From f371763a79d5212c2cb216b46fa8af46ba56cee3 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Wed, 10 Jun 2015 11:14:54 -0700 Subject: [PATCH] mm: memcontrol: fix false-positive VM_BUG_ON() on -rt On -rt, the VM_BUG_ON(!irqs_disabled()) triggers inside the memcg swapout path because the spin_lock_irq(&mapping->tree_lock) in the caller doesn't actually disable the hardware interrupts - which is fine, because on -rt the tophalves run in process context and so we are still safe from preemption while updating the statistics. Remove the VM_BUG_ON() but keep the comment of what we rely on. Signed-off-by: Johannes Weiner Reported-by: Clark Williams Cc: Fernando Lopez-Lezcano Cc: Steven Rostedt Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9da23a7ec4c0..a04225d372ba 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5835,9 +5835,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) if (!mem_cgroup_is_root(memcg)) page_counter_uncharge(&memcg->memory, 1); - /* XXX: caller holds IRQ-safe mapping->tree_lock */ - VM_BUG_ON(!irqs_disabled()); - + /* Caller disabled preemption with mapping->tree_lock */ mem_cgroup_charge_statistics(memcg, page, -1); memcg_check_events(memcg, page); } -- 2.20.1