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From: SeongJae Park <sj@kernel.org>
To: SeongJae Park <sj@kernel.org>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	damon@lists.linux.dev,
	kernel-team@meta.com,
	linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 3/6] mm/damon/lru_sort: use param_ctx correctly
Date: Mon, 15 Sep 2025 20:04:59 -0700
Message-Id: <20250916030459.114166-1-sj@kernel.org>
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On Mon, 15 Sep 2025 11:43:06 -0700 SeongJae Park <sj@kernel.org> wrote:

> On Mon, 15 Sep 2025 08:05:47 -0700 Joshua Hahn <joshua.hahnjy@gmail.com> wrote:
> 
> > On Sun, 14 Sep 2025 18:58:04 -0700 SeongJae Park <sj@kernel.org> wrote:
> > 
> > > damon_lru_sort_apply_parameters() allocates a new DAMON context, stages
> > > user-specified DAMON parameters on it, and commits to running DAMON
> > > context at once, using damon_commit_ctx().  The code is, however,
> > > directly updating the monitoring attributes of the running context. This
> > > doesn't cause a real user problem but apparently this is an
> > > unintentional mistake that can cause code review confusions and future
> > > real problems.  Fix the wrong use of the parameter context.
[...]
> > So in particular, the global ctx will never have the correct attrs pre-patch,
> > since it will always be rewritten by param_ctx, which never had its attrs
> > initialized.
[...]
And it measn the monitoring attributes prameters of DAMON_LRU_SORT are not
working at all.  I think this deserves to be a hotfix.  I will send v2 of this
separately, cc-ing stable@.


Thanks,
SJ

[...]