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 96C12221D88; Thu, 12 Dec 2024 15:44:13 +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=1734018253; cv=none; b=osuXwTHddt4Tx1Spobjs6m5BhXeg0nfOTyJ/malsQRurn0W6NZezc17049Pxo1t36whGtd/QEV5JJP1VQsFWQIfvNkNIAq/uACnt+mTO2MjRJTxL11J+5piWUUT4dgh+QndP8LFoYkXAdeAb1YS+7+qTXlRe772YZWqCB4d7ltw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734018253; c=relaxed/simple; bh=fPdEj7+BuiDEB/g2Nz/UDAuFN2lNgtuiqbRYRWiW0mw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CLfrjVhWvUZxO1siGzmY92HkHLV4fP0t/UCNfCR1YIlFXV4eL2XnMq+Su73r6yXXRxRCF1D/zns8cVyd85grteoUxxtU2g7YYZAHX69VbJtIdn+qQl0hMY8CqBr9pljsDXh7REPkoXOprrGLuRgiJbKAN2qBhy2eamTH3dGw74U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JHcflnFi; 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="JHcflnFi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8CDEAC4CECE; Thu, 12 Dec 2024 15:44:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734018253; bh=fPdEj7+BuiDEB/g2Nz/UDAuFN2lNgtuiqbRYRWiW0mw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JHcflnFi2KmBaE8d8lV5kKUkj1CFU1g8BRrzAK2FGl9oUSQsOp8Ddwx5balwfIPrC xWnAe2JoR2AzNdeS5s2PpdU5lrTferfBludzfOslp/0dln27mdN0ye/o9vhH8C7fj6 YAT6lzYFEGnmbHAiJL7eu6u+lxCDRLKsdbybrAhM= 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 6.6 242/356] dma-debug: fix a possible deadlock on radix_lock Date: Thu, 12 Dec 2024 15:59:21 +0100 Message-ID: <20241212144254.173601008@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241212144244.601729511@linuxfoundation.org> References: <20241212144244.601729511@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 6.6-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 e472cc37d7de4..958d4aa77dcad 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -1051,9 +1051,13 @@ 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