From nobody Sat Apr 11 10:30:51 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7156B3D34B8; Fri, 6 Mar 2026 15:29:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772810963; cv=none; b=URZZnkxl5H15vbkyvnN8UCHK0ZJXmuOA54Gb83vXz1+0k56Y0dkBi9i1EVmlw+FNFdP+vMJWlt2zhm4QQhsyHrWUY1yS6KKBAOa397Ru1kdPMMNIuROvc9eYnBYAwp4QP8LDZdY9+E9cFwoZ2I1EB+r1GaYveNcthw6dVz/ILkc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772810963; c=relaxed/simple; bh=nkxfWGkCfA0dtqbKfL4Ap5CeLN1/sVBbqbCyhGOAcDM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NnXr3l1MPHcDHwg2ocjfwee3sd1cZdbgEIjtCIefuMbaqnji90Os41k3bvMBq7lk779KQm4EY5QDAOsiCnkn6TCBA+VHVmddloa5WX6uSB+5/mqhlIu/aAMVjoQr3gN+K3PzIlyGdtSEMosvY+WpEu3bcIFa0cy/lR42KnPrsd4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aTwBZS3Y; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aTwBZS3Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BE2DC2BCFC; Fri, 6 Mar 2026 15:29:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772810963; bh=nkxfWGkCfA0dtqbKfL4Ap5CeLN1/sVBbqbCyhGOAcDM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aTwBZS3Ywjwpqlqnr8nhk08L75SfMhDHB4WzT16M7NuYTrQJIlaUTKZfBDOiS+pw2 fDwtv8mmP2D7r1Gou5jHf2qSpNnywfOIrhc+qV39j/smT78jJmZ5GP6JN2OkvvMg9a MhSVsWx2x8lXbnKH1yactJ5jKHF9JPCTBAEvbbo/N2soBg4JMToN8dfzXqbfyS+uhb K1gOBXizUYdI+3uoXPA82y0eZ/a5vuXls/fj4YeHucWcJ+4R9emUb3uj3OleMaZnZw lHxNbETjbsa6RDapvwxLwIi3sqOwV/+ItxDiYIETwvmssFOvlRCvzWdJorGaMh4PSX K714SKVWryJOA== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 05/10] mm/damon/core: add damon_merge_two_regions() debug_sanity check Date: Fri, 6 Mar 2026 07:29:08 -0800 Message-ID: <20260306152914.86303-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260306152914.86303-1-sj@kernel.org> References: <20260306152914.86303-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A data corruption could cause damon_merge_two_regions() creating zero length DAMON regions. Add a sanity check for that under CONFIG_DAMON_DEBUG_SANITY. Signed-off-by: SeongJae Park --- mm/damon/core.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 2b5aed89d449d..8a3738a17cdd9 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2473,6 +2473,21 @@ static void kdamond_apply_schemes(struct damon_ctx *= c) mutex_unlock(&c->walk_control_lock); } =20 +#ifdef CONFIG_DAMON_DEBUG_SANITY +static void damon_verify_merge_two_regions( + struct damon_region *l, struct damon_region *r) +{ + /* damon_merge_two_regions() may created incorrect left region */ + WARN_ONCE(l->ar.start >=3D l->ar.end, "l: %lu-%lu, r: %lu-%lu\n", + l->ar.start, l->ar.end, r->ar.start, r->ar.end); +} +#else +static void damon_verify_merge_two_regions( + struct damon_region *l, struct damon_region *r) +{ +} +#endif + /* * Merge two adjacent regions into one region */ @@ -2486,6 +2501,7 @@ static void damon_merge_two_regions(struct damon_targ= et *t, l->nr_accesses_bp =3D l->nr_accesses * 10000; l->age =3D (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r); l->ar.end =3D r->ar.end; + damon_verify_merge_two_regions(l, r); damon_destroy_region(r, t); } =20 --=20 2.47.3