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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 D1D2BC28CF6 for ; Fri, 3 Aug 2018 13:39:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D8072175D for ; Fri, 3 Aug 2018 13:39:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7D8072175D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731997AbeHCPfv (ORCPT ); Fri, 3 Aug 2018 11:35:51 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:42092 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729841AbeHCPfv (ORCPT ); Fri, 3 Aug 2018 11:35:51 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 322BD40216F7; Fri, 3 Aug 2018 13:39:26 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.34.27.30]) by smtp.corp.redhat.com (Postfix) with SMTP id F009410CD79E; Fri, 3 Aug 2018 13:39:24 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 3 Aug 2018 15:39:25 +0200 (CEST) Date: Fri, 3 Aug 2018 15:39:24 +0200 From: Oleg Nesterov To: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Ivan Delalande , Al Viro , linux-fsdevel@vger.kernel.org, open list , Andy Lutomirski Subject: Re: [PATCH RESEND] exec: don't force_sigsegv processes with a pending fatal signal Message-ID: <20180803133923.GA19752@redhat.com> References: <20180731005615.GA2911@visor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Fri, 03 Aug 2018 13:39:26 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Fri, 03 Aug 2018 13:39:26 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'oleg@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/02, Dmitry Safonov wrote: > > Hi Ivan, > > 2018-07-31 1:56 GMT+01:00 Ivan Delalande : > > We were seeing unexplained segfaults in coreutils processes and other > > basic utilities that we tracked down to binfmt_elf failing to load > > segments for ld.so. Digging further, the actual problem seems to occur > > when a process gets sigkilled while it is still being loaded by the > > kernel. In our case when _do_page_fault goes for a retry it will return > > early as it first checks for fatal_signal_pending(), so load_elf_interp > > also returns with error and as a result search_binary_handler will > > force_sigsegv() which is pretty confusing as nothing actually failed > > here. > > > > Fixes: 19d860a140be ("handle suicide on late failure exits in execve() in search_binary_handler()") > > Reference: https://lkml.org/lkml/2013/2/14/5 > > Signed-off-by: Ivan Delalande > > +Cc: Oleg Nesterov > +Cc: Andy Lutomirski Thanks... and sorry, I fail to understand the problem and what/how this patch tries to fix. Hmm. After I read the next email from Dmitry it seems to me that the whole purpose of this patch is to avoid print_fatal_signal()? If yes, the changelog should clearly explain this. > > --- a/fs/exec.c > > +++ b/fs/exec.c > > @@ -1656,7 +1656,8 @@ int search_binary_handler(struct linux_binprm *bprm) > > if (retval < 0 && !bprm->mm) { > > /* we got to flush_old_exec() and failed after it */ > > read_unlock(&binfmt_lock); > > - force_sigsegv(SIGSEGV, current); > > + if (!fatal_signal_pending(current)) > > + force_sigsegv(SIGSEGV, current); I won't argue, but may be force_sigsegv() should check fatal_signal_pending() itself. setup_rt_frame() can too fail if fatal_signal_pending() by the same reason. Oleg.