From mboxrd@z Thu Jan 1 00:00:00 1970 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 8A2F2337BB6; Sun, 1 Mar 2026 17:43:32 +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=1772387012; cv=none; b=OXymLCL62PAd6NAMszqBf3eCl4sSMtANsvOKTxlTS+74gUq/Dw2dW8QgWAAd2yqny53kDyW4DtFS11wb1tMM2XfJY0UgB4mAcwEUz0eDomYENK+w/Ktg4T6GrtSUXmaBz1oOX/aJ8zvcpvruTGiNaWG3QxuZ1M02XRJ8OtFJA2s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772387012; c=relaxed/simple; bh=nkxfWGkCfA0dtqbKfL4Ap5CeLN1/sVBbqbCyhGOAcDM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IALWcGDTxPTDNRvAvZM/0frzQAxLrMLPgdtSUQeor7VB2rXI4eELeM5ghiY00iLZ7i4PepBNSqqbvRvN2qk96+/a85ofv6miinkvrwkWIuLFt2S1Ebp5TO12TFP033Q4PGs9YDCoT9Xz9Q0zV/zUejF81YhciNuoxj2ExJCoxjc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pa/1Hh26; 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="pa/1Hh26" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53B92C2BCAF; Sun, 1 Mar 2026 17:43:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772387012; bh=nkxfWGkCfA0dtqbKfL4Ap5CeLN1/sVBbqbCyhGOAcDM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pa/1Hh267VDif0fGECk4ZBsQQZXzXfS8+im3ufGhSbXqQAUw5hsIrfOzfy1h442s/ leZWhqr9a1qEaoiqvnQ+flJSjdWw3+l2hcccGnCWBNysvlfgxgesGRG0eztr2m27Z5 WFbIAE6/2kpFTBY+s9f0zz7IHcv67IRQ5eSBBJW+hAdlcNtb92GOzS1cyCPk0FzBbx 1TUeRYgSDmgNq8F7wegrNC4MyLjIRII4Bx2xUSOylKEm99RqJ8jyEtUx4zLNhjvq2r vD749FkEGato7zuc9wkEF98Wvaxk35fOtkn+VyN1KBJth4VY00iiizRnFXsNI5bvQu bppMvpKICqtyg== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v2 05/10] mm/damon/core: add damon_merge_two_regions() debug_sanity check Date: Sun, 1 Mar 2026 09:43:20 -0800 Message-ID: <20260301174327.76849-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260301174327.76849-1-sj@kernel.org> References: <20260301174327.76849-1-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: 8bit 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); } +#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 >= 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_target *t, l->nr_accesses_bp = l->nr_accesses * 10000; l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r); l->ar.end = r->ar.end; + damon_verify_merge_two_regions(l, r); damon_destroy_region(r, t); } -- 2.47.3