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authorJohannes Weiner <hannes@cmpxchg.org>2015-06-10 21:14:54 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-06-11 02:43:43 +0300
commitf371763a79d5212c2cb216b46fa8af46ba56cee3 (patch)
tree05901da392e1cd5b2c837e6709c7d262a5012ae9 /mm/memcontrol.c
parent5129e87cb81996d4d7e8f5a86b5355c5f2d0383b (diff)
downloadlinux-f371763a79d5212c2cb216b46fa8af46ba56cee3.tar.xz
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 <hannes@cmpxchg.org> Reported-by: Clark Williams <williams@redhat.com> Cc: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r--mm/memcontrol.c4
1 files changed, 1 insertions, 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);
}