Re: [PATCH 1/3] mm: memcontrol: make per-cpu charge cache IRQ-safe for socket accounting
flat view
From: Vladimir Davydov <hidden>
Date: 2016-09-19 15:35:55
Also in:
cgroups, lkml, netdev
On Wed, Sep 14, 2016 at 03:48:44PM -0400, Johannes Weiner wrote:
From: Johannes Weiner <redacted>
During cgroup2 rollout into production, we started encountering css
refcount underflows and css access crashes in the memory controller.
Splitting the heavily shared css reference counter into logical users
narrowed the imbalance down to the cgroup2 socket memory accounting.
The problem turns out to be the per-cpu charge cache. Cgroup1 had a
separate socket counter, but the new cgroup2 socket accounting goes
through the common charge path that uses a shared per-cpu cache for
all memory that is being tracked. Those caches are safe against
scheduling preemption, but not against interrupts - such as the newly
added packet receive path. When cache draining is interrupted by
network RX taking pages out of the cache, the resuming drain operation
will put references of in-use pages, thus causing the imbalance.
Disable IRQs during all per-cpu charge cache operations.
Fixes: f7e1cb6ec51b ("mm: memcontrol: account socket memory in unified hierarchy memory controller")
Cc: <redacted> # 4.5+
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>Acked-by: Vladimir Davydov <redacted> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>