On Sat, Feb 3, 2018 at 12:23 AM, Johannes Weiner <[email protected]> wrote: > After the ("a983b5ebee57 mm: memcontrol: fix excessive complexity in > memory.stat reporting"), we observed slowly upward creeping > NR_WRITEBACK counts over the course of several days, both the > per-memcg stats as well as the system counter in e.g. /proc/meminfo. > > The conversion from full per-cpu stat counts to per-cpu cached atomic > stat counts introduced an irq-unsafe RMW operation into the updates. > > Most stat updates come from process context, but one notable exception > is the NR_WRITEBACK counter. While writebacks are issued from process > context, they are retired from (soft)irq context. > > When writeback completions interrupt the RMW counter updates of new > writebacks being issued, the decs from the completions are lost. > > Since the global updates are routed through the joint lruvec API, both > the memcg counters as well as the system counters are affected. > > This patch makes the joint stat and event API irq safe. > > Fixes: a983b5ebee57 ("mm: memcontrol: fix excessive complexity in memory.stat > reporting") > Debugged-by: Tejun Heo <[email protected]> > Signed-off-by: Johannes Weiner <[email protected]>
Should this be considered for stable?
