From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752104AbdHAMmd (ORCPT ); Tue, 1 Aug 2017 08:42:33 -0400 Received: from mail-pg0-f52.google.com ([74.125.83.52]:36923 "EHLO mail-pg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752017AbdHAMlv (ORCPT ); Tue, 1 Aug 2017 08:41:51 -0400 Date: Tue, 1 Aug 2017 21:42:04 +0900 From: Sergey Senozhatsky To: Arnd Bergmann , Greg Kroah-Hartman Cc: Linux-Next Mailing List , Linux Kernel Mailing List , Stephen Rothwell , Sergey Senozhatsky , Sergey Senozhatsky Subject: Re: linux-next: Tree for Aug 1 Message-ID: <20170801124204.GA457@jagdpanzerIV.localdomain> References: <20170801173746.6962444d@canb.auug.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170801173746.6962444d@canb.auug.org.au> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, seems that commit 979990c6284814617 ("tty: improve tty_insert_flip_char() fast path") panics my kernel. in particular, this part @@ -26,7 +27,7 @@ static inline int tty_insert_flip_char(struct tty_port *port, *char_buf_ptr(tb, tb->used++) = ch; return 1; } - return tty_insert_flip_string_flags(port, &ch, &flag, 1); + return __tty_insert_flip_char(port, ch, flag); } I see various callstacks, but all endup in llist_del_first() -> fatal exception in interrupt -> panic() ... uart_insert_char() __tty_insert_flip_char() __tty_buffer_request_room() llist_del_first() or ... kdb_event() puts_queue() __tty_insert_flip_char() __tty_buffer_request_room() llist_del_first() to reproduce: 1) screen /dev/ttyS0 115200 2) send several chars down to /dev/ttyS0, enough to panic() the kernel. reverting that __tty_insert_flip_char(port, ch, flag) seems to work on my side. -ss