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 E9F571FC8; Sat, 11 Apr 2026 21:36:43 +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=1775943404; cv=none; b=qIc0tFc4DFSD1R/eA+QFHOCGhgaonevEvFzMNMMWuM942kvjtC4QDFoMukkovULUXnFg2YSDBYyHvss1n2vpA7EbyFgz97GdBjF0cze39DGH8uYel/zyMvktThstTGk+6tE4SAqfP64+wbAfNojeUqfboDeE14XAspGfJRZr5k0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775943404; c=relaxed/simple; bh=QPyTCBOcvix0CTzcdOfzWMx07raK0kRLMFwQNf37D0Y=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=CkjMT/rYXKRXGb8+9kWWgBZPl8NOZW+qlAs3H55cAhJbdBtO+ebCXRvrCGg99lBiEgcM8mADVdvDsZBHQPGCKF+4FP5ApR5ea47YYCfwxS0/3U+IAj7kyqegrvjQzrON6KhNXgd2j8UUsjcNaC49O49XRbFW109bLPnUs8DTDgw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GG59J4Qu; 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="GG59J4Qu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 49E15C116C6; Sat, 11 Apr 2026 21:36:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775943403; bh=QPyTCBOcvix0CTzcdOfzWMx07raK0kRLMFwQNf37D0Y=; h=From:To:Cc:Subject:Date:From; b=GG59J4QuLV9E77nTCwE5A0NmaXg4XnCb9AHxSdTolltGc5w6hPwUzKtPiGUZt5ttt WeivEuzp+8KD5CUscFpoGf5ckvEThPb/gBUGdGLiMgL7Aye8xX1BMseiH/8gDjJAL7 zDy0ZiH8NTtyr8QE7NuyvRhS80hHKPE4O5h/SXmkozeit7AdSD2c9Ir1UMDe3+IDMq mHDYgkRfpYmxv+ax1TmLIuC+SVmwlGaFy+L9GchgfbxzRehhG5988aGS8l6rbOdDuG MXUj9F4V5oR8b9sDZY357POBMSypneEah9DLjST58YwC/fvkHX7Yk6IoY2TwnT6yPn hhj7jeZrblGzg== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , "# 6 . 18 . x" , Quanmin Yan , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH] mm/damon/core: disallow non-power of two min_region_sz on damon_start() Date: Sat, 11 Apr 2026 14:36:36 -0700 Message-ID: <20260411213638.77768-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Commit d8f867fa0825 ("mm/damon: add damon_ctx->min_sz_region") introduced a bug that allows unaligned DAMON region address ranges. Commit c80f46ac228b ("mm/damon/core: disallow non-power of two min_region_sz") fixed it, but only for damon_commit_ctx() use case. Still, DAMON sysfs interface can emit non-power of two min_region_sz via damon_start(). Fix the path by adding the is_power_of_2() check on damon_start(). The issue was discovered by sashiko [1]. [1] https://lore.kernel.org/20260403155530.64647-1-sj@kernel.org Fixes: d8f867fa0825 ("mm/damon: add damon_ctx->min_sz_region") Cc: # 6.18.x Signed-off-by: SeongJae Park --- mm/damon/core.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 3703f62a876b3..c107d74c77e74 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -1368,6 +1368,11 @@ int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive) int i; int err = 0; + for (i = 0; i < nr_ctxs; i++) { + if (!is_power_of_2(ctxs[i]->min_region_sz)) + return -EINVAL; + } + mutex_lock(&damon_lock); if ((exclusive && nr_running_ctxs) || (!exclusive && running_exclusive_ctxs)) { base-commit: 872b6168e577ea326324255fa8b6716a89124680 -- 2.47.3