From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2904737D for ; Sat, 27 May 2023 02:19:42 +0000 (UTC) Received: from dggpemm500001.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4QSlLQ1mj8z18LhY; Sat, 27 May 2023 09:58:06 +0800 (CST) Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Sat, 27 May 2023 10:02:38 +0800 Message-ID: <81956ca8-8228-1210-c855-e652e2f263dc@huawei.com> Date: Sat, 27 May 2023 10:02:38 +0800 Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [syzbot] [damon?] divide error in damon_set_attrs Content-Language: en-US To: SeongJae Park CC: syzbot , , , , , References: <20230527014635.7380-1-sj@kernel.org> From: Kefeng Wang In-Reply-To: <20230527014635.7380-1-sj@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected On 2023/5/27 9:46, SeongJae Park wrote: > Hi Kefeng, > > On Sat, 27 May 2023 09:15:01 +0800 Kefeng Wang 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(). ok, will keep that, I check the damon_set_attrs() called by lru_sort/reclaim monitor and sysfs/dbgfs, the above changes should be ok, maybe missing something, the working set size monitoring is not public for now? > > > Thanks, > SJ > > [...]