From 60efec9d4342a3b6930882da022585c2fd6b0b2a Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Sat, 21 Jun 2014 10:09:48 +0200 Subject: [PATCH 317/365] memcontrol: Prevent scheduling while atomic in cgroup code mm, memcg: make refill_stock() use get_cpu_light() Nikita reported the following memcg scheduling while atomic bug: Call Trace: [e22d5a90] [c0007ea8] show_stack+0x4c/0x168 (unreliable) [e22d5ad0] [c0618c04] __schedule_bug+0x94/0xb0 [e22d5ae0] [c060b9ec] __schedule+0x530/0x550 [e22d5bf0] [c060bacc] schedule+0x30/0xbc [e22d5c00] [c060ca24] rt_spin_lock_slowlock+0x180/0x27c [e22d5c70] [c00b39dc] res_counter_uncharge_until+0x40/0xc4 [e22d5ca0] [c013ca88] drain_stock.isra.20+0x54/0x98 [e22d5cc0] [c01402ac] __mem_cgroup_try_charge+0x2e8/0xbac [e22d5d70] [c01410d4] mem_cgroup_charge_common+0x3c/0x70 [e22d5d90] [c0117284] __do_fault+0x38c/0x510 [e22d5df0] [c011a5f4] handle_pte_fault+0x98/0x858 [e22d5e50] [c060ed08] do_page_fault+0x42c/0x6fc [e22d5f40] [c000f5b4] handle_page_fault+0xc/0x80 What happens: refill_stock() get_cpu_var() drain_stock() res_counter_uncharge() res_counter_uncharge_until() spin_lock() <== boom Fix it by replacing get/put_cpu_var() with get/put_cpu_light(). Reported-by: Nikita Yushchenko Signed-off-by: Mike Galbraith [bigeasy: use memcg_stock_ll as a locallock since it is now IRQ-off region] Signed-off-by: Sebastian Andrzej Siewior --- mm/memcontrol.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1c39495b1677..106918b6b30b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1717,6 +1717,7 @@ 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); /** @@ -1739,7 +1740,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) if (nr_pages > CHARGE_BATCH) return ret; - local_irq_save(flags); + local_lock_irqsave(memcg_stock_ll, flags); stock = this_cpu_ptr(&memcg_stock); if (memcg == stock->cached && stock->nr_pages >= nr_pages) { @@ -1747,7 +1748,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) ret = true; } - local_irq_restore(flags); + local_unlock_irqrestore(memcg_stock_ll, flags); return ret; } @@ -1774,13 +1775,13 @@ static void drain_local_stock(struct work_struct *dummy) struct memcg_stock_pcp *stock; unsigned long flags; - local_irq_save(flags); + local_lock_irqsave(memcg_stock_ll, flags); stock = this_cpu_ptr(&memcg_stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); - local_irq_restore(flags); + local_unlock_irqrestore(memcg_stock_ll, flags); } /* @@ -1792,7 +1793,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) struct memcg_stock_pcp *stock; unsigned long flags; - local_irq_save(flags); + local_lock_irqsave(memcg_stock_ll, flags); stock = this_cpu_ptr(&memcg_stock); if (stock->cached != memcg) { /* reset if necessary */ @@ -1801,7 +1802,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) } stock->nr_pages += nr_pages; - local_irq_restore(flags); + local_unlock_irqrestore(memcg_stock_ll, flags); } /* -- 2.28.0