From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8162537D for ; Sat, 27 May 2023 02:09:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5480C433EF; Sat, 27 May 2023 02:09:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1685153347; bh=HN9NwkpD1iuTdQGq2w1K5FjteO+8O/u8Z419WVY0jwU=; h=From:To:Cc:Subject:Date:In-Reply-To:From; b=YYMmaGwo67YMuvAG4IqiZxvJBDzjj1lsDAT9lxqlhcLdxk4tYmTRwTqv7gDVLzWiQ f4jqOoGVEU/vaCd5z7MG8XvlRr4iuJrBhQ1/6ffwKU6mW/qPwLqrtPS/otAo3dYLyQ wLgvfXYJaV+62HBxf520xvXF3Fu+BYHAt2DfdcBChjruXxCJZ8fjdU7DBa5abQFL27 H18U1jrgQZiycmV9ZucdsYjG2P1oC5tnaJy/+ULlPqoOnCdU7i73Mdd+NwwtRDI/Gb A2Wb3/TwLatioa0XJKJF6GjC2o1zhZ89B5aBPazxNExc5iLoCsPwXib+v34lLXjyJg QLn8Z1y75EJOQ== 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 19:08:51 -0700 Message-Id: <20230527020851.7855-1-sj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <81956ca8-8228-1210-c855-e652e2f263dc@huawei.com> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: On Sat, 27 May 2023 10:02:38 +0800 Kefeng Wang wrote: > > > 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, Thank you for agreeing. > 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? You're correct. Working set size monitoring is not somewhat currently publicly exists, but only possible usage of DAMON at the moment. Thanks, SJ [...]