66 lines
2.1 KiB
Diff
66 lines
2.1 KiB
Diff
From: Mike Galbraith <umgwanakikbuti@gmail.com>
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Date: Sat, 21 Jun 2014 10:09:48 +0200
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Subject: memcontrol: Prevent scheduling while atomic in cgroup code
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.4/patches-4.4.1-rt5.tar.xz
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mm, memcg: make refill_stock() use get_cpu_light()
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Nikita reported the following memcg scheduling while atomic bug:
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Call Trace:
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[e22d5a90] [c0007ea8] show_stack+0x4c/0x168 (unreliable)
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[e22d5ad0] [c0618c04] __schedule_bug+0x94/0xb0
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[e22d5ae0] [c060b9ec] __schedule+0x530/0x550
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[e22d5bf0] [c060bacc] schedule+0x30/0xbc
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[e22d5c00] [c060ca24] rt_spin_lock_slowlock+0x180/0x27c
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[e22d5c70] [c00b39dc] res_counter_uncharge_until+0x40/0xc4
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[e22d5ca0] [c013ca88] drain_stock.isra.20+0x54/0x98
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[e22d5cc0] [c01402ac] __mem_cgroup_try_charge+0x2e8/0xbac
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[e22d5d70] [c01410d4] mem_cgroup_charge_common+0x3c/0x70
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[e22d5d90] [c0117284] __do_fault+0x38c/0x510
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[e22d5df0] [c011a5f4] handle_pte_fault+0x98/0x858
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[e22d5e50] [c060ed08] do_page_fault+0x42c/0x6fc
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[e22d5f40] [c000f5b4] handle_page_fault+0xc/0x80
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What happens:
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refill_stock()
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get_cpu_var()
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drain_stock()
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res_counter_uncharge()
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res_counter_uncharge_until()
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spin_lock() <== boom
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Fix it by replacing get/put_cpu_var() with get/put_cpu_light().
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Reported-by: Nikita Yushchenko <nyushchenko@dev.rtsoft.ru>
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Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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mm/memcontrol.c | 7 +++++--
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1 file changed, 5 insertions(+), 2 deletions(-)
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--- a/mm/memcontrol.c
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+++ b/mm/memcontrol.c
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@@ -1937,14 +1937,17 @@ static void drain_local_stock(struct wor
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*/
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static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
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{
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- struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock);
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+ struct memcg_stock_pcp *stock;
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+ int cpu = get_cpu_light();
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+
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+ stock = &per_cpu(memcg_stock, cpu);
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if (stock->cached != memcg) { /* reset if necessary */
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drain_stock(stock);
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stock->cached = memcg;
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}
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stock->nr_pages += nr_pages;
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- put_cpu_var(memcg_stock);
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+ put_cpu_light();
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}
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/*
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