Commit ac8a5296 authored by Abel Wu's avatar Abel Wu Committed by David S. Miller
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net-memcg: Fix scope of sockmem pressure indicators 



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: 8e8ae645 ("mm: memcontrol: hook up vmpressure to socket pressure")
Signed-off-by: default avatarAbel Wu <wuyun.abel@bytedance.com>
Acked-by: default avatarShakeel Butt <shakeelb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7fd034bc

include/linux/memcontrol.h

+7 −2
Original line number Diff line number Diff line
@@ -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;

mm/vmpressure.c

+8 −0
Original line number Diff line number Diff line
@@ -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);



	/*