From: SeongJae Park <sj@kernel.org>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: SeongJae Park <sj@kernel.org>,
syzbot <syzbot+841a46899768ec7bec67@syzkaller.appspotmail.com>,
akpm@linux-foundation.org, damon@lists.linux.dev,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [damon?] divide error in damon_set_attrs
Date: Fri, 26 May 2023 18:46:35 -0700 [thread overview]
Message-ID: <20230527014635.7380-1-sj@kernel.org> (raw)
In-Reply-To: <c18dc1e9-1805-f366-9d16-30e9628ac14e@huawei.com>
Hi Kefeng,
On Sat, 27 May 2023 09:15:01 +0800 Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
[...]
> >
> > Nice and effective fix! Nevertheless, I think aggregation interval smaller
> > than sample interval is just a wrong input. How about adding the check in
> > damon_set_attrs()'s already existing attributes validation, like below?
>
> Yes, move the check into damon_set_attrs() is better
Thank you for this kind comment!
> , and it seems that
> we could move all the check into it, and drop the old_attrs check in
> damon_update_monitoring_results(), what's you option?
>
>
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index d9ef62047bf5..1647f7f1f708 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -523,12 +523,6 @@ static void damon_update_monitoring_results(struct
> damon_ctx *ctx,
> struct damon_target *t;
> struct damon_region *r;
>
> - /* if any interval is zero, simply forgive conversion */
> - if (!old_attrs->sample_interval || !old_attrs->aggr_interval ||
> - !new_attrs->sample_interval ||
> - !new_attrs->aggr_interval)
> - return;
> -
> damon_for_each_target(t, ctx)
> damon_for_each_region(r, t)
> damon_update_monitoring_result(
> @@ -551,6 +545,10 @@ int damon_set_attrs(struct damon_ctx *ctx, struct
> damon_attrs *attrs)
> return -EINVAL;
> if (attrs->min_nr_regions > attrs->max_nr_regions)
> return -EINVAL;
> + if (attrs->sample_interval > attrs->aggr_interval)
> + return -EINVAL;
> + if (!attrs->sample_interval || !attrs->aggr_interval)
> + return -EINVAL;
In my humble opinion, the validation for monitoring results and for general
monitoring could be different. For example, zero aggreation/sampling intervals
might make sense for fixed granularity working set size monitoring. Hence, I'd
prefer keeping those checks in the damon_update_monitoring_results().
Thanks,
SJ
[...]
next prev parent reply other threads:[~2023-05-27 1:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-26 11:51 [syzbot] [damon?] divide error in damon_set_attrs syzbot
2023-05-26 12:59 ` Kefeng Wang
2023-05-26 18:54 ` SeongJae Park
2023-05-26 19:35 ` SeongJae Park
2023-05-27 1:15 ` Kefeng Wang
2023-05-27 1:46 ` SeongJae Park [this message]
2023-05-27 2:02 ` Kefeng Wang
2023-05-27 2:08 ` SeongJae Park
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