From: "Haitao Huang" <haitao.huang@linux.intel.com>
To: "Tejun Heo" <tj@kernel.org>
Cc: "Jarkko Sakkinen" <jarkko@kernel.org>,
dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org,
linux-sgx@vger.kernel.org, cgroups@vger.kernel.org,
"Zefan Li" <lizefan.x@bytedance.com>,
"Johannes Weiner" <hannes@cmpxchg.org>,
vipinsh@google.com, kai.huang@intel.com,
reinette.chatre@intel.com, zhiquan1.li@intel.com,
kristen@linux.intel.com
Subject: Re: [PATCH] cgroup/misc: Fix an overflow
Date: Mon, 17 Jul 2023 20:11:15 -0500 [thread overview]
Message-ID: <op.1786w1rxwjvjmi@hhuan26-mobl.amr.corp.intel.com> (raw)
In-Reply-To: <ZLWmdBfcuPUBtk1K@slm.duckdns.org>
Hi
On Mon, 17 Jul 2023 15:37:08 -0500, Tejun Heo <tj@kernel.org> wrote:
> Hello,
>
> On Mon, Jul 17, 2023 at 03:19:38PM -0500, Haitao Huang wrote:
>> Actually, we are using atomic_long_t for 'current' which is the same
>> width
>> as long defined by arch/compiler. So new_usage should be long to be
>> consistent?
>
> We can use atomic64_t, right? It's slower on 32bit machines but I think
> it'd
> be better to guarantee resource counter range than micro-optimizing
> charge
> operations. None of the current users are hot enough for this to matter
> and
> if somebody becomes that hot, the difference between atomic_t and
> atomic64_t
> isn't gonna matter that much. We'd need to batch allocations per-cpu and
> so
> on.
>
>> ditto for event counter. Only max is plain unsigned long but I think it
>> is
>> also OK as it only compared with 'current' without any arithmetic ops
>> involved.
>> Did I miss something here?
>
> I'm saying that it'd be better to make everything explicitly 64bit.
>
Thanks for the explanation. I think I got it and sent it as a separate
patch now just to be sure.
BR
Haitao
next prev parent reply other threads:[~2023-07-18 1:11 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-17 18:47 [PATCH] cgroup/misc: Fix an overflow Haitao Huang
2023-07-17 18:51 ` Tejun Heo
2023-07-17 18:55 ` Jarkko Sakkinen
2023-07-17 18:57 ` Tejun Heo
2023-07-17 19:01 ` Haitao Huang
2023-07-17 20:19 ` Haitao Huang
2023-07-17 20:37 ` Tejun Heo
2023-07-18 1:08 ` [PATCH 1/2] " Haitao Huang
2023-07-18 1:08 ` [PATCH 2/2] cgroup/misc: Change counters to be explicit 64bit types Haitao Huang
2023-07-18 22:52 ` Tejun Heo
2023-07-21 2:48 ` Haitao Huang
2023-07-21 12:02 ` [PATCH] cgroup/misc: Store atomic64_t reads to u64 Haitao Huang
2023-07-21 18:10 ` Tejun Heo
2023-07-18 1:11 ` Haitao Huang [this message]
2023-07-18 15:41 ` [PATCH] cgroup/misc: Fix an overflow Jarkko Sakkinen
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