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 6207621504F; Thu, 12 Dec 2024 15:21:05 +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=1734016865; cv=none; b=Qp4obbRr0eG3WdFPwt4N8Z7e5/MhmDaszqQPjf7xgPFIZcZ+UAS9KibZVJldjZKATfJSCWSaa3wZBg/zKkh50n8zygtR4J5EzEyQGRuzXv0jUrj29/ZUxceSYzBxeIInkYDj0DVwdJSKfuf++NnlXCu1nwrIjLFpJfKH2Kbd0D0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734016865; c=relaxed/simple; bh=Jb7PuwLpVwuVk6oM7htss90ZrQ6Q8jz66p/bK/put0Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=scOEhPIxtKwiPzn7srDjK2x0EA8SvvMNglBdb95OxqhW4ovJqt1otkpOJTdHKlmEcLrWf4WUf93hBdgLkSFr9AjdW69959O7RxXUHO/4/ajWikUJS074/ntVbKcltGQctuC4Ehn2xxYE+hZzwBFP/XrmYkv9GJkJsylCDrnOgf0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=E3T/dtvL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="E3T/dtvL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DB42C4CEE8; Thu, 12 Dec 2024 15:21:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734016865; bh=Jb7PuwLpVwuVk6oM7htss90ZrQ6Q8jz66p/bK/put0Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E3T/dtvL2VKfDOaCrBIXZftre5x+CwMWSeqweBjws2co9Js/2BUp5MczB05t8hKmI IhKvXetOT1/O8NnB/8EX8ugxAusiJ35usVBFgXJG4GXM0xue5VZ8b1z0P6eIB9O5hi 2ZQrvgHjhFcih4QQdlBrxYEXiwWc4GNXzNGvcIBI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Denis Nikitin , Levi Yun , Christoph Hellwig , Sasha Levin Subject: [PATCH 6.12 318/466] dma-debug: fix a possible deadlock on radix_lock Date: Thu, 12 Dec 2024 15:58:07 +0100 Message-ID: <20241212144319.360065363@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241212144306.641051666@linuxfoundation.org> References: <20241212144306.641051666@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ 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 d570535342cb7..f6f0387761d05 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -1052,9 +1052,13 @@ 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