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From: SeongJae Park <sj@kernel.org>
To: xiakaixu1987@gmail.com
Cc: sj@kernel.org,
	akpm@linux-foundation.org,
	damon@lists.linux.dev,
	linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Kaixu Xia <kaixuxia@tencent.com>
Subject: Re: [PATCH 2/2] mm/damon/vaddr: remove comparison between mm and last_mm when checking region accesses
Date: Fri, 26 Aug 2022 17:16:29 +0000
Message-Id: <20220826171629.50210-1-sj@kernel.org>
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Hi Kaixu,

On Fri, 26 Aug 2022 16:31:18 +0800 xiakaixu1987@gmail.com wrote:

> From: Kaixu Xia <kaixuxia@tencent.com>
> 
> The damon regions that belong to the same damon target have the same
> 'struct mm_struct *mm', so it's unnecessary to compare the mm and last_mm
> objects among the damon regions in one damon target when checking accesses.

There could be multiple targets, and 'damon_va_check_accesses()' calls
'__damon_va_check_accesses()' for all the targets.  However,
'damon_va_check_accesses()' doesn't note if '__damon_va_check_accesses()' is
called with a target that same to the target it was called with for the last
time.  Hence the check is necessary.

If I'm missing something, please let me know.


Thanks,
SJ

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