Johannes, We are seeing a panic in the latest RT kernel (4.0.4-rt1) where a VM_BUG_ON(!irqs_disabled()) in mm/memcontrol.c fires. This is because on an RT kernel, rt_mutexes (which replace spinlocks) don't disable interrupts while the lock is held. I talked to Steven and he suggested that we replace the irqs_disabled() with spin_is_held(). Does this patch work for you? Clark From: Clark Williams <williams@xxxxxxxxxx> Date: Fri, 29 May 2015 10:28:55 -0500 Subject: [PATCH] mm: change irqs_disabled() to spin_is_locked() in mem_cgroup_swapout() The irqs_disabled() check in mem_cgroup_swapout() fails on the latest RT kernel because RT mutexes do not disable interrupts when held. Change the test for the lock being held to use spin_is_locked. Reported-by: Fernando Lopez-Lezcano <nando@xxxxxxxxxxxxxxxxxx> Suggested-by: Steven Rostedt <rostedt@xxxxxxxxxxx> Signed-off-by: Clark Williams <williams@xxxxxxxxxx> --- mm/memcontrol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9da0f3e9c1f3..70befa14a8ce 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5845,7 +5845,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) page_counter_uncharge(&memcg->memory, 1); /* XXX: caller holds IRQ-safe mapping->tree_lock */ - VM_BUG_ON(!irqs_disabled()); + VM_BUG_ON(!spin_is_locked(&page_mapping(page)->tree_lock)); mem_cgroup_charge_statistics(memcg, page, -1); memcg_check_events(memcg, page); -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
