From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 DF21F305E2F for ; Thu, 25 Sep 2025 18:52:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758826325; cv=none; b=qhJc93w1xto1jjhRaQ1ZSeXZBPnmBQW6nuAHaPyrSZpfupS5pOfsUNdnioExBNXBVHu0XPo3f7lYGRuTHiSh9zg40sM9Hu7ZZtHpBLoRFaI65f6I8VknwdBx5fyQADCof60MiVGxJtx4jRjobVc8M21kUq2aDcI1l1Mxcj5NWLA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758826325; c=relaxed/simple; bh=2nl3Q+zYpLf4KxXkaeDSprSRUWy8a1j4w6Z+Pcea0d8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LbO+O4C+g14PdnidDOPPaRy6w+wxlTnkz9KoMtNHws53Rq6GhX15ZkZzNGe1GuTMxX8SJRcAcO64GsusB8aJc4Y4O+CHAj9zj9zWsM4rx5jnGOdW2djwdZUmvAqnkORwQQ5+et7XaJ/H/b2r5+ToLfHo7s7tYrr40zfPw+J/76o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=C1NgSsp6; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C1NgSsp6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758826322; 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=2nl3Q+zYpLf4KxXkaeDSprSRUWy8a1j4w6Z+Pcea0d8=; b=C1NgSsp69X2bS3fTBqVnO2PFgegAzLC9yywO5BGzKJ2j8j2KRI92ttbvGDruYtwGJF8lMn qIgLIi0666V2OdXwoVPvziryJYrUg6yt3Ral/AUFdjaBvU2AT5B1k/zqAnLMR66APxo8ER wK11Q6NzMrGfxSl/RcJy03uzxeUpXbA= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-690-bQeQQS8TMbu5oCYscIer3A-1; Thu, 25 Sep 2025 14:52:01 -0400 X-MC-Unique: bQeQQS8TMbu5oCYscIer3A-1 X-Mimecast-MFC-AGG-ID: bQeQQS8TMbu5oCYscIer3A_1758826320 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2F38A19560B5; Thu, 25 Sep 2025 18:52:00 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.44.32.16]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 48D961956095; Thu, 25 Sep 2025 18:51:56 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 25 Sep 2025 20:50:37 +0200 (CEST) Date: Thu, 25 Sep 2025 20:50:33 +0200 From: Oleg Nesterov To: Mateusz Guzik Cc: Andrew Morton , Demi Marie Obenour , Christian Brauner , Linux kernel mailing list Subject: Re: [PATCH] kernel: Prevent prctl(PR_SET_PDEATHSIG) from racing with parent process exit Message-ID: <20250925185032.GC25838@redhat.com> References: <20250913-fix-prctl-pdeathsig-race-v1-1-44e2eb426fe9@gmail.com> <20250922154819.c3049158ca006e1561ff5dcb@linux-foundation.org> <20250923120344.GA12377@redhat.com> <20250925162759.GA25838@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 3.0 on 10.30.177.17 On 09/25, Mateusz Guzik wrote: > > It struck me that this mail thread is perhaps a little rude towards > Demi, so I would like to state the reported race is legitimate and if > it was reported against come core functionality it would count as > "good spotting". Agreed, agreed. Sorry if my emails were not clear in this respect. Although let me repeat, I didn't know that people still rely on this API, but this is is almost offtopic. > > OK. I won't argue with this patch. At least the usage of tasklist_lock is well > > documented. > > > > ye.. avoiding smp_mb may be a case of "premature optimization", except > it is also simpler, so that's a really tough call. good news is that > it's not mine to make ;-) > > I guess if the lock acquire goes in the sky is not going to fall, > worst case this can get revisited later. So fwiw I would be leaning > towards accepting the patch as well for the time being. Again, agreed, and sorry if it wasn't clear. Thanks Demi. Oleg.