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imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=GG59J4Qu; spf=pass (imf07.hostedemail.com: domain of sj@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775943404; a=rsa-sha256; cv=none; b=fHx161gfmcK1Iam1h/lS2kXKIxOH9RXZ9GiVvRPh45lis+Hyvspas0nhxm6XJDRgrotwih dxZghv0lC5olosWcsBwTM12KbBR18ks1K1pbPqGoIVQxECvjDFtkXb5CtkLc6+0brf7K+o CBahAhsc0oQvIXDmBucSQlqvR7z9saY= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id D373D6015B; Sat, 11 Apr 2026 21:36:43 +0000 (UTC) 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 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7D1C440005 X-Stat-Signature: xf4z6f7roxq63gss7w6ibrc9za7frutn X-Rspam-User: X-HE-Tag: 1775943404-578284 X-HE-Meta: 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 Yx/9b1cI See5K5LDUxQmwLz6GQfYkrR6TUrg5H/9WNRiHY4f7ArN0d2mFhSBqlnR5SZ18wJJ4uy5SHORQNDyA5EsdxajaEo78SBhOgmhXOSiHJ1AV6wXV+GfT++vAEDWjL+7lp5qwFyHiJjN/KwRYXhIzNXCO+K9pHC+xSfOqvRjIDGGVt+mTiIgFjDFbXuRxsX0amgs5PLgCUvrntxhPCEGfqdygWRC3+yRgkHj9wYw/ZUg1X/r9UJ3Cta6Z1NKg16J2u4rjshl/JIoaGNZw67PUTXvmE0Q1mA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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