Messages in this thread | | | Date | Mon, 6 Jul 2020 16:42:20 -0700 | From | Andrew Morton <> | Subject | Re: [mm] 4e2c82a409: ltp.overcommit_memory01.fail |
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On Mon, 6 Jul 2020 06:34:34 -0700 Andi Kleen <andi.kleen@intel.com> wrote:
> > ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); > > - if (ret == 0 && write) > > + if (ret == 0 && write) { > > + if (sysctl_overcommit_memory == OVERCOMMIT_NEVER) > > + schedule_on_each_cpu(sync_overcommit_as); > > The schedule_on_each_cpu is not atomic, so the problem could still happen > in that window. > > I think it may be ok if it eventually resolves, but certainly needs > a comment explaining it.
It sure does.
The new exported-to-everything percpu_counter_sync() should have full formal documentation as well, please.
> Can you do some stress testing toggling the > policy all the time on different CPUs and running the test on > other CPUs and see if the test fails? > > The other alternative would be to define some intermediate state > for the sysctl variable and only switch to never once the schedule_on_each_cpu > returned. But that's more complexity. > > > -Andi
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