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 5CDD53DB983; Thu, 10 Sep 2026 07:53:25 +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=1789026806; cv=none; b=Jyw6sF9PVYfp5OwPscsatQuJvTdihkqQJMg5QX4x6OqJkZSL7/cGewwTOXclMtIWGuKVeJBhGgJulV1FSrplwXcCWVDXM4XecF2ZbEllxXdBC3cuDl+0UfhjCgrGpbXqIapdJw0FBlv0vurBXm5tIxCnA1J8utGmWXVZWddxT4c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789026806; c=relaxed/simple; bh=RSdCzkYrR5h/cJKalhMpI2wCIS1TDFpoO7krbevk3UM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=t1m7EeKj/cKkj4O0tYBcYsMkJDZjFgwr3dbzYSKfq9TpbDQBpi+jjLwSnbX2OsOQM35GAdyZrRDXKTC+KnrMS17lI+goNTxPB3o1iYQAdRatHfrfXfP3Cm5do1JX4jk71Pt9afwQ6MyDl7tSin8ZRDRTiQPNTOMgxNO4sKIEflc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PhV9mmVJ; 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="PhV9mmVJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E5A31F0089A; Thu, 10 Sep 2026 07:53:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789026805; bh=KRB916lj3l/kaoIROZgvEq5UY1QI+PbW3M7goiEHvOE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=PhV9mmVJj8HaWPabBYhvMSsgZMBm/iNmNrVKbOAwBrvBUDAS3kQzPqHIsoQoErIZ+ kUhMB7AiLoWxhuQwHEtRsLJ+TcYl/HFfQkIH0iosT9Vlfk/ZtkRrN7667NE1qNLDHA 3AWysrlhQkVoPGtjqmN2K0E1FN0qTC1lIjb5S6M3W7UXsmbTNfwG4r9hY0DDdOA4r9 39KEZ4ww4zwmSXesWcJRj8jYzQ6s5AlQXWTz5KJiYZ7+480u/c5Ev5cs/GMeJ6Ikl5 m+vjuqsmPW9pRo8g5Hx1mk/LubFTe1VuqHcmHEu7leARLCHxOafE/t+y+DHmEzvslm eEdS7mvZL1hnw== Message-ID: Date: Thu, 10 Sep 2026 09:50:26 +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: [PATCH v2 03/11] mm/sparse-vmemmap: open-code init_compound_tail() To: Muchun Song , Andrew Morton , Oscar Salvador , Madhavan Srinivasan , Michael Ellerman , Jonathan Corbet Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, Muchun Song , Lorenzo Stoakes , Mike Rapoport , Qi Zheng , Nicholas Piggin , Christophe Leroy , Randy Dunlap References: <20260908030335.96549-1-songmuchun@bytedance.com> <20260908030335.96549-4-songmuchun@bytedance.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/8/26 05:03, Muchun Song wrote: > init_compound_tail() is only used by vmemmap_shared_tail_page(), where > the shared tail page setup intentionally passes NULL as the compound head. > > Keeping this helper in mm/internal.h exposes that special case to the rest > of the MM code and can make the NULL head argument look generally valid. > Open-code the initialization at the only call site so the special-case use > stays local to sparse vmemmap optimization. > > No functional change intended. > > Signed-off-by: Muchun Song > Acked-by: Qi Zheng > --- > v2: > - Collect Acked-by from Qi Zheng > --- > mm/internal.h | 9 --------- > mm/sparse-vmemmap.c | 5 ++++- > 2 files changed, 4 insertions(+), 10 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index da14c56fb24e..0dca33db068f 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -786,15 +786,6 @@ static inline void prep_compound_tail(struct page *tail, > VM_WARN_ON_ONCE(tail->private); > } > > -static inline void init_compound_tail(struct page *tail, > - const struct page *head, unsigned int order, struct zone *zone) > -{ > - atomic_set(&tail->_mapcount, -1); > - set_page_node(tail, zone_to_nid(zone)); > - set_page_zone(tail, zone_idx(zone)); > - prep_compound_tail(tail, head, order); > -} > - > #if defined CONFIG_COMPACTION || defined CONFIG_CMA > > /* > diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c > index 70143dd8b579..e453ce4675a0 100644 > --- a/mm/sparse-vmemmap.c > +++ b/mm/sparse-vmemmap.c > @@ -189,7 +189,10 @@ struct page __ref *vmemmap_shared_tail_page(unsigned int order, struct zone *zon > for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++) { > page = (struct page *)addr + i; > mm_zero_struct_page(page); > - init_compound_tail(page, NULL, order, zone); > + atomic_set(&page->_mapcount, -1); > + set_page_node(page, zone_to_nid(zone)); > + set_page_zone(page, zone_idx(zone)); > + prep_compound_tail(page, NULL, order); > } > > page = virt_to_page(addr); Acked-by: David Hildenbrand (Arm) -- Cheers, David