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 A002C3419D for ; Mon, 9 Oct 2023 13:52:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="b2rxO3OP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D5EBC433C8; Mon, 9 Oct 2023 13:52:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1696859544; bh=xkBv8x1uVWv5XW3CGAbQT0MF/FyjjN+CBj/D54XZiFE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b2rxO3OP57krjrFuarHc0UQnDnIjiJpA6m+ZenYCx6LkU5VHMY63VTW01nue/f33j qVmrXCoAPlLN6BdkJMVmG2wYQ6NdMAJlyD9rSMp8P8hIU+pRNkNPXY4wlOvSl8m6cC hmC3DbJdSgDmPfVGUZsJr8k9LeCOrhlhToWNl8bs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, mhiramat@kernel.org, Zheng Yejian , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 4.19 37/91] ring-buffer: Avoid softlockup in ring_buffer_resize() Date: Mon, 9 Oct 2023 15:06:09 +0200 Message-ID: <20231009130112.816856260@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231009130111.518916887@linuxfoundation.org> References: <20231009130111.518916887@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zheng Yejian [ Upstream commit f6bd2c92488c30ef53b5bd80c52f0a7eee9d545a ] When user resize all trace ring buffer through file 'buffer_size_kb', then in ring_buffer_resize(), kernel allocates buffer pages for each cpu in a loop. If the kernel preemption model is PREEMPT_NONE and there are many cpus and there are many buffer pages to be allocated, it may not give up cpu for a long time and finally cause a softlockup. To avoid it, call cond_resched() after each cpu buffer allocation. Link: https://lore.kernel.org/linux-trace-kernel/20230906081930.3939106-1-zhengyejian1@huawei.com Cc: Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/ring_buffer.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index c8a7de7a1d635..320aa60664dc9 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1753,6 +1753,8 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, err = -ENOMEM; goto out_err; } + + cond_resched(); } get_online_cpus(); -- 2.40.1