From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 96F903899435 for ; Tue, 13 Sep 2022 10:04:14 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 96F903899435 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663063454; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=2EH03aKpJEkp19CVJKzHZvmtmBZk+9+wikk5PAhTqz8=; b=Yb03Q9p5MHe4MK+yBSLOHuc74+jCgghFvMrOC7xvy+aygaTbOMUlQQN/0Sd+t+tzAg3GVc VOvpLOV3bPVp1m6UA6NWWqrrUfMELxJf3iVzV86HkyZ8Mxr/Hj/yTZngU6DpINuGs+U3Bj UcSbIXDwElWsY/sh54Ss+q9fERF4fNM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-354-dSWPrP9HM8GadlbEt_XZPg-1; Tue, 13 Sep 2022 06:04:13 -0400 X-MC-Unique: dSWPrP9HM8GadlbEt_XZPg-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EF6F118A01AD; Tue, 13 Sep 2022 10:04:12 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.210]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E8E6B492B04; Tue, 13 Sep 2022 10:04:11 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Netto Cc: Adhemerval Zanella Netto via Libc-help , Rain Subject: Re: posix_spawn: parent can get stuck in uninterruptible sleep if child receives SIGTSTP early enough References: <2921668c-773e-465d-9480-0abb6f979bf9@www.fastmail.com> <7727e4de-a8da-1e6b-4d7c-68a132750996@linaro.org> <64917a2f-788b-4695-b799-63bbb8a4873f@www.fastmail.com> <87tu64w33v.fsf@oldenburg.str.redhat.com> <7c356365-34db-cc00-bb92-0e55e7a89118@linaro.org> Date: Tue, 13 Sep 2022 12:04:10 +0200 In-Reply-To: <7c356365-34db-cc00-bb92-0e55e7a89118@linaro.org> (Adhemerval Zanella Netto's message of "Mon, 22 Aug 2022 15:32:47 -0300") Message-ID: <877d27vbdx.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-5.0 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: * Adhemerval Zanella Netto: > On 22/08/22 15:21, Florian Weimer wrote: >> * Adhemerval Zanella Netto via Libc-help: >> >>> Right, my mistake. I understood the issue better now, although I am >>> still puzzled why SIGTSTP is only being triggered on sigprocmask (sing >>> default action is still to stop PROCESS). >> >> I think it's a maskable stop, not an unmaskable one, like SIGSTOP. > > Yeah, we do block the signal on parent (internal_signal_block_all). > >> >> This looks a vfork-specific bug that can't happen with fork. I don't >> see how to fix it in a generic fashion because we can't unblock SIGTSTP >> and launch the new process in an atomic fashion. > > We might ask for a new clone3 field to define the default signal mask on > process start (and thus omit the final sigprocmask before execve). It might already possible to fix this using io_uring. Unfortunately, I didn't attend the LPC presentation. Thanks, Florian