From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f53.google.com (mail-wr1-f53.google.com [209.85.221.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9814A149C7B for ; Wed, 16 Apr 2025 13:08:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744808942; cv=none; b=WavMAsi5RUlo29MLE10JLSz0k9BEKtca654iPRJ56xoyiL2N4z2ABbTvQdjyPWEpp05WRj0+TPLWYA6jBiHHq0WbM20XwEHv77nn9S1+yex4o6ishUMzlCXmCHmcRdowrU5eikXx2t22XWKOCXwlKoekTxa/beSYPEmd0boF48s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744808942; c=relaxed/simple; bh=p/iyWC6HvCPY2TgwnlCPzsZ6CCy+XnmL1Lk+5LmCGhU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Z5vBu1EadjvaWXQxU9qUvYN3PJbEcvuWFDk6+U3t/bBxeQhdS3XCodkb1sAFevbm92Tb84XIXpP0BjzHqZi8X2dtc64Tme/S7wKPtn8xxf06+HNUaxIafUh25e9uap65R2IuXxOkKRhDfZnK1qlYAp6YCAzcRCPRRllj2/IT28k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=C1mJ+ovf; arc=none smtp.client-ip=209.85.221.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="C1mJ+ovf" Received: by mail-wr1-f53.google.com with SMTP id ffacd0b85a97d-39ee57c0b8cso530761f8f.0 for ; Wed, 16 Apr 2025 06:08:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1744808938; x=1745413738; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=0Q94yOoOApKItt1hLRlRluZyloOVNtuhZPjQvabIyLY=; b=C1mJ+ovfwyUxOkxUy1ZTdUzVTdLc0RTLKxkJc8+vB2fqvW4KW1R/A6d70EaWq8dAms vGioGUTBt716F9p8sEqqoaGcb0DtqmksNlpiVqKZwPtjaytNly6ntmO2kBojQTn/6z4/ xPgmTmUFp7r11MVZKuS2D5DS5PoIFQIzADzxHN1IfFT/sRqEr675OUX23QRIE4VBz1Ft foTbQGc1OgS3PZe3oJkEZwECeFzN719qLs2Q8UNg6/4pbQj4Z1g6osxMRBWMHxHe7MRL PWmDqP6/xmBGNwtvMKYDkaFp1XSvhFx3/9m6FZXYkkVRgeScd8GLSPYcuPZB7CFu6u9L wM/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744808938; x=1745413738; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=0Q94yOoOApKItt1hLRlRluZyloOVNtuhZPjQvabIyLY=; b=d6TXTEj275ma1zjaqa2Ce9QZr/nznoh+ZdC06Vza+W+PY/LP+TOlJsR7T3xFc9GDOb YqpHqa17TVjhLavTAfUxa7GeABgsU5WJQkIgf+tER+k4JZirNrc4pD0jhDPbS7U2a7Tg DzQ3DBJdwm9ftpezMLCmn1vrl0ainMmbwsGxJqCk4VelPJlhFT2zF0IVplf33kd1wExD MEozuQDJN2deYxZ+0jXqyJuaIasq37AwMOcLdwYqu/aV5rdb1geeVcLAiFsTqpq6y49a weBsFpYi/wlPhSq9UPxElB4Foqqnmmn87f75dSOM6nI4cvmW6nBcnX3IsLBNep57W5CR UWGw== X-Forwarded-Encrypted: i=1; AJvYcCV/WqjDm21cMZqhLyzOiG+R7MdamvUAm6xZjJtBlsu38MkZtGyZvXp/ZDDqazDKRLNSumtNEJxuA2k=@vger.kernel.org X-Gm-Message-State: AOJu0YwpjzNELJSNKol2EXezMHI4ysOGYh0jLvmT/d9659CXSWsnaVph LdbVKLjy0GbZaeE8VrNV2AJwlsDmVqzyvQX/vVVFyW73n5KWnGfJW62dHSkeEsU= X-Gm-Gg: ASbGncsArRPYIyYDuYjTkKptV80XS2Dkgm4yITnyTP2s2qZfjYatNJM1GJOezLZU78t QYnonAk/NlWWufLsAZH+4RePT0atIagoNexX9F/TdoWuIyjtj4OHGxEEedH+u/grn3TS5cWn6zB VdzLtxa6Z+i5/GNhQZ1K3q8SDqD8GaRqBAYlIxleqvKdma6IjwEJs5lqTY7POo4lUPVo9/PTW8q 4qvsQF/CYa8CSUVqYeAgmuHg8VT1drHPd626DUfCOxajZl0u0X4QvNdUH/dZkb5+U5Cl/sozytl f9Olz3Xx2+ovVDu6WX9jY0gQ4RjYtai8dB6dkHJEjxi81MlBstWxxECe7FLV0sYhZuBlKQOrkSx UdRs6SmY= X-Google-Smtp-Source: AGHT+IHOsJk1QtB5kEoSZrYAYpRPaEigS+0jlbTDIIkpc2LnRk68oJlodSN8FXDP3R34O6sthrpyNg== X-Received: by 2002:a05:6000:4021:b0:39c:223f:2770 with SMTP id ffacd0b85a97d-39ee5b18646mr1809040f8f.15.1744808937399; Wed, 16 Apr 2025 06:08:57 -0700 (PDT) Received: from ?IPV6:2001:a61:1350:fd01:ac0d:cf4f:2906:b446? ([2001:a61:1350:fd01:ac0d:cf4f:2906:b446]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39eaf43cd17sm17165723f8f.78.2025.04.16.06.08.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Apr 2025 06:08:56 -0700 (PDT) Message-ID: <65bd42ee-ecbc-4a23-9036-42358aa086df@suse.com> Date: Wed, 16 Apr 2025 15:08:53 +0200 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] usb: core: warn if a GFP zone flag is passed to hcd_buffer_alloc() To: Petr Tesarik , Oliver Neukum Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250320154733.392410-1-ptesarik@suse.com> <20250325134000.575794-1-ptesarik@suse.com> <2025041110-starch-abroad-5311@gregkh> <20250414090216.596ebd11@mordecai> <522b3049-8e7f-41d4-a811-3385992a4d46@suse.com> <20250416094807.2545efd8@mordecai> <20250416124736.3ac2bd55@mordecai> Content-Language: en-US From: Oliver Neukum In-Reply-To: <20250416124736.3ac2bd55@mordecai> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 16.04.25 12:47, Petr Tesarik wrote: > If I stay with the USB buffer allocations, AFAICS the mem_flags > parameter should be used only for non-zone flags. If you specify, > GFP_DMA here, it will have no impact whatsoever on allocating DMA > buffers. It may unnecessarily allocate from the DMA zone for doing PIO. Yes. But we should not limit enforcement of such a _new_ policy to one method in order to fix a hypothetical issue. There is just no need for action. > Now I think I should really write an article for LWN to debunk some > myths about GFP_DMA. Well, if you go to that trouble an explanation of why memflags are passed in USB at all and how DMA works in general would be productive. Regards Oliver