From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 563734218B8; Mon, 29 Jun 2026 14:44:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782744282; cv=none; b=eFgY8X+2MMvGDrldNGgrLpYGtfs9f76r/aIFrTe5rj4ei7DUh2jlwZQwASWI6wPI87nQ4eTeqRqzRGkPuqj/Agq1Erke1hISMSOUw2mmFq+VwpTe6tEGavOi11QSjBV3+oUT/VpJNRF945wISgLGWjAh+8YbMBtpr+tsNQkv8vM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782744282; c=relaxed/simple; bh=P6RH3uPza7/i5npkvxetS0N9j86oYtT4K5gIPNjKzVg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=NyZQ4YFVfgmvSvw+tO3BDoFjEKGEfCQR6/slVYZqFdk8qqHYKwyfDnxYEZu74tOraJ2H1aQwUToGFiRHSNJwNfHu+RCzrQs4D+nc5UdR7Rto790+yj3s1EBrAdqS4zpC5dfEjjj7ulzoxyu4QphUvvrFYw9IBI7pUjLBZakOQss= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UTWtaIYq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UTWtaIYq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 899B81F000E9; Mon, 29 Jun 2026 14:44:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782744280; bh=Kd7LVRXhQqayNdQaCsVNZXfiEHFjU+l0jmqRhEGwXDg=; h=From:To:Cc:Subject:Date; b=UTWtaIYqyHgFCVTDkmRR45eFK42+RqOpV3re+1jd3KS79Sp3M4K+ZiuhLtRWwk4Qd aKQQ4R64rEd1TknW7eV9p2gTLWNyu8HNDkFcmJBgd9GAswNC+k3Abvi/CT04uPMo3W y9XPNuUtXgGJS1wAa21xEzVk74TnJF/xlocVKLgMmlJj0fPy92WQks7zyLoyi5rZKh tEytiM2ItM1+2pDQ61EVDjhU2U9R2yYj3Raz06K99THaxdRX5q/1Nc2+CgLwNzodLF 09z9r9CEQledrfb5WAADN0HHUR58VtjRIe+kaXBhy91tA07FATCiBppXicTlXYg5dx eLQGxjrn8AsOA== From: SJ Park To: Andrew Morton Cc: Zenghui Yu , SJ Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org Subject: [PATCH v3] samples/damon/mtier: fail early if address range parameters are invalid Date: Mon, 29 Jun 2026 07:44:31 -0700 Message-ID: <20260629144432.133962-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Zenghui Yu The comment on top of `struct damon_region` clearly says that For any use case, @ar should be non-zero positive size. which is now verified in damon_verify_new_region() if the kernel is built with DAMON_DEBUG_SANITY. The WARN_ONCE() can be triggered if the mtier sample module is enabled before node{0,1}_{start,end}_addr have been properly initialized, which is obviously not good. ------------[ cut here ]------------ start 0 >= end 0 WARNING: mm/damon/core.c:217 at damon_new_region+0xf4/0x118, CPU#59: bash/341468 Call trace: damon_new_region+0xf4/0x118 (P) damon_set_regions+0xfc/0x3c0 damon_sample_mtier_build_ctx+0xe8/0x3a8 damon_sample_mtier_start+0x1c/0x90 damon_sample_mtier_enable_store+0x98/0xb0 param_attr_store+0xb4/0x128 module_attr_store+0x2c/0x50 sysfs_kf_write+0x58/0x90 kernfs_fop_write_iter+0x16c/0x238 vfs_write+0x2c0/0x370 ksys_write+0x74/0x118 __arm64_sys_write+0x24/0x38 invoke_syscall+0xa8/0x118 el0_svc_common.constprop.0+0x48/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x54/0x370 el0t_64_sync_handler+0xa0/0xe8 el0t_64_sync+0x1ac/0x1b0 ---[ end trace 0000000000000000 ]--- Note that the same issue can happen if detect_node_addresses is true, and node 0 or 1 is memoryless. Fix it together by checking the validity of parameters right before damon_new_region() and fail early if they're invalid. Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering") Cc: # 6.16.x Signed-off-by: Zenghui Yu Reviewed-by: SJ Park Signed-off-by: SJ Park --- Changes from v2 - v2: https://lore.kernel.org/20260609064653.1829-1-yuzenghui@huawei.com - Collect R-b: from SJ. - Add Fixes: and Cc: stable@. - Rebase to latest mm-new. Changes from v1 - v1: https://lore.kernel.org/20260608111534.264-1-yuzenghui@huawei.com - take into account the detect_node_addresses case (Sashiko) - based on mm-new (SJ) This is a fix Cc-ing stable@. Nonetheless, because it is for a sample module, not necessarily "super hot". 7.3 should also be a reasonable target, like the other sample module fixes [1]. [1] https://lore.kernel.org/20260629132641.159851-1-sj@kernel.org samples/damon/mtier.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/samples/damon/mtier.c b/samples/damon/mtier.c index faaaaa12e6206..e567f4edd80ea 100644 --- a/samples/damon/mtier.c +++ b/samples/damon/mtier.c @@ -120,6 +120,9 @@ static struct damon_ctx *damon_sample_mtier_build_ctx(bool promote) addr.end = promote ? node1_end_addr : node0_end_addr; } + if (addr.start >= addr.end) + goto free_out; + range.start = addr.start; range.end = addr.end; base-commit: c1922f6a1a8b9a120b46051c3c5e3b81b4b75d92 -- 2.47.3