On Fri, 29 May 2015 14:26:14 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Fri, 29 May 2015 10:48:15 -0500 Clark Williams <williams@xxxxxxxxxx> wrote: > > > 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. > > > > ... > > > > --- 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); > > spin_is_locked() returns zero on uniprocessor builds. The results will > be unhappy. > > I suggest just deleting the check. Guess this is Johannes call. We can just #ifdef it out and that would remain the same when we finally merge PREEMPT_RT in mainline. If Johannes wants to keep the check on non-RT, here's a patch: From: Clark Williams <williams@xxxxxxxxxx> Date: Mon, 1 Jun 2015 13:10:39 -0500 Subject: [PATCH] mm: ifdef out VM_BUG_ON check on PREEMPT_RT_FULL The irqs_disabled() check in mem_cgroup_swapout() fails on the latest RT kernel because RT mutexes do not disable interrupts when held. Ifdef this check out for PREEMPT_RT_FULL. Signed-off-by: Clark Williams <williams@xxxxxxxxxx> --- mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9da0f3e9c1f3..f3fcef7713f6 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5844,8 +5844,10 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) if (!mem_cgroup_is_root(memcg)) page_counter_uncharge(&memcg->memory, 1); +#ifndef CONFIG_PREEMPT_RT_FULL /* XXX: caller holds IRQ-safe mapping->tree_lock */ VM_BUG_ON(!irqs_disabled()); +#endif 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
