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 8EE881DF251 for ; Mon, 6 Jan 2025 18:37:22 +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=1736188644; cv=none; b=iDH6K3iqGJZm9NPLWJ3gCjPGImZ9fad5ZVXwXKxMiTm4E85AR8+0hF82/lVhamTdLVxF8JZRJWp9ThIHZoPFMuB/Jt+BJEr6rYVlaumbxjyfSmbt8CEIIpXkPqCcT3SAs+WSLWPL8zO5kRRmCtkFft8W057cq2TfaDZph63LW6U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736188644; c=relaxed/simple; bh=DMyNrPw9s2h7q2z1rXh5aiad8faofsuC7wxYluJNqVY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=b0bgCRqxOp/mpkli1zqZoYh2AgqTmuSnMDyKGrR+x/eD9qRJ8s1bczmsRdlpwzKmnC/ppIR0GK/R3TKPFA10OE3PS9hnmDyzeUo7C7BaylBB3udOD19slk8Wg6SI3MQuyjAbBzcxTOgLYgvzEQrqD3TOPVmqu6Kq46qwo9d1sCI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=e0dLe7v1; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="e0dLe7v1" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736188641; 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=DMyNrPw9s2h7q2z1rXh5aiad8faofsuC7wxYluJNqVY=; b=e0dLe7v1N1/fkUprCTQ+z4xZSqAfarrBBAc44xYUYMEjz2218tXelvUTCGOQYZZzT1PNZB K1mdRijj4ZaB8ygpU58iDeiHkGhVtswTH0xposKaPimQ3BwYnSNDXryHFW2TFzH4EBavZw d7nkzPjfa31O3lyrZ8g6dciDiYD0lUw= Received: from mx-prod-mc-01.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-492-wiDTMSU3OgO1Q8VdFSmfHg-1; Mon, 06 Jan 2025 13:37:19 -0500 X-MC-Unique: wiDTMSU3OgO1Q8VdFSmfHg-1 X-Mimecast-MFC-AGG-ID: wiDTMSU3OgO1Q8VdFSmfHg Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C0E21195609E; Mon, 6 Jan 2025 18:37:16 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.102]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id B9626195606B; Mon, 6 Jan 2025 18:37:13 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 6 Jan 2025 19:36:51 +0100 (CET) Date: Mon, 6 Jan 2025 19:36:47 +0100 From: Oleg Nesterov To: Linus Torvalds Cc: Manfred Spraul , Christian Brauner , David Howells , WangYuli , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: wakeup_pipe_readers/writers() && pipe_poll() Message-ID: <20250106183646.GG7233@redhat.com> References: <20241229135737.GA3293@redhat.com> <20250102163320.GA17691@redhat.com> <20250106163038.GE7233@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 10.30.177.40 On 01/06, Linus Torvalds wrote: > > On Mon, 6 Jan 2025 at 08:31, Oleg Nesterov wrote: > > > > To be honest, I don't understand the wait_address check in poll_wait(), > > it seems that wait_address is never NULL. > > Oh, it seems to be historical. Yeah, please see my previous email. I think it must die, but needs another one-liner. > > That is what I tried to propose. Will you agree with this change? > > We can even use smp_store_mb(), say > > I think it's clearer to just use smp_mb(). OK, agreed, I'll send the trivial patch once I write the changelog. Oleg.