[Cc linux-api] On Mon 17-06-19 10:21:49, Waiman Long wrote: > There are concerns about memory leaks from extensive use of memory > cgroups as each memory cgroup creates its own set of kmem caches. There > is a possiblity that the memcg kmem caches may remain even after the > memory cgroup removal. > > Therefore, it will be useful to show how many memcg caches are present > for each of the kmem caches.
How is a user going to use that information? Btw. Don't we have an interface to display the number of (dead) cgroups? Keeping the rest of the email for the reference. > As slabinfo reporting code has to iterate > through all the memcg caches to get the final numbers anyway, there is > no additional cost in reporting the number of memcg caches available. > > The slabinfo version is bumped up to 2.2 as a new "<num_caches>" column > is added at the end. > > Signed-off-by: Waiman Long <[email protected]> > --- > mm/slab_common.c | 24 ++++++++++++++++-------- > 1 file changed, 16 insertions(+), 8 deletions(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 58251ba63e4a..c7aa47a99b2b 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -1308,13 +1308,13 @@ static void print_slabinfo_header(struct seq_file *m) > * without _too_ many complaints. > */ > #ifdef CONFIG_DEBUG_SLAB > - seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); > + seq_puts(m, "slabinfo - version: 2.2 (statistics)\n"); > #else > - seq_puts(m, "slabinfo - version: 2.1\n"); > + seq_puts(m, "slabinfo - version: 2.2\n"); > #endif > seq_puts(m, "# name <active_objs> <num_objs> <objsize> > <objperslab> <pagesperslab>"); > seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); > - seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); > + seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail> > <num_caches>"); > #ifdef CONFIG_DEBUG_SLAB > seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> > <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); > seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); > @@ -1338,14 +1338,18 @@ void slab_stop(struct seq_file *m, void *p) > mutex_unlock(&slab_mutex); > } > > -static void > +/* > + * Return number of memcg caches. > + */ > +static unsigned int > memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info) > { > struct kmem_cache *c; > struct slabinfo sinfo; > + unsigned int cnt = 0; > > if (!is_root_cache(s)) > - return; > + return 0; > > for_each_memcg_cache(c, s) { > memset(&sinfo, 0, sizeof(sinfo)); > @@ -1356,17 +1360,20 @@ memcg_accumulate_slabinfo(struct kmem_cache *s, > struct slabinfo *info) > info->shared_avail += sinfo.shared_avail; > info->active_objs += sinfo.active_objs; > info->num_objs += sinfo.num_objs; > + cnt++; > } > + return cnt; > } > > static void cache_show(struct kmem_cache *s, struct seq_file *m) > { > struct slabinfo sinfo; > + unsigned int nr_memcg_caches; > > memset(&sinfo, 0, sizeof(sinfo)); > get_slabinfo(s, &sinfo); > > - memcg_accumulate_slabinfo(s, &sinfo); > + nr_memcg_caches = memcg_accumulate_slabinfo(s, &sinfo); > > seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", > cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size, > @@ -1374,8 +1381,9 @@ static void cache_show(struct kmem_cache *s, struct > seq_file *m) > > seq_printf(m, " : tunables %4u %4u %4u", > sinfo.limit, sinfo.batchcount, sinfo.shared); > - seq_printf(m, " : slabdata %6lu %6lu %6lu", > - sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); > + seq_printf(m, " : slabdata %6lu %6lu %6lu %3u", > + sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail, > + nr_memcg_caches); > slabinfo_show_stats(m, s); > seq_putc(m, '\n'); > } > -- > 2.18.1 -- Michal Hocko SUSE Labs
