| Message ID | 1562116978-19539-1-git-send-email-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/memcontrol: fix wrong statistics in memory.stat | expand |
+Johannes Weiner On Tue, Jul 2, 2019 at 6:23 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > When we calculate total statistics for memcg1_stats and memcg1_events, we > use the the index 'i' in the for loop as the events index. > Actually we should use memcg1_stats[i] and memcg1_events[i] as the > events index. > > Fixes: 8de7ecc6483b ("memcg: reduce memcg tree traversals for stats collection") Actually it fixes 42a300353577 ("mm: memcontrol: fix recursive statistics correctness & scalabilty"). > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > Cc: Shakeel Butt <shakeelb@google.com> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Yafang Shao <shaoyafang@didiglobal.com> > --- > mm/memcontrol.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 3ee806b..2ad94d0 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3528,12 +3528,13 @@ static int memcg_stat_show(struct seq_file *m, void *v) > if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) > continue; > seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], > - (u64)memcg_page_state(memcg, i) * PAGE_SIZE); > + (u64)memcg_page_state(memcg, memcg1_stats[i]) * > + PAGE_SIZE); It seems like I made the above very subtle in 8de7ecc6483b and Johannes missed this subtlety in 42a300353577 (and I missed it in the review). > } > > for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) > seq_printf(m, "total_%s %llu\n", memcg1_event_names[i], > - (u64)memcg_events(memcg, i)); > + (u64)memcg_events(memcg, memcg1_events[i])); > > for (i = 0; i < NR_LRU_LISTS; i++) > seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], > -- > 1.8.3.1 > Reviewed-by: Shakeel Butt <shakeelb@google.com>
+Johannes for real On Tue, Jul 2, 2019 at 8:50 PM Shakeel Butt <shakeelb@google.com> wrote: > > +Johannes Weiner > > On Tue, Jul 2, 2019 at 6:23 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > > > When we calculate total statistics for memcg1_stats and memcg1_events, we > > use the the index 'i' in the for loop as the events index. > > Actually we should use memcg1_stats[i] and memcg1_events[i] as the > > events index. > > > > Fixes: 8de7ecc6483b ("memcg: reduce memcg tree traversals for stats collection") > > Actually it fixes 42a300353577 ("mm: memcontrol: fix recursive > statistics correctness & scalabilty"). > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > Cc: Shakeel Butt <shakeelb@google.com> > > Cc: Michal Hocko <mhocko@suse.com> > > Cc: Yafang Shao <shaoyafang@didiglobal.com> > > --- > > mm/memcontrol.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 3ee806b..2ad94d0 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -3528,12 +3528,13 @@ static int memcg_stat_show(struct seq_file *m, void *v) > > if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) > > continue; > > seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], > > - (u64)memcg_page_state(memcg, i) * PAGE_SIZE); > > + (u64)memcg_page_state(memcg, memcg1_stats[i]) * > > + PAGE_SIZE); > > It seems like I made the above very subtle in 8de7ecc6483b and > Johannes missed this subtlety in 42a300353577 (and I missed it in the > review). > > > } > > > > for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) > > seq_printf(m, "total_%s %llu\n", memcg1_event_names[i], > > - (u64)memcg_events(memcg, i)); > > + (u64)memcg_events(memcg, memcg1_events[i])); > > > > for (i = 0; i < NR_LRU_LISTS; i++) > > seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], > > -- > > 1.8.3.1 > > > > Reviewed-by: Shakeel Butt <shakeelb@google.com>
On Wed, Jul 3, 2019 at 11:50 AM Shakeel Butt <shakeelb@google.com> wrote: > > +Johannes Weiner > > On Tue, Jul 2, 2019 at 6:23 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > > > When we calculate total statistics for memcg1_stats and memcg1_events, we > > use the the index 'i' in the for loop as the events index. > > Actually we should use memcg1_stats[i] and memcg1_events[i] as the > > events index. > > > > Fixes: 8de7ecc6483b ("memcg: reduce memcg tree traversals for stats collection") > > Actually it fixes 42a300353577 ("mm: memcontrol: fix recursive > statistics correctness & scalabilty"). > Hi Shakeel, In 8de7ecc6483b, this code was changed from memcg_page_state(mi, memcg1_stats[i]) to acc.stat[i]. - for_each_mem_cgroup_tree(mi, memcg) - val += memcg_page_state(mi, memcg1_stats[i]) * - PAGE_SIZE; - seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], val); + seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], + (u64)acc.stat[i] * PAGE_SIZE); In 42a300353577, this code was changed from acc.vmstats[i] to memcg_events(memcg, i). - (u64)acc.vmstats[i] * PAGE_SIZE); + (u64)memcg_page_state(memcg, i) * PAGE_SIZE); So seems this issue was introduced in 8de7ecc6483b, isn't it ? > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > Cc: Shakeel Butt <shakeelb@google.com> > > Cc: Michal Hocko <mhocko@suse.com> > > Cc: Yafang Shao <shaoyafang@didiglobal.com> > > --- > > mm/memcontrol.