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Subject[patch] mm: memcontrol: uncharge pages on swapout fix
Date
Vladimir notes:

> > + local_irq_disable();
> > + mem_cgroup_charge_statistics(memcg, page, -1);
> > + memcg_check_events(memcg, page);
> > + local_irq_enable();
>
> AFAICT mem_cgroup_swapout() is called under mapping->tree_lock with irqs
> disabled, so we should use irq_save/restore here.

Simply remove the irq-disabling altogether and rely on the caller
holding the mapping->tree_lock for now.

Reported-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
---
mm/memcontrol.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

For "mm: memcontrol: uncharge pages on swapout" in -mm.

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ae9b630e928b..09fece0eb9f1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5777,10 +5777,11 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
if (!mem_cgroup_is_root(memcg))
page_counter_uncharge(&memcg->memory, 1);

- local_irq_disable();
+ /* XXX: caller holds IRQ-safe mapping->tree_lock */
+ VM_BUG_ON(!irqs_disabled());
+
mem_cgroup_charge_statistics(memcg, page, -1);
memcg_check_events(memcg, page);
- local_irq_enable();
}

/**
--
2.1.2


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