From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 87C99322B8F; Thu, 15 Oct 2026 10:02:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792058535; cv=none; b=Fw9p7wM4dsq6w5ULDGix3hxJ7tQRjvYKYgndrSLI517lMVw8N4GSCV7fo1WMn7sID1xz4cOu4bS14IYZbYk+lpHnsWqGtrpkvEcVePZA9dvOQJzavIvp2c3aX3N56WU8cpjnsF2RKqiUFmll9OoQAJQgg6efKjO/eTq9x+WDCoA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792058535; c=relaxed/simple; bh=T33GmSIa8ZXcZcboQ6eeHkUwMBfXwo2O+4ayOOp6DVQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jnXUW6ordD9JJOl1rm0h71oZsZda26V9wfN/xvf/eUrINpvN1GtRVVk2L22YcYsN4Z5W6VbeqS7j4ZSTbEDieT63zAtv8JosOA/73NKI+e2CqgzaHgxV7g2CAhQ0dqZRin8ZMVcnNVKvslSquFmNvBpuTCnjeoTDsxMDeaD+6Wg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Iko2b0kk; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Iko2b0kk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 256631F000C4; Thu, 15 Oct 2026 10:02:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792058531; bh=5Pqi9+FJ5ewTDOrXx6NJLaiZDN05LqWUpfO1uWA0Wgw=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Iko2b0kk0bIGk8QVSE1lc+78pqVzKqFb/c6PX07rt8o/L64rRlfyLiAwQAvvm2D2f F1G7/yeHsYCSltPOKzyG4dRvWl2wAq1Ha0lYOadrYRg8C/7VlDR3MhOfmEOuyYI3O6 1TR/hjFFUBSJGsWQ/bRc4w/sr6l1jJFyO4MqJ+MrCO//h0SsbVvwQv9lwP5HZZqHsq xlBSvSeMPrQFaVZ5njxYJNPyR9/+2VYRrfm/xfsKCfbTvAsehGYV3ndjTxJxoN5hVZ jav4uXA7zZ5PVeUMKQEjlF2ppEl4ByteA+ZH9MsjRxFrCuLnIOu3m/+n7yq50ydTGC 1V4mGjBjkdvAg== Message-ID: <1f36992d-00c1-4f74-9947-b543ed794cf0@kernel.org> Date: Thu, 15 Oct 2026 12:02:06 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/6] mm: pass alloc_flags through folio, filemap, and bulk allocators Content-Language: en-US To: Gregory Price , "David Hildenbrand (Arm)" Cc: linux-mm@kvack.org, willy@infradead.org, brendan.jackman@linux.dev, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@meta.com, jack@suse.cz, akpm@linux-foundation.org, ziy@nvidia.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, ying.huang@linux.alibaba.com, surenb@google.com, mhocko@suse.com, hannes@cmpxchg.org References: <20260923211041.3127588-1-gourry@gourry.net> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/10/26 01:28, Gregory Price wrote: > On Fri, Oct 09, 2026 at 10:55:05PM +0200, David Hildenbrand (Arm) wrote: >> I do agree that two sets of flags is suboptimal, but likely more flexible. I >> guess an alloc_flags only interface is not easily possible ... Agree with the alloc_flags option of all the other options. >> I do wonder whether it should be: >> >> typedef int __bitwise alloc_flags_t; >> >> instead of "unsigned int alloc_flags". >> >> ... while at it Can't hurt, but given how it's internal only it didn't seem that urgent as for gfp. > Does it make sense to leave alloc_flags to internal-only state > and just implement a new flag field? > > gfp_t -> describe the page (fully public) > req_t -> describe the allocator behavior (mm-internal only) > alloc_flags -> internal allocator state only Maybe in that case the remaining alloc_flags should just become 1-bit fields directly in struct alloc_context so we don't manage 3 separate bitwise types. Or more bits in case of ALLOC_WMARK? Depends on how much work this would be (and if you want to do it) and how the result would like. > typedef int __bitwise pa_req_t; /* Page Allocator Request Flags */ > > #define PA_REQ_DEFAULT 0 > #define PA_REQ_NOLOCK BIT(0) /* from ALLOC_NOLOCK */ > #define PA_REQ_NO_CODETAG BIT(1) /* from ALLOC_NO_CODETAG */ > #define PA_REQ_SPREAD_DIRTY BIT(2) /* from __GFP_WRITE */ > #define PA_REQ_DEFER_INIT BIT(3) /* from __GFP_SKIP_ZERO */ > #define PA_REQ_ZERO_TAGS BIT(4) /* from __GFP_ZERO_TAGS */ > #define PA_REQ_NO_FALLBACK BIT(5) /* select no fallback list */ > #define PA_REQ_NO_OOM BIT(6) /* do not oom */ > > Off the bat we recover 2 ALLOC flags and 3 GFP flags. Possibly more with > a bit more work. > > Then we get: > > #define PA_REQ_PRIVATE BIT(7) /* allow private node allocation */ > #define PA_REQ_UNMAPPED BIT(8) /* page must be unmapped */ > > And we might not even need a new zonelist for private nodes in this case > as long as we require internal users to pass PA_REQ_PRIVATE and add a > function like > > folio_alloc_private(void *owner, ...) { > /* validate (pgdat->owner == owner) before allowing allocation */ > __folio_alloc(..., req | PA_REQ_PRIVATE | PA_REQ_NOFALLBACK, ...); > } > > User still has the option to request NO_OOM via __GFP_THISNODE :] > > ~Gregory