102 lines
3.3 KiB
Diff
102 lines
3.3 KiB
Diff
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
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Date: Wed, 22 Nov 2017 07:31:19 -0500
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Subject: [PATCH] Revert "memcontrol: Prevent scheduling while atomic in cgroup
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code"
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.14/older/patches-4.14.6-rt7.tar.xz
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The commit "memcontrol: Prevent scheduling while atomic in cgroup code"
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fixed this issue:
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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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But commit 3e32cb2e0a12b ("mm: memcontrol: lockless page counters") replaced
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the calls to res_counter_uncharge() in drain_stock() to the lockless
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function page_counter_uncharge(). There is no more spin lock there and no
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more reason to have that local lock.
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Cc: <stable-rt@vger.kernel.org>
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Reported-by: Haiyang HY1 Tan <tanhy1@lenovo.com>
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Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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[bigeasy: That upstream commit appeared in v3.19 and the patch in
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question in v3.18.7-rt2 and v3.18 seems still to be maintained. So I
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guess that v3.18 would need the locallocks that we are about to remove
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here. I am not sure if any earlier versions have the patch
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backported.
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The stable tag here is because Haiyang reported (and debugged) a crash
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in 4.4-RT with this patch applied (which has get_cpu_light() instead
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the locallocks it gained in v4.9-RT).
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https://lkml.kernel.org/r/05AA4EC5C6EC1D48BE2CDCFF3AE0B8A637F78A15@CNMAILEX04.lenovo.com
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]
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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mm/memcontrol.c | 13 ++++++-------
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1 file changed, 6 insertions(+), 7 deletions(-)
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--- a/mm/memcontrol.c
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+++ b/mm/memcontrol.c
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@@ -1723,7 +1723,6 @@ struct memcg_stock_pcp {
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#define FLUSHING_CACHED_CHARGE 0
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};
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static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
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-static DEFINE_LOCAL_IRQ_LOCK(memcg_stock_ll);
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static DEFINE_MUTEX(percpu_charge_mutex);
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/**
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@@ -1746,7 +1745,7 @@ static bool consume_stock(struct mem_cgr
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if (nr_pages > CHARGE_BATCH)
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return ret;
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- local_lock_irqsave(memcg_stock_ll, flags);
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+ local_irq_save(flags);
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stock = this_cpu_ptr(&memcg_stock);
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if (memcg == stock->cached && stock->nr_pages >= nr_pages) {
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@@ -1754,7 +1753,7 @@ static bool consume_stock(struct mem_cgr
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ret = true;
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}
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- local_unlock_irqrestore(memcg_stock_ll, flags);
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+ local_irq_restore(flags);
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return ret;
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}
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@@ -1785,13 +1784,13 @@ static void drain_local_stock(struct wor
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* The only protection from memory hotplug vs. drain_stock races is
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* that we always operate on local CPU stock here with IRQ disabled
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*/
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- local_lock_irqsave(memcg_stock_ll, flags);
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+ local_irq_save(flags);
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stock = this_cpu_ptr(&memcg_stock);
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drain_stock(stock);
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clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
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- local_unlock_irqrestore(memcg_stock_ll, flags);
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+ local_irq_restore(flags);
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}
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/*
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@@ -1803,7 +1802,7 @@ static void refill_stock(struct mem_cgro
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struct memcg_stock_pcp *stock;
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unsigned long flags;
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- local_lock_irqsave(memcg_stock_ll, flags);
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+ local_irq_save(flags);
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stock = this_cpu_ptr(&memcg_stock);
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if (stock->cached != memcg) { /* reset if necessary */
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@@ -1815,7 +1814,7 @@ static void refill_stock(struct mem_cgro
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if (stock->nr_pages > CHARGE_BATCH)
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drain_stock(stock);
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- local_unlock_irqrestore(memcg_stock_ll, flags);
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+ local_irq_restore(flags);
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}
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/*
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