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charset=us-ascii Content-Disposition: inline In-Reply-To: <20190813075707.GA17933@dhcp22.suse.cz> User-Agent: NeoMutt/20170113 (1.7.2) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 13, 2019 at 09:57:07AM +0200, Michal Hocko wrote: >On Tue 13-08-19 10:06:08, Wei Yang wrote: >> When offline a node in try_offline_node, pgdat is not released. So that >> pgdat could be reused in hotadd_new_pgdat. While we re-allocate >> pgdat->per_cpu_nodestats if this pgdat is reused. >> >> This patch prevents the memory leak by just allocate per_cpu_nodestats >> when it is a new pgdat. > >Yes this makes sense! I was slightly confused why we haven't initialized >the allocated pcp area because __alloc_percpu does GFP_KERNEL without >__GFP_ZERO but then I've just found out that the zeroying is done >regardless. A bit unexpected... > >> NOTE: This is not tested since I didn't manage to create a case to >> offline a whole node. If my analysis is not correct, please let me know. >> >> Signed-off-by: Wei Yang > >Acked-by: Michal Hocko > >Thanks! > Thanks :-) >> --- >> mm/memory_hotplug.c | 10 +++++++++- >> 1 file changed, 9 insertions(+), 1 deletion(-) >> >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index c73f09913165..efaf9e6f580a 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -933,8 +933,11 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) >> if (!pgdat) >> return NULL; >> >> + pgdat->per_cpu_nodestats = >> + alloc_percpu(struct per_cpu_nodestat); >> arch_refresh_nodedata(nid, pgdat); >> } else { >> + int cpu; >> /* >> * Reset the nr_zones, order and classzone_idx before reuse. >> * Note that kswapd will init kswapd_classzone_idx properly >> @@ -943,6 +946,12 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) >> pgdat->nr_zones = 0; >> pgdat->kswapd_order = 0; >> pgdat->kswapd_classzone_idx = 0; >> + for_each_online_cpu(cpu) { >> + struct per_cpu_nodestat *p; >> + >> + p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu); >> + memset(p, 0, sizeof(*p)); >> + } >> } >> >> /* we can use NODE_DATA(nid) from here */ >> @@ -952,7 +961,6 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) >> >> /* init node's zones as empty zones, we don't have any present pages.*/ >> free_area_init_core_hotplug(nid); >> - pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat); >> >> /* >> * The node we allocated has no zone fallback lists. For avoiding >> -- >> 2.17.1 >> > >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me