4.9.65-rt57-rc2 stable review patch.
If anyone has any objections, please let me know.
------------------
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
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: stable-rt@xxxxxxxxxxxxxxx
Reported-by: Haiyang HY1 Tan <tanhy1@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
[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@xxxxxxxxxxxxxxxxxxxxx
]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
mm/memcontrol.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 12b94909ba7b..c04403033aec 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1698,7 +1698,6 @@ 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);
/**
@@ -1721,7 +1720,7 @@ 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) {
@@ -1729,7 +1728,7 @@ 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;
}
@@ -1756,13 +1755,13 @@ static void drain_local_stock(struct work_struct *dummy)
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);
drain_stock(stock);
clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
- local_unlock_irqrestore(memcg_stock_ll, flags);
+ local_irq_restore(flags);
}
/*
@@ -1774,7 +1773,7 @@ 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 */
@@ -1783,7 +1782,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
}
stock->nr_pages += nr_pages;
- local_unlock_irqrestore(memcg_stock_ll, flags);
+ local_irq_restore(flags);
}
/*
--
2.13.2
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