From: Abel Wu wuyun.abel@bytedance.com

mainline inclusion from mainline-v6.6-rc1 commit ac8a52962164a50e693fa021d3564d7745b83a7f category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9RB5N

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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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: 8e8ae645249b ("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

Conflicts: include/linux/memcontrol.h mm/vmpressure.c [mm/vmpressure.c: whether mem_cgroup_disabled or not was added] Signed-off-by: Chen Ridong chenridong@huawei.com --- include/linux/memcontrol.h | 9 +++++++-- mm/vmpressure.c | 12 +++++++++++- 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 287c54141a90..e037606be428 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -337,6 +337,11 @@ 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 */ @@ -1978,8 +1983,8 @@ 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; diff --git a/mm/vmpressure.c b/mm/vmpressure.c index c6a7eca666f6..2bd234476635 100644 --- a/mm/vmpressure.c +++ b/mm/vmpressure.c @@ -240,7 +240,17 @@ static void vmpressure_work_fn(struct work_struct *work) void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree, unsigned long scanned, unsigned long reclaimed) { - struct vmpressure *vmpr = memcg_to_vmpressure(memcg); + struct vmpressure *vmpr; + + /* + * 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);

/* * Here we only want to account pressure that userland is able to