From f3a53a3a1e5b3b9bc114b5b7930fbe89d9ffed5d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 7 Jun 2018 17:05:35 -0700 Subject: mm, memcontrol: implement memory.swap.events Add swap max and fail events so that userland can monitor and respond to running out of swap. I'm not too sure about the fail event. Right now, it's a bit confusing which stats / events are recursive and which aren't and also which ones reflect events which originate from a given cgroup and which targets the cgroup. No idea what the right long term solution is and it could just be that growing them organically is actually the only right thing to do. Link: http://lkml.kernel.org/r/20180416231151.GI1911913@devbig577.frc2.facebook.com Signed-off-by: Tejun Heo Reviewed-by: Andrew Morton Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Roman Gushchin Cc: Rik van Riel Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e8166521a474..d86665cf4a49 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6012,13 +6012,17 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) if (!memcg) return 0; - if (!entry.val) + if (!entry.val) { + memcg_memory_event(memcg, MEMCG_SWAP_FAIL); return 0; + } memcg = mem_cgroup_id_get_online(memcg); if (!mem_cgroup_is_root(memcg) && !page_counter_try_charge(&memcg->swap, nr_pages, &counter)) { + memcg_memory_event(memcg, MEMCG_SWAP_MAX); + memcg_memory_event(memcg, MEMCG_SWAP_FAIL); mem_cgroup_id_put(memcg); return -ENOMEM; } @@ -6156,6 +6160,18 @@ static ssize_t swap_max_write(struct kernfs_open_file *of, return nbytes; } +static int swap_events_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + + seq_printf(m, "max %lu\n", + atomic_long_read(&memcg->memory_events[MEMCG_SWAP_MAX])); + seq_printf(m, "fail %lu\n", + atomic_long_read(&memcg->memory_events[MEMCG_SWAP_FAIL])); + + return 0; +} + static struct cftype swap_files[] = { { .name = "swap.current", @@ -6168,6 +6184,12 @@ static struct cftype swap_files[] = { .seq_show = swap_max_show, .write = swap_max_write, }, + { + .name = "swap.events", + .flags = CFTYPE_NOT_ON_ROOT, + .file_offset = offsetof(struct mem_cgroup, swap_events_file), + .seq_show = swap_events_show, + }, { } /* terminate */ }; -- cgit v1.2.3-58-ga151