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 75D0F31987D for ; Mon, 24 Nov 2025 18:25:25 +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=1764008727; cv=none; b=Xb1w0tyfQg7LVI84OHDo0JVuoqrjy8hVdD1SEeNPogux43Ru68XJYGeC0YuVwquF88NT+wn+LEIKCuOXzf92GNty/1NkEim9NZiawce2Iz0YKVo6zC32iwT4elNUlutr6Xz5aHTTRVrYwXkg8SXgceibh0DheCXo3cYv+M40/G8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764008727; c=relaxed/simple; bh=B9PuOUokOzti6BWjCW5ZC70EIt7JF854IlUY1zHaJTQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RwgDFYP0Kwyhgh8t8PiyxpQd6rTbzpjTCTEzN1RGeWBzU3noXqbxScJ0+LCTGWWoUotZ19iRU/wne+edQCmhcBX9KPs+uPi8tiEjQKnkJ8/aHyc4/zXQz3r5LUIqkTR4zvtGWbAZq02v1BQCfAsB/GHkO7cGMnXXpcifpeyWsNM= 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=MnC5iGDO; 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="MnC5iGDO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1764008724; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=71o+PC47JuSXVbd2aeyANpOeKyMFPrn2rAw5uI8OTCw=; b=MnC5iGDO66Hjmvqf4WkiXyVyKC0+wQUhmwWSSEXB60yNVWXyTKY0DajFXLuKarcZcCsaiS swl7W4QZOvV+nsXeMo1aSoeHeTqIWeV5plOesDG6UtEdxmtT9duiUi2GRVU/Oe8MDAhuRb Y6lKW11JmWsAAd2TgzkgsrbffMfboUY= Received: from mx-prod-mc-05.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-398-02jQGE2dMku_MVsE_7IE3Q-1; Mon, 24 Nov 2025 13:25:22 -0500 X-MC-Unique: 02jQGE2dMku_MVsE_7IE3Q-1 X-Mimecast-MFC-AGG-ID: 02jQGE2dMku_MVsE_7IE3Q_1764008721 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 345C6195608D; Mon, 24 Nov 2025 18:25:21 +0000 (UTC) Received: from fedora (unknown [10.45.224.27]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 223621800451; Mon, 24 Nov 2025 18:25:18 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 24 Nov 2025 19:25:20 +0100 (CET) Date: Mon, 24 Nov 2025 19:25:17 +0100 From: Oleg Nesterov To: Mateusz Guzik Cc: brauner@kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org Subject: Re: [PATCH 2/3] ns: pad refcount Message-ID: References: <20251123063054.3502938-1-mjguzik@gmail.com> <20251123063054.3502938-3-mjguzik@gmail.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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 On 11/23, Mateusz Guzik wrote: > > On Sun, Nov 23, 2025 at 7:58 PM Oleg Nesterov wrote: > > > > On 11/23, Mateusz Guzik wrote: > > > > > > struct ns_common { > > > + struct { > > > + refcount_t __ns_ref; /* do not use directly */ > > > + } ____cacheline_aligned_in_smp; > > > > Cough... stupid question. Why not just > > > > refcount_t __ns_ref ____cacheline_aligned_in_smp; > > > > ? why do we need the anonymous struct? > > > > This would merely align the offset of the field, with the rest > directly following. Ah. I didn't bother to read the changelog and misunderstood the intent. OK, thanks. At least I have warned you that my question is stupid ;) Oleg.