From 1699ccd1d0ee9ba1769ac5845a52c53844a43e26 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Wed, 22 Nov 2017 07:31:19 -0500 Subject: [PATCH 405/418] Revert "memcontrol: Prevent scheduling while atomic in cgroup code" The commit "memcontrol: Prevent scheduling while atomic in cgroup code" fixed this issue: refill_stock() get_cpu_var() drain_stock() res_counter_uncharge() res_counter_uncharge_until() spin_lock() <== boom But commit 3e32cb2e0a12b ("mm: memcontrol: lockless page counters") replaced the calls to res_counter_uncharge() in drain_stock() to the lockless function page_counter_uncharge(). There is no more spin lock there and no more reason to have that local lock. Cc: Reported-by: Haiyang HY1 Tan Signed-off-by: Steven Rostedt (VMware) [bigeasy: That upstream commit appeared in v3.19 and the patch in question in v3.18.7-rt2 and v3.18 seems still to be maintained. So I guess that v3.18 would need the locallocks that we are about to remove here. I am not sure if any earlier versions have the patch backported. The stable tag here is because Haiyang reported (and debugged) a crash in 4.4-RT with this patch applied (which has get_cpu_light() instead the locallocks it gained in v4.9-RT). https://lkml.kernel.org/r/05AA4EC5C6EC1D48BE2CDCFF3AE0B8A637F78A15@CNMAILEX04.lenovo.com ] Signed-off-by: Sebastian Andrzej Siewior --- mm/memcontrol.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index bb9562903d84..9458de860e41 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1723,7 +1723,6 @@ struct memcg_stock_pcp { #define FLUSHING_CACHED_CHARGE 0 }; static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock); -static DEFINE_LOCAL_IRQ_LOCK(memcg_stock_ll); static DEFINE_MUTEX(percpu_charge_mutex); /** @@ -1746,7 +1745,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) if (nr_pages > CHARGE_BATCH) return ret; - local_lock_irqsave(memcg_stock_ll, flags); + local_irq_save(flags); stock = this_cpu_ptr(&memcg_stock); if (memcg == stock->cached && stock->nr_pages >= nr_pages) { @@ -1754,7 +1753,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) ret = true; } - local_unlock_irqrestore(memcg_stock_ll, flags); + local_irq_restore(flags); return ret; } @@ -1785,13 +1784,13 @@ static void drain_local_stock(struct work_struct *dummy) * The only protection from memory hotplug vs. drain_stock races is * that we always operate on local CPU stock here with IRQ disabled */ - local_lock_irqsave(memcg_stock_ll, flags); + local_irq_save(flags); stock = this_cpu_ptr(&memcg_stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); - local_unlock_irqrestore(memcg_stock_ll, flags); + local_irq_restore(flags); } /* @@ -1803,7 +1802,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) struct memcg_stock_pcp *stock; unsigned long flags; - local_lock_irqsave(memcg_stock_ll, flags); + local_irq_save(flags); stock = this_cpu_ptr(&memcg_stock); if (stock->cached != memcg) { /* reset if necessary */ @@ -1815,7 +1814,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) if (stock->nr_pages > CHARGE_BATCH) drain_stock(stock); - local_unlock_irqrestore(memcg_stock_ll, flags); + local_irq_restore(flags); } /* -- 2.17.1