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Date: Sun, 02 Nov 2014 08:31:09 +0100 From: Mike Galbraith <umgwanakikbuti@...il.com> To: Steven Rostedt <rostedt@...dmis.org> Cc: LKML <linux-kernel@...r.kernel.org>, linux-rt-users <linux-rt-users@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>, Carsten Emde <C.Emde@...dl.org>, John Kacur <jkacur@...hat.com>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Clark Williams <williams@...hat.com> Subject: 3.14.23-rt20 - mm,memcg: make refill_stock()/consume_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 <nyushchenko@....rtsoft.ru> Signed-off-by: Mike Galbraith <umgwanakikbuti@...il.com> --- mm/memcontrol.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2438,16 +2438,18 @@ static bool consume_stock(struct mem_cgr { struct memcg_stock_pcp *stock; bool ret = true; + int cpu; if (nr_pages > CHARGE_BATCH) return false; - stock = &get_cpu_var(memcg_stock); + cpu = get_cpu_light(); + stock = &per_cpu(memcg_stock, cpu); if (memcg == stock->cached && stock->nr_pages >= nr_pages) stock->nr_pages -= nr_pages; else /* need to call res_counter_charge */ ret = false; - put_cpu_var(memcg_stock); + put_cpu_light(); return ret; } @@ -2497,14 +2499,17 @@ static void __init memcg_stock_init(void */ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) { - struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock); + struct memcg_stock_pcp *stock; + int cpu = get_cpu_light(); + + stock = &per_cpu(memcg_stock, cpu); if (stock->cached != memcg) { /* reset if necessary */ drain_stock(stock); stock->cached = memcg; } stock->nr_pages += nr_pages; - put_cpu_var(memcg_stock); + put_cpu_light(); } /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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