linux-kernel - Re: [PATCH 0/5] avoid divide-by-zero due to max_nr

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Message-Id: <20231020180242.64276-1-sj@kernel.org>
Date:   Fri, 20 Oct 2023 18:02:42 +0000
From:   SeongJae Park <sj@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     SeongJae Park <sj@...nel.org>, damon@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        acsjakub@...zon.de
Subject: Re: [PATCH 0/5] avoid divide-by-zero due to max_nr_accesses overflow

On Fri, 20 Oct 2023 10:30:36 -0700 Andrew Morton <akpm@...ux-foundation.org> wrote:

> On Fri, 20 Oct 2023 17:19:01 +0000 SeongJae Park <sj@...nel.org> wrote:
> 
> > On Thu, 19 Oct 2023 19:49:19 +0000 SeongJae Park <sj@...nel.org> wrote:
> > 
> > > The maximum nr_accesses of given DAMON context can be calculated by
> > > dividing the aggregation interval by the sampling interval.  Some logics
> > > in DAMON uses the maximum nr_accesses as a divisor.  Hence, the value
> > > shouldn't be zero.  Such case is avoided since DAMON avoids setting the
> > > agregation interval as samller than the sampling interval.  However,
> > > since nr_accesses is unsigned int while the intervals are unsigned long,
> > > the maximum nr_accesses could be zero while casting.
> > 
> > Actually, the issue was reported by Jakub, and I didn't add 'Reported-by:' tags
> > for him.  I sure Andrew could add that on his own, but I want to minimize
> > Andrew's load, so will send v2 of this patchset.  Andrew, please let me know if
> > that doesn't help but only increasing your load.
> 
> Editing the changelogs is far quicker than updating a patch series ;)
> 
> btw, it's now conventional to add a link to the reporter's report.  The
> new "Closes:" tag, immediately after the Reported-by:.  But it's not a
> big deal.

Surely it is.  And in this case, the report was made privately, so no available
link.  I should have mentioned this early, sorry.  Anyway, thank you for your
help, Andrew :)


Thanks,
SJ