On 10/4/17 7:27 AM, Michal Hocko wrote:
On Wed 04-10-17 02:06:17, Yang Shi wrote:+static bool is_dump_unreclaim_slabs(void) +{ + unsigned long nr_lru; + + nr_lru = global_node_page_state(NR_ACTIVE_ANON) + + global_node_page_state(NR_INACTIVE_ANON) + + global_node_page_state(NR_ACTIVE_FILE) + + global_node_page_state(NR_INACTIVE_FILE) + + global_node_page_state(NR_ISOLATED_ANON) + + global_node_page_state(NR_ISOLATED_FILE) + + global_node_page_state(NR_UNEVICTABLE); + + return (global_node_page_state(NR_SLAB_UNRECLAIMABLE) > nr_lru); +}I am sorry I haven't pointed this earlier (I was following only half way) but this should really be memcg aware. You are checking only global counters. I do not think it is an absolute must to provide per-memcg data but you should at least check !is_memcg_oom(oc).
OK, sure.
[...]+void dump_unreclaimable_slab(void) +{ + struct kmem_cache *s, *s2; + struct slabinfo sinfo; + + pr_info("Unreclaimable slab info:\n"); + pr_info("Name Used Total\n"); + + /* + * Here acquiring slab_mutex is risky since we don't prefer to get + * sleep in oom path. But, without mutex hold, it may introduce a + * risk of crash. + * Use mutex_trylock to protect the list traverse, dump nothing + * without acquiring the mutex. + */ + if (!mutex_trylock(&slab_mutex)) + return;I would move the trylock up so that we do not get empty and confusing Unreclaimable slab info: and add a note that we are not dumping anything due to lock contention pr_warn("excessive unreclaimable slab memory but cannot dump stats to give you more details\n");
Thanks for pointing this. Will fix in new version. Yang
Other than that this looks sensible to me.+ list_for_each_entry_safe(s, s2, &slab_caches, list) { + if (!is_root_cache(s) || (s->flags & SLAB_RECLAIM_ACCOUNT)) + continue; + + memset(&sinfo, 0, sizeof(sinfo)); + get_slabinfo(s, &sinfo); + + if (sinfo.num_objs > 0) + pr_info("%-17s %10luKB %10luKB\n", cache_name(s), + (sinfo.active_objs * s->size) / 1024, + (sinfo.num_objs * s->size) / 1024); + } + mutex_unlock(&slab_mutex); +} + #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) void *memcg_slab_start(struct seq_file *m, loff_t *pos) { -- 1.8.3.1
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