
if (mem_cgroup_disabled())
return;
/*
* The in-kernel users only care about the reclaim efficiency
* for this @memcg rather than the whole subtree, and there
* isn't and won't be any in-kernel user in a legacy cgroup.
*/
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !tree)
return;
vmpr = memcg_to_vmpressure(memcg);
/*