From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 E0E4A3B47C9 for ; Thu, 19 Mar 2026 21:39:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773956351; cv=none; b=hH6D4ZojDheAqrIoDnifX0MYZPpvJ/M5RAW8t1tmmuC3O79samfy+f0qhjsvonWVMBvtZy8HH7n5M3IjkB0OkTCbn296R7SFzBVbxyz8+r0tsCvUdF/T3uBCrUdelPwXgt5A18nq8QqVZXOG8cXHCJun3985UCNBaxJz0uxgt3o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773956351; c=relaxed/simple; bh=UdaDVgvKiMC1eZfeBt2Wh7IWv/BMZERz5riht0YyzIM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jOOthc9MhILlQW/Isjn60O9HP6969EAbqTn8kghmVHIan0ESoMSUZrkmYSIcLZ3pAok+ZV330SgNsMyIWwAS3rZYQe/sVcQQrmu+VCAo7LJphpivLsb+oadVxVeZsevr9/NS5ct7cP+gV7eWrXuqYOyb69ANJEdxl3HlNFwnteA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=bCJoKvMr; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="bCJoKvMr" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=NfAvuRAkXfTh0aD8fDGDPInZ2PzmkXCAe9B+2L0obpk=; b=bCJoKvMrE+n7v8Phg2+6TftTSy Z4gTRvb+7jTLCPTMoT2MSVfxu8FvPgYjOMl/QEe6/QPgFo/H2Hgg0S4mdNBd0GgHcmA9ND/rz+9TD PPasrCNfprfNPzhvGc9gqy5NSIgiDZBfuzR3ZaSvS3lUXF4Eo/XHX1Uv8MyGEdhq+rtjY0YzbG5yw XAQDeoZUkoduRWItj/Ph9u/p6qaLCihT1fStjxqZCBu8ZTyLNWuRXn4M6FePPhE+hjrUzzV8RcXf0 FGYUHWXT0md8JIKcLJPPEIWMsvMbkm+agFPFC465n/bddsWD8FWgPtDxsoED3LsV5Wktx1kvI+zty kHIiwKRA==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1w3L54-00000006k3I-3VIq; Thu, 19 Mar 2026 21:39:02 +0000 Date: Thu, 19 Mar 2026 21:39:02 +0000 From: Matthew Wilcox To: Brendan Jackman Cc: Andrew Morton , Michal Hocko , David Rientjes , Shakeel Butt , Vlastimil Babka , Suren Baghdasaryan , Johannes Weiner , Zi Yan , Harry Yoo , Hao Li , Christoph Lameter , Roman Gushchin , Uladzislau Rezki , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/5] mm: Switch gfp_t to unsigned long Message-ID: References: <20260319-gfp64-v1-0-2c73b8d42b7f@google.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: On Thu, Mar 19, 2026 at 06:40:59PM +0000, Brendan Jackman wrote: > I will paste the diff at the bottom. I _think_ all the problematic > expansions are downstream of struct xarray, but it's quite likely my > sense for problematic struct expansions is weak. Urgh, no, it's not all xarray. There's one in address_space which we're trying to shrink, not grow. There's one in struct sock too. I don't think this idea is worth it. There are other projects of greater or lesser churniess which will give us some flags back. For example, we could finish the GFP_NOFS and GFP_NOIO removal. We could finish the radix_tree -> XArray removal and get back three bits. That's five bits without even starting new projects, just finishing old ones.