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 3ee806b..2ad94d0 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -3528,12 +3528,13 @@ static int memcg_stat_show(struct seq_file *m, void *v) > > if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) > > continue; > > seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], > > - (u64)memcg_page_state(memcg, i) * PAGE_SIZE); > > + (u64)memcg_page_state(memcg, memcg1_stats[i]) * > > + PAGE_SIZE); > > It seems like I made the above very subtle in 8de7ecc6483b and > Johannes missed this subtlety in 42a300353577 (and I missed it in the > review). > > > } > > > > for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) > > seq_printf(m, "total_%s %llu\n", memcg1_event_names[i], > > - (u64)memcg_events(memcg, i)); > > + (u64)memcg_events(memcg, memcg1_events[i])); > > > > for (i = 0; i < NR_LRU_LISTS; i++) > > seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], > > -- > > 1.8.3.1 > > > > Reviewed-by: Shakeel Butt <shakeelb@google.com>
On Tue, Jul 2, 2019 at 9:28 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > On Wed, Jul 3, 2019 at 11:50 AM Shakeel Butt <shakeelb@google.com> wrote: > > > > +Johannes Weiner > > > > On Tue, Jul 2, 2019 at 6:23 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > > > > > When we calculate total statistics for memcg1_stats and memcg1_events, we > > > use the the index 'i' in the for loop as the events index. > > > Actually we should use memcg1_stats[i] and memcg1_events[i] as the > > > events index. > > > > > > Fixes: 8de7ecc6483b ("memcg: reduce memcg tree traversals for stats collection") > > > > Actually it fixes 42a300353577 ("mm: memcontrol: fix recursive > > statistics correctness & scalabilty"). > > > > Hi Shakeel, > > In 8de7ecc6483b, this code was changed from memcg_page_state(mi, > memcg1_stats[i]) to acc.stat[i]. > > - for_each_mem_cgroup_tree(mi, memcg) > - val += memcg_page_state(mi, memcg1_stats[i]) * > - PAGE_SIZE; > - seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], val); > + seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], > + (u64)acc.stat[i] * PAGE_SIZE); > > In 42a300353577, this code was changed from acc.vmstats[i] to > memcg_events(memcg, i). > - (u64)acc.vmstats[i] * PAGE_SIZE); > + (u64)memcg_page_state(memcg, i) * PAGE_SIZE); > > So seems this issue was introduced in 8de7ecc6483b, isn't it ? > > That's the reason I said 8de7ecc6483b made it subtle but not wrong. Check accumulate_memcg_tree() in 8de7ecc6483b, the memcg_page_state() and memcg_events() are called with correct index but saved at 'i' index in acc array. > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > > Cc: Shakeel Butt <shakeelb@google.com> > > > Cc: Michal Hocko <mhocko@suse.com> > > > Cc: Yafang Shao <shaoyafang@didiglobal.com> > > > --- > > > mm/memcontrol.c | 5 +++-- > > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > index 3ee806b..2ad94d0 100644 > > > --- a/mm/memcontrol.c > > > +++ b/mm/memcontrol.c > > > @@ -3528,12 +3528,13 @@ static int memcg_stat_show(struct seq_file *m, void *v) > > > if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) > > > continue; > > > seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], > > > - (u64)memcg_page_state(memcg, i) * PAGE_SIZE); > > > + (u64)memcg_page_state(memcg, memcg1_stats[i]) * > > > + PAGE_SIZE); > > > > It seems like I made the above very subtle in 8de7ecc6483b and > > Johannes missed this subtlety in 42a300353577 (and I missed it in the > > review). > > > > > } > > > > > > for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) > > > seq_printf(m, "total_%s %llu\n", memcg1_event_names[i], > > > - (u64)memcg_events(memcg, i)); > > > + (u64)memcg_events(memcg, memcg1_events[i])); > > > > > > for (i = 0; i < NR_LRU_LISTS; i++) > > > seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], > > > -- > > > 1.8.3.1 > > > > > > > Reviewed-by: Shakeel Butt <shakeelb@google.com>
