From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48B5EC433E0 for ; Fri, 26 Mar 2021 20:45:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37E5D61A24 for ; Fri, 26 Mar 2021 20:45:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230237AbhCZUo5 (ORCPT ); Fri, 26 Mar 2021 16:44:57 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:60042 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230027AbhCZUop (ORCPT ); Fri, 26 Mar 2021 16:44:45 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out01.mta.xmission.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1lPtJz-00A5f3-2Z; Fri, 26 Mar 2021 14:44:43 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=fess.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1lPtJy-0002C4-6V; Fri, 26 Mar 2021 14:44:42 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Jens Axboe Cc: io-uring@vger.kernel.org, torvalds@linux-foundation.org, metze@samba.org, oleg@redhat.com, linux-kernel@vger.kernel.org References: <20210326155128.1057078-1-axboe@kernel.dk> <20210326155128.1057078-2-axboe@kernel.dk> Date: Fri, 26 Mar 2021 15:43:43 -0500 In-Reply-To: <20210326155128.1057078-2-axboe@kernel.dk> (Jens Axboe's message of "Fri, 26 Mar 2021 09:51:14 -0600") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1lPtJy-0002C4-6V;;;mid=;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/VwxW8Az6YjAF6RN0b0XNHN+rhgD9lWjg= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH 1/7] kernel: don't call do_exit() for PF_IO_WORKER threads X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jens Axboe writes: > Right now we're never calling get_signal() from PF_IO_WORKER threads, but > in preparation for doing so, don't handle a fatal signal for them. The > workers have state they need to cleanup when exiting, and they don't do > coredumps, so just return instead of performing either a dump or calling > do_exit() on their behalf. The threads themselves will detect a fatal > signal and do proper shutdown. > > Signed-off-by: Jens Axboe > --- > kernel/signal.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/kernel/signal.c b/kernel/signal.c > index f2a1b898da29..e3e1b8fbfe8a 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -2756,6 +2756,15 @@ bool get_signal(struct ksignal *ksig) > */ > current->flags |= PF_SIGNALED; > > + /* > + * PF_IO_WORKER threads will catch and exit on fatal signals > + * themselves. They have cleanup that must be performed, so > + * we cannot call do_exit() on their behalf. coredumps also > + * do not apply to them. > + */ > + if (current->flags & PF_IO_WORKER) > + return false; > + Returning false when get_signal needs the caller to handle a signal adds a very weird and awkward special case to how get_signal returns arguments. Instead you should simply break and let get_signal return SIGKILL like any other signal that has a handler that the caller of get_signal needs to handle. Something like: > + /* > + * PF_IO_WORKER have cleanup that must be performed, > + * before calling do_exit(). > + */ > + if (current->flags & PF_IO_WORKER) > + break; As do_coredump does not call do_exit there is no reason to skip calling into the coredump handling either. And allowing it will remove yet another special case from the io worker code. > if (sig_kernel_coredump(signr)) { > if (print_fatal_signals) > print_fatal_signal(ksig->info.si_signo); Eric