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 4942D1B0F36; Sun, 24 Nov 2024 13:50:55 +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=1732456255; cv=none; b=gRz3qrhvwUxMFFepm3WmOU7q9jyVel24yUi5wvX9mRGtWBAhxGyGXWuRyVzhMGpl/U7rYGgkXt4ObGx6s+AqyPM8MRMRMjUBcALUSAh4zkevZWF6CnmFMkZanHbxxuIpC2EPmejbc9KfQbjvH5JjVLURCB60edNxIV+9wRnRZ18= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732456255; c=relaxed/simple; bh=pBZ5xxcEVnsY4o6Auj6hl5iczWwwi3GoOZOpbG3j0+Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fr8FCj1Jqfr+mQXLH2NdNrLfHKp2qUICNKkmktOGO2iS45AmzqUQtjcNEHXeOCLhU9sdslD++a0O861NBiGbfHUZd0U4pFL1jO0af2LseEWHMQ41eULWnnogkpmzFZ4R0RNv/yXdKe5VVHUJbdMbBkIwS6mA35+rd9x6/T6wdLQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Uph4N7ck; 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="Uph4N7ck" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33B70C4CECC; Sun, 24 Nov 2024 13:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732456255; bh=pBZ5xxcEVnsY4o6Auj6hl5iczWwwi3GoOZOpbG3j0+Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Uph4N7ckwMlQtXpDCU6cfrO+/cNuHfVxTHzF+WGRA9OohpinEq9+pnn8ByPhiCuHE x874GGZhh/9XOLlUQBKoujojbwJB8sJ2KP+RNfLWcEUgzJuzIgbyPSs2G7ULOL3mNg SbDF0F0Vyst/YCt4ovnh/BKIn5Cbbw3SVb0PzWe5Bs7KlXMCZdo3XU0jQFJwIiMS1c VH60fkL2ZBOBS4mdv7OnSc3Ocp7fISv2qxORPYpwjIkPSOQ5ACN8DZ5NyKDlJjKZKW oX2HPdE6dAUXsBGYSKiY3PWuntH3OgAVo5IPeNvIE/RqLfwq44ttiCspVAuyCIlKjU dZ3tAkuFxUl4w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Levi Yun , Denis Nikitin , Christoph Hellwig , Sasha Levin , m.szyprowski@samsung.com, iommu@lists.linux.dev Subject: [PATCH AUTOSEL 6.1 30/48] dma-debug: fix a possible deadlock on radix_lock Date: Sun, 24 Nov 2024 08:48:53 -0500 Message-ID: <20241124134950.3348099-30-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241124134950.3348099-1-sashal@kernel.org> References: <20241124134950.3348099-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.1.119 Content-Transfer-Encoding: 8bit From: Levi Yun [ Upstream commit 7543c3e3b9b88212fcd0aaf5cab5588797bdc7de ] radix_lock() shouldn't be held while holding dma_hash_entry[idx].lock otherwise, there's a possible deadlock scenario when dma debug API is called holding rq_lock(): CPU0 CPU1 CPU2 dma_free_attrs() check_unmap() add_dma_entry() __schedule() //out (A) rq_lock() get_hash_bucket() (A) dma_entry_hash check_sync() (A) radix_lock() (W) dma_entry_hash dma_entry_free() (W) radix_lock() // CPU2's one (W) rq_lock() CPU1 situation can happen when it extending radix tree and it tries to wake up kswapd via wake_all_kswapd(). CPU2 situation can happen while perf_event_task_sched_out() (i.e. dma sync operation is called while deleting perf_event using etm and etr tmc which are Arm Coresight hwtracing driver backends). To remove this possible situation, call dma_entry_free() after put_hash_bucket() in check_unmap(). Reported-by: Denis Nikitin Closes: https://lists.linaro.org/archives/list/coresight@lists.linaro.org/thread/2WMS7BBSF5OZYB63VT44U5YWLFP5HL6U/#RWM6MLQX5ANBTEQ2PRM7OXCBGCE6NPWU Signed-off-by: Levi Yun Signed-off-by: Christoph Hellwig Signed-off-by: Sasha Levin --- kernel/dma/debug.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index de02c0808fb83..3e6f2a39beb3b 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -1044,9 +1044,13 @@ static void check_unmap(struct dma_debug_entry *ref) } hash_bucket_del(entry); - dma_entry_free(entry); - put_hash_bucket(bucket, flags); + + /* + * Free the entry outside of bucket_lock to avoid ABBA deadlocks + * between that and radix_lock. + */ + dma_entry_free(entry); } static void check_for_stack(struct device *dev, -- 2.43.0