On Wed, Jul 3, 2019 at 1:17 PM Shakeel Butt <shakeelb@google.com> wrote: > > On Tue, Jul 2, 2019 at 9:28 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > > > On Wed, Jul 3, 2019 at 11:50 AM Shakeel Butt <shakeelb@google.com> wrote: > > > > > > +Johannes Weiner > > > > > > On Tue, Jul 2, 2019 at 6:23 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > > > > > > > When we calculate total statistics for memcg1_stats and memcg1_events, we > > > > use the the index 'i' in the for loop as the events index. > > > > Actually we should use memcg1_stats[i] and memcg1_events[i] as the > > > > events index. > > > > > > > > Fixes: 8de7ecc6483b ("memcg: reduce memcg tree traversals for stats collection") > > > > > > Actually it fixes 42a300353577 ("mm: memcontrol: fix recursive > > > statistics correctness & scalabilty"). > > > > > > > Hi Shakeel, > > > > In 8de7ecc6483b, this code was changed from memcg_page_state(mi, > > memcg1_stats[i]) to acc.stat[i]. > > > > - for_each_mem_cgroup_tree(mi, memcg) > > - val += memcg_page_state(mi, memcg1_stats[i]) * > > - PAGE_SIZE; > > - seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], val); > > + seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], > > + (u64)acc.stat[i] * PAGE_SIZE); > > > > In 42a300353577, this code was changed from acc.vmstats[i] to > > memcg_events(memcg, i). > > - (u64)acc.vmstats[i] * PAGE_SIZE); > > + (u64)memcg_page_state(memcg, i) * PAGE_SIZE); > > > > So seems this issue was introduced in 8de7ecc6483b, isn't it ? > > > > > > That's the reason I said 8de7ecc6483b made it subtle but not wrong. > Check accumulate_memcg_tree() in 8de7ecc6483b, the memcg_page_state() > and memcg_events() are called with correct index but saved at 'i' > index in acc array. > Got it. Thanks for your explanation and review. Thanks Yafang > > > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > > > Cc: Shakeel Butt <shakeelb@google.com> > > > > Cc: Michal Hocko <mhocko@suse.com> > > > > Cc: Yafang Shao <shaoyafang@didiglobal.com> > > > > --- > > > > mm/memcontrol.c | 5 +++-- > > > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > > index 3ee806b..2ad94d0 100644 > > > > --- a/mm/memcontrol.c > > > > +++ b/mm/memcontrol.c > > > > @@ -3528,12 +3528,13 @@ static int memcg_stat_show(struct seq_file *m, void *v) > > > > if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) > > > > continue; > > > > seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], > > > > - (u64)memcg_page_state(memcg, i) * PAGE_SIZE); > > > > + (u64)memcg_page_state(memcg, memcg1_stats[i]) * > > > > + PAGE_SIZE); > > > > > > It seems like I made the above very subtle in 8de7ecc6483b and > > > Johannes missed this subtlety in 42a300353577 (and I missed it in the > > > review). > > > > > > > } > > > > > > > > for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) > > > > seq_printf(m, "total_%s %llu\n", memcg1_event_names[i], > > > > - (u64)memcg_events(memcg, i)); > > > > + (u64)memcg_events(memcg, memcg1_events[i])); > > > > > > > > for (i = 0; i < NR_LRU_LISTS; i++) > > > > seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], > > > > -- > > > > 1.8.3.1 > > > > > > > > > > Reviewed-by: Shakeel Butt <shakeelb@google.com>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3ee806b..2ad94d0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3528,12 +3528,13 @@ static int memcg_stat_show(struct seq_file *m, void *v) if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) continue; seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], - (u64)memcg_page_state(memcg, i) * PAGE_SIZE); + (u64)memcg_page_state(memcg, memcg1_stats[i]) * + PAGE_SIZE); } for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) seq_printf(m, "total_%s %llu\n", memcg1_event_names[i], - (u64)memcg_events(memcg, i)); + (u64)memcg_events(memcg, memcg1_events[i])); for (i = 0; i < NR_LRU_LISTS; i++) seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i],
When we calculate total statistics for memcg1_stats and memcg1_events, we use the the index 'i' in the for loop as the events index. Actually we should use memcg1_stats[i] and memcg1_events[i] as the events index. Fixes: 8de7ecc6483b ("memcg: reduce memcg tree traversals for stats collection") Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Yafang Shao <shaoyafang@didiglobal.com> --- mm/memcontrol.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)