From: SeongJae Park <sj@kernel.org>
To: Dan Carpenter <dan.carpenter@linaro.org>
Cc: SeongJae Park <sj@kernel.org>,
oe-kbuild@lists.linux.dev, lkp@intel.com,
oe-kbuild-all@lists.linux.dev, damon@lists.linux.dev
Subject: Re: [sj:damon/next 32/42] mm/damon/core.c:1150 damos_set_effective_quota() error: uninitialized symbol 'esz'.
Date: Wed, 22 Nov 2023 18:50:49 +0000 [thread overview]
Message-ID: <20231122185049.102436-1-sj@kernel.org> (raw)
In-Reply-To: <aa9343f1-b0f9-4452-82e9-d63192ecbcd7@suswa.mountain>
On Wed, 22 Nov 2023 04:13:36 -0500 Dan Carpenter <dan.carpenter@linaro.org> wrote:
> On Tue, Nov 21, 2023 at 05:36:02PM +0000, SeongJae Park wrote:
> > Hi Dan,
> >
> > On Tue, 21 Nov 2023 02:37:12 -0500 Dan Carpenter <dan.carpenter@linaro.org> wrote:
> >
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git damon/next
> > > head: 54ffd8ae08121d8cbce1874fe46970cce643a2c7
> > > commit: 28cef0e565adbb4175f12ffffce9d0680979de60 [32/42] mm/damon/core: implement goal-oriented feedback-driven quota auto-tuning
> > > config: x86_64-randconfig-161-20231121 (https://download.01.org/0day-ci/archive/20231121/202311210420.URG3QSAS-lkp@intel.com/config)
> > > compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
> > > reproduce: (https://download.01.org/0day-ci/archive/20231121/202311210420.URG3QSAS-lkp@intel.com/reproduce)
> > >
> > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > > | Reported-by: Dan Carpenter <error27@gmail.com>
> > > | Closes: https://lore.kernel.org/r/202311210420.URG3QSAS-lkp@intel.com/
> > >
> > > smatch warnings:
> > > mm/damon/core.c:1150 damos_set_effective_quota() error: uninitialized symbol 'esz'.
> >
> > Thank you for this nice report!
> >
> > However, damos_set_effective_quota() is called from damos_adjust_quota(), which
> > ensures at least one among quota->{ms,sz,get_score} is nonzero. And
> > damos_set_effective_quota() ensures quota->{ms,get_score} is non-zero at the
> > beginning of the function. Then the function sets esz anyway, for non-zero
> > quota->ms and quota->get_score.
>
> The problem is in the "non-zero quota->ms" situation. It uses an
> uninitialized value of esz to initialize esz.
>
> 28cef0e565adbb SeongJae Park 2023-10-27 @1150 esz = min(throughput * quota->ms, esz);
> ^^^ ^^^
> This is the uninitialized variable.
Ah, you're correct. I was out of mind. Thank you for this kind explanation.
I will squash below fix to the broken commit.
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1147,7 +1147,10 @@ static void damos_set_effective_quota(struct damos_quota *quota)
quota->total_charged_ns;
else
throughput = PAGE_SIZE * 1024;
- esz = min(throughput * quota->ms, esz);
+ if (quota->get_score)
+ esz = min(throughput * quota->ms, esz);
+ else
+ esz = throughput * quota->ms;
}
if (quota->sz && quota->sz < esz)
Thanks,
SJ
>
> regards,
> dan carpenter
>
prev parent reply other threads:[~2023-11-22 18:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <473b4c2e-863d-42ec-860a-bf8ec4385240@suswa.mountain>
2023-11-21 17:36 ` [sj:damon/next 32/42] mm/damon/core.c:1150 damos_set_effective_quota() error: uninitialized symbol 'esz' SeongJae Park
2023-11-22 9:13 ` Dan Carpenter
2023-11-22 18:50 ` SeongJae Park [this message]
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