From: Andrew Morton <akpm@linux-foundation.org>
To: Andi Kleen <andi.kleen@intel.com>
Cc: Feng Tang <feng.tang@intel.com>, Qian Cai <cai@lca.pw>,
Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
Christoph Lameter <cl@linux.com>,
kernel test robot <rong.a.chen@intel.com>,
Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Matthew Wilcox <willy@infradead.org>,
Mel Gorman <mgorman@suse.de>, Kees Cook <keescook@chromium.org>,
Luis Chamberlain <mcgrof@kernel.org>,
Iurii Zaikin <yzaikin@google.com>,
tim.c.chen@intel.com, dave.hansen@intel.com,
ying.huang@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, lkp@lists.01.org
Subject: Re: [mm] 4e2c82a409: ltp.overcommit_memory01.fail
Date: Mon, 6 Jul 2020 16:42:20 -0700 [thread overview]
Message-ID: <20200706164220.cc73e53c7f1b285910c82807@linux-foundation.org> (raw)
In-Reply-To: <20200706133434.GA3483883@tassilo.jf.intel.com>
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
next prev parent reply other threads:[~2020-07-06 23:42 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-21 7:36 [PATCH v5 0/3] make vm_committed_as_batch aware of vm overcommit policy Feng Tang
2020-06-21 7:36 ` [PATCH v5 1/3] proc/meminfo: avoid open coded reading of vm_committed_as Feng Tang
2020-06-21 7:36 ` [PATCH v5 2/3] mm/util.c: make vm_memory_committed() more accurate Feng Tang
2020-06-21 7:36 ` [PATCH v5 3/3] mm: adjust vm_committed_as_batch according to vm overcommit policy Feng Tang
2020-06-22 13:25 ` [mm] 4e2c82a409: will-it-scale.per_process_ops 1894.6% improvement kernel test robot
2020-07-02 6:32 ` [mm] 4e2c82a409: ltp.overcommit_memory01.fail kernel test robot
2020-07-02 7:12 ` Feng Tang
2020-07-05 3:20 ` Qian Cai
2020-07-05 4:44 ` Feng Tang
2020-07-05 12:15 ` Qian Cai
2020-07-05 12:58 ` Feng Tang
[not found] ` <20200705155232.GA608@lca.pw>
2020-07-06 1:43 ` Feng Tang
[not found] ` <20200706023614.GA1231@lca.pw>
2020-07-06 13:24 ` Feng Tang
2020-07-06 13:34 ` Andi Kleen
2020-07-06 23:42 ` Andrew Morton [this message]
2020-07-07 2:38 ` Feng Tang
2020-07-07 4:00 ` Huang, Ying
2020-07-07 5:41 ` Feng Tang
2020-07-09 4:55 ` Feng Tang
2020-07-09 13:40 ` Qian Cai
2020-07-09 14:15 ` Feng Tang
2020-07-10 1:38 ` Feng Tang
2020-07-07 1:06 ` Dennis Zhou
2020-07-07 3:24 ` Feng Tang
2020-07-07 10:28 ` Michal Hocko
2020-06-24 9:45 ` [PATCH v5 0/3] make vm_committed_as_batch aware of vm overcommit policy Michal Hocko
[not found] <AF8CFC10-7655-4664-974D-3632793B0710@lca.pw>
2020-07-07 12:06 ` [mm] 4e2c82a409: ltp.overcommit_memory01.fail Michal Hocko
[not found] ` <20200707130436.GA992@lca.pw>
2020-07-07 13:56 ` Michal Hocko
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