From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9856A1098783 for ; Fri, 20 Mar 2026 13:23:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DD2CA6B0093; Fri, 20 Mar 2026 09:23:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DAA006B0095; Fri, 20 Mar 2026 09:23:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CBFEB6B0096; Fri, 20 Mar 2026 09:23:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id BC8C56B0093 for ; Fri, 20 Mar 2026 09:23:01 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 8BBE856731 for ; Fri, 20 Mar 2026 13:23:01 +0000 (UTC) X-FDA: 84566506962.18.A2534E5 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) by imf03.hostedemail.com (Postfix) with ESMTP id AC29820011 for ; Fri, 20 Mar 2026 13:22:59 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=google.com header.s=20251104 header.b="Ktc2KFA/"; spf=pass (imf03.hostedemail.com: domain of 3Mkq9aQgKCBE0rt13r4sx55x2v.t532z4BE-331Crt1.58x@flex--jackmanb.bounces.google.com designates 209.85.128.74 as permitted sender) smtp.mailfrom=3Mkq9aQgKCBE0rt13r4sx55x2v.t532z4BE-331Crt1.58x@flex--jackmanb.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774012979; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=GUDqodDk43yn3drXIlYhMhMKH+w2qm8q4A3+LPiJy1Y=; b=fWx2vnzLgezZqJJDm5B4xAu6V/lyiM+7OnfCG7wPco5cYS27pJHASLa9eekowHa1gMtgoD 9+7VqvBGjww76uG3GmOJV/GCivbQhxExELR7sYk+XxzpyQJQYx4ZsTOHWZ3e518QmFks8f HWSurjvX8IxO7RjOGIK284s6qK2TBe8= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774012979; a=rsa-sha256; cv=none; b=DLxlT6BKd2AijhASb7HJJALqfx23kj/S+NawCAF2zVhmOkXvuaPVesf03sZNygHq2WQxwF Hg5dZxjHtueyijuJzMQXp974sJhmeIcwDt+6+aoGdmfhwfH/wuSr+MG/SmAe9DcBbHhh5v O6yJq2uv2NGTKMG9Y8M2NDr85ghT870= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=google.com header.s=20251104 header.b="Ktc2KFA/"; spf=pass (imf03.hostedemail.com: domain of 3Mkq9aQgKCBE0rt13r4sx55x2v.t532z4BE-331Crt1.58x@flex--jackmanb.bounces.google.com designates 209.85.128.74 as permitted sender) smtp.mailfrom=3Mkq9aQgKCBE0rt13r4sx55x2v.t532z4BE-331Crt1.58x@flex--jackmanb.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com Received: by mail-wm1-f74.google.com with SMTP id 5b1f17b1804b1-486fa35b005so18600685e9.2 for ; Fri, 20 Mar 2026 06:22:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1774012978; x=1774617778; darn=kvack.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=GUDqodDk43yn3drXIlYhMhMKH+w2qm8q4A3+LPiJy1Y=; b=Ktc2KFA/76+Vh27yb2IOgHZqWhGwF6Xldkr59BeItQrzIcmj5hWC8cOj8WOAPyYV3j 9lfDWEvkScn8H5sBRvTz8C+blvMkKTKs/sWn3R/p/4zPpTNyNi3kp480EhNVE0fUYG6w sKLbv06h4BuXdl9QxA9Yav2LyoUGPa5QRab/mT1DcF9g+h56GbSHzGfE+Pp8cWAO7FBv NPipyn+kHVRpeFjvRMk5RMVeY+VbnTv5SiSfx6LuFz86city/v91/aXvprgJvygXMy7T ljygBPeYibKrmU+Xk9nTPgvFwnl16gJisJXdmWmJFYBdUnwCP1GqoFXg/YJkCvBHtevK QnVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774012978; x=1774617778; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=GUDqodDk43yn3drXIlYhMhMKH+w2qm8q4A3+LPiJy1Y=; b=AX6vd1+r67NUwP9OlSFD6+gY2keOiQwrED9Uw1m3x/2eP/0U087jJBajrrFsrUkSlB VFeEbngFabxSysHM2uOQwiMfdL6GLS4mzcsC0TshBP9VOUXi2bJhZFxLJkE2oWDm8UIe +NXS5Zk+Pt1Kg2+K9/fTLzT/KLLpA2V74tb0EymJ0gS6Ll5eXigJVMSUlDoQn3ykwjDR eb1pJviuC9MTdDhgcJNoBXzmalh93QrKQ+JRAt7SFxPCP2Jc2eyh5/WwXUF5UvtYpnFY hOfR4vPBYZoe57eW3ljAPK30L64Zh9YTnilzOtD61oxJUlgazXEi4I9zwl1B/waGUowk dL3w== X-Forwarded-Encrypted: i=1; AJvYcCUqMlC838ZdV4kNCbneVdU2eq051+l8n4ia9Pp2j+egJZeutolrIsFElEeNu8Awv/qE7CDAxLSjZg==@kvack.org X-Gm-Message-State: AOJu0YyEIOZ+WUWsTOWYtmx2SjNKw4BvC2p3Cheq1AmpsGP6pAAmJ4/c fNc63AEgxrcBP4py/IiFRJgPZ8ciRaxsOTveIHIeoTmWeEQ1Nv7D9GM9QmJKmzwcdzqk51PzXrW XFXcX6SiM5lKTVA== X-Received: from wmbdx7.prod.google.com ([2002:a05:600c:63c7:b0:47d:5bef:a379]) (user=jackmanb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:c167:b0:486:fab9:a578 with SMTP id 5b1f17b1804b1-486fedc3843mr45048705e9.11.1774012978000; Fri, 20 Mar 2026 06:22:58 -0700 (PDT) Date: Fri, 20 Mar 2026 13:22:57 +0000 In-Reply-To: Mime-Version: 1.0 References: <20260319-gfp64-v1-0-2c73b8d42b7f@google.com> X-Mailer: aerc 0.21.0 Message-ID: Subject: Re: [PATCH 0/5] mm: Switch gfp_t to unsigned long From: Brendan Jackman To: Brendan Jackman , Matthew Wilcox , Cc: Andrew Morton , Michal Hocko , David Rientjes , Shakeel Butt , Suren Baghdasaryan , Johannes Weiner , Zi Yan , Harry Yoo , Hao Li , Christoph Lameter , Roman Gushchin , Uladzislau Rezki , , Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: bkttgwnm1a9ub1pwbe17q7riehtkm83o X-Rspam-User: X-Rspamd-Queue-Id: AC29820011 X-Rspamd-Server: rspam12 X-HE-Tag: 1774012979-47923 X-HE-Meta: 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 qgWYsJLT 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri Mar 20, 2026 at 9:48 AM UTC, Brendan Jackman wrote: > On Thu Mar 19, 2026 at 9:39 PM UTC, Matthew Wilcox wrote: >> 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. > > Oh sorry I just assumed that one was xa_flags. > >> There's one in struct sock too. > > Huh, I suspect I am embarassing myself with this question, but why are > we sensitive to the size of struct sock? It's currently 784 bytes in my > build. Are the adjacent fields very hot, and we need to look up the GFP > flags from hot paths? > >> 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. Oh, but also couldn't we get those 3 back by expanding struct radix_tree_root as I suggested a few messages back: -#define radix_tree_root xarray +struct radix_tree_root { + struct xarray xarray; + gfp_t gfp; +}; That seems to make sense as a way to avoid the xa_flags overload even if gfp_t doesn't grow. (_If_ we can tolerate radix_tree_root expansion, which I have no idea about. Otherwise, yeah seems like finishing the radix-tree migration is a good path to more GFP flags).