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From: SJ Park <sj@kernel.org>
To: SJ Park <sj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	stable@vger.kernel.org,
	damon@lists.linux.dev,
	linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH] mm/damon/core: handle region split failure in apply_min_nr_regions()
Date: Sat, 18 Jul 2026 10:21:46 -0700
Message-ID: <20260718172147.87900-1-sj@kernel.org>
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On Sat, 18 Jul 2026 09:37:06 -0700 SJ Park <sj@kernel.org> wrote:

> damon_apply_min_nr_regions() repeatedly split each region until its size
> becomes small enough to meet the user-defined low limit of the number of
> regions.  The loop assumes the split operation (damon_split_region_at())
> will always succeed and create the new region.  But the operation could
> silently fail for memory allocation failures, for example.  If such
> failure happens and the region was the last region, the linked
> list-based next region fetching returns invalid pointer.  As a result,
> invalid memory dereference and corruption could happen.  Fix by breaking
> the loop in the corner case.

Sashiko found a room to improve in this patch.  I will post a new revision with
the improvement.  Please don't add this to mm-new.


Thanks,
SJ

[...]