The interface is slightly reworked to be more v2 like: - rename memory.cache.limit/usage_in_bytes -> memory.cache.max/current - show "max" when uninitialized and allow to write it - memcg_max_mutex with page_counter_set_max replaced with simple xchg - we set limit first before looping and then try to enforce it if needed, no more enforce before setting logic - retry reclaim couple of times if it fails to enforce the limit and then just give up (memory_max_write triggers oom in this case, but we probably do not want to trigger oom due to cache limit)
https://virtuozzo.atlassian.net/browse/PSBM-154207 Signed-off-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com> Feature: mm: Memory cgroup page cache limit --- mm/memcontrol.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9000dc00ed03..28a39b50cbe1 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -8810,3 +8810,78 @@ static int __init mem_cgroup_swap_init(void) subsys_initcall(mem_cgroup_swap_init); #endif /* CONFIG_SWAP */ + +static int cache_max_show(struct seq_file *m, void *v) +{ + return seq_puts_memcg_tunable(m, + READ_ONCE(mem_cgroup_from_seq(m)->cache.max)); +} + +static ssize_t cache_max_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + unsigned int nr_reclaims = MAX_RECLAIM_RETRIES; + unsigned long max; + int err; + + buf = strstrip(buf); + err = page_counter_memparse(buf, "max", &max); + if (err) + return err; + + xchg(&memcg->cache.max, max); + + for (;;) { + unsigned long nr_cache = page_counter_read(&memcg->cache); + + if (nr_cache <= max) + break; + + if (signal_pending(current)) + break; + + if (!nr_reclaims) + break; + + if (!try_to_free_mem_cgroup_pages(memcg, nr_cache - max, + GFP_KERNEL, false)) + nr_reclaims--; + } + + memcg_wb_domain_size_changed(memcg); + return nbytes; +} + +static u64 cache_current_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + return (u64)page_counter_read(&memcg->cache) * PAGE_SIZE; +} + +static struct cftype cache_files[] = { + { + .name = "cache.max", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cache_max_show, + .write = cache_max_write, + }, + { + .name = "cache.current", + .flags = CFTYPE_NOT_ON_ROOT, + .read_u64 = cache_current_read, + }, + { } /* terminate */ +}; + +static int __init mem_cgroup_cache_init(void) +{ + if (mem_cgroup_disabled()) + return 0; + + WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, cache_files)); + return 0; +} +subsys_initcall(mem_cgroup_cache_init); -- 2.43.0 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
