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 5D46EE87855 for ; Tue, 3 Feb 2026 18:40:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6DC466B00A4; Tue, 3 Feb 2026 13:40:14 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 673736B00AB; Tue, 3 Feb 2026 13:40:14 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 589846B00AC; Tue, 3 Feb 2026 13:40:14 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 48A3D6B00A4 for ; Tue, 3 Feb 2026 13:40:14 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id E8DE88C07B for ; Tue, 3 Feb 2026 18:40:13 +0000 (UTC) X-FDA: 84404010306.18.1484B25 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf16.hostedemail.com (Postfix) with ESMTP id 5C7E2180008 for ; Tue, 3 Feb 2026 18:40:12 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=pdN9vlEc; spf=pass (imf16.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770144012; 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=cESLO7EPLjiYLM7kmKu59f6Z32mI6s3DLVo4D5WZgrg=; b=8A9kL4TJcPVJa/G0vM/e06XMZkNqY4ZBev/yw2l+KSa8mO9wi0/MQr2OSJUAsVdyeQfAcZ LqpuZ4la7mn0xFuS4tqHjSveKsdfL/ctQoM0Dv2xYKSOwQQ/RIzMZmpezr7LpDf5/fMWr7 PQ9R4ZUQYjIfPUnAvylaKrTQX7/VOSY= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=pdN9vlEc; spf=pass (imf16.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770144012; a=rsa-sha256; cv=none; b=fkPr5OWbqlEABoWNK0TzbjHE7AktJVD2jntOyTeFQp6lg4JNHOIBLP+8s7Jl6f+0hRDEqb ePW7rXoYxIBuzuoIjcJ8WgzdJD4JoLZH0KLZDjZqr4CtiKt5iHc3xtcx0lGnJdU69TWAXA ygZQCY2RR5+hDP8gGuvCfaZmCwzK8nY= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id C224360143; Tue, 3 Feb 2026 18:40:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 818ADC116D0; Tue, 3 Feb 2026 18:40:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770144011; bh=4+/Y4bSWbE/KBeeVwbdY/YvPY6O1OYogfJvl/txSdP0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pdN9vlEcMTWS0IHz5XjIZbkBpAFlujj1SKURJZHhVtdeiWxUn2xAKOG9Cy8o2KGH9 GXxEYEIeAs6jEuxdR88AQiTLOKv2KN3fXZvfVaZ2vfAXjpL0cpXVr7HB+ADp6cXXnq XhFO8i507bvvXpkv7lYSypQwlPsTDlk0FcWj874+U2fAR4RqN73uuLYX0NADaT6fA+ Okg4XNhSXLDrTqKCHUrO9gRPWmnMbdqJ++U670kaCpSUTTl3jeCymZ5r4RtNNamA2Y F7c5ntkqIazuMFolCLiO7MadWq43eavGxzzLsmOdr3VJiPMeSdhPWPfqTDWv78I9qV Gvnecne7Ya7MA== Date: Tue, 3 Feb 2026 20:40:06 +0200 From: Mike Rapoport To: Benjamin Herrenschmidt Cc: linux-mm@kvack.org Subject: Re: [PATCH] mm: Fix memblock_free_late() when using deferred struct page Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Stat-Signature: t5pez87d8fo55en15mttfsu6kw8b3gb7 X-Rspamd-Queue-Id: 5C7E2180008 X-Rspam-User: X-HE-Tag: 1770144012-936553 X-HE-Meta: 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 QyD+9BvT TXk2T2UhYglI/I+9qbdYGMAPPnnbSr+tOavMpzhR5wCwaFRWYfrwfL/GRgW0wPjLwSysh3Vk8nwZ6KwIRJ1wdPjUdxluUXiygnkIR0kUX/8H3G+rkKMpoUE+yMszzHaySNA4saIjE8NUIdkx6/hLaUaaIQ6F3/+KNS8v/fC9ZemS5cksWNgkqZoylDPMC3jhPeMPZYgtBqbgTEZtXhIgpFpwbHYLMSbWu5J2mhGra+YkfAaTS8PAi/2gAitDr4Gvwv/KxWnHgj97c5gERAslb/Jz5aDgGAvBHL9gl0Ftgpt0IAswSzxH7iVR/Em6eG809dvvfhjQgvuB1BSROlxF8feUF8Fbukq9/ioPA X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Ben, On Tue, Feb 03, 2026 at 07:02:08PM +1100, Benjamin Herrenschmidt wrote: > Currently, when using deferred struct page init, we may end up not > freeing the pages depending on where they are. Typically this happens > when efi_free_boot_services() tries to free UEFI Boot Services pages. > > We can hit the !early_page_initialised() test in memblock_free_pages() > since the deferred initializer hasn't even started yet. As a result we > drop the pages on the floor. > > Now, memblock_free_late() should only ever be called for pages that > are reserved, and thus for which the struct page has already been > initialized by memmap_init_reserved_pages(). > > So it should be safe to just free them normally and ignore the deferred > initializer, which will skip over them as it skips over anything still > in the memblock reserved list. > > This recovers something like 130MB of RAM on EC2 t3a.nano instances who > only have 512MB to begin with (as to why UEFI uses that much, that's a > question for another day). > > Signed-off-by: Benjamin Herrenschmidt > --- > mm/internal.h | 2 +- > mm/memblock.c | 6 ++++-- > mm/mm_init.c | 4 ++-- > 3 files changed, 7 insertions(+), 5 deletions(-) ... > @@ -2440,9 +2440,9 @@ void *__init alloc_large_system_hash(const char > *tablename, > } > > void __init memblock_free_pages(struct page *page, unsigned long pfn, > - unsigned int > order) > + unsigned int order, bool reserved) I've been thinking about after more coffee after our chat on IRC, and I believe we don't need the bool reserved here. Since the assumption that memblock_free_late() should be called only after buddy is initialized, all the reserved pages should have their memmap setup with PG_Reserved set. So we can use PageReserved() instead of passing the boolean. > { > - if (IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT)) { > + if (IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT) && !reserved) > { > int nid = early_pfn_to_nid(pfn); > > if (!early_page_initialised(pfn, nid)) -- Sincerely yours, Mike.