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t=1685152013; bh=W83RVanuHQE7ZbTs/GmwjsxwIO+ZLerImcVp8bovX8k=; h=From:To:Cc:Subject:Date:In-Reply-To:From; b=td9OaHbgDQ5nnasGQrsSvKwMyKx6sEmAxp+plDOsq7zQZzBbreQOUMMzXv5XVfXwc e/PIzGGrITwnHs89p1w2t6rispHCcB/FH/NfF8MowZmFtOdNPQTRnYsQMQhaAIkIdH JceIpOQKsq2mdOH1nI5l9J+owRO9RR6hbsaD6EJHqqsZhwGKjBTrSA8jMA7DiYX/OF hc8aPHvZgef2WGPRoXpxcy56Sa+J2o7A6vToj/W658E7dlSlG67nMwSiKx44TdO2t4 KG5JGXG0psbKb7I9wrCuDtIwcKEBxb15b6Z5SZKhHFgDsnAb7WRdiMc7Sr587B8ReC /jo/9C7zEf3OA== From: SeongJae Park To: Kefeng Wang Cc: SeongJae Park , syzbot , 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 Message-Id: <20230527014635.7380-1-sj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: X-Stat-Signature: 4uhxnee4d18b7ruigjfqax6egt5phsut X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 884B818000A X-Rspam-User: X-HE-Tag: 1685152014-101972 X-HE-Meta: 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 IpZ4UpIx 55M+/uMqv+STDFWEAo5roDoYconCvOh7c+fYAEKwjv4y6WgsW5t1SV1oNWQVW3TMGQCDC0GwPzMqKyKv72Gy+y07tr+ozN2u4v/Qwrt9P2eVHQfg7c0w2eGSVxtaMvPXLdk9Lr3G9077aSDNkgD/Powvyye6FAxQ+PxyM4vf7o8HWxjJTZjt+RGlg5FzgxDLHfhrXySKp4B4ZGL05gAfLJLeaJ3mMMkn3GbBYq83/OB4DagbmEi+QRzVvn/iz/87tAF51EiyLrMLa3vIbOZkz+5D99Q4u5U9I5PEzITsVWGLhbwIB9gTofXymi1uXC2n/D/+CVFOmWqQlD4oSjGAnXxCqqq8+Eo8IjLrGQAt+jb7MbSWXpzth5jTxWcH7isHSJP2g38PTTgm9rx0zxxkc33BR3JN+qwV8JScOqL5ArzBjdPxgNkEFnXGG+iw4w6cp7lGp X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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(). Thanks, SJ [...]