From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.129 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792650256; b=jbYRnLEEtAxQh4sSwlZ20KeYGmtyNhvRoGxv7d1EvBCSRdQzfK5RqlFNCMQQmqazaUJa 5GEEPQqUzzC09it9vfUMUe+CdAxJcB7frejSDhNMf+BkiwBCyzSWYCyqYDyPeve2QMqe4 SeXnnY/6crMJgyRfqiupY8JywgLFxS4U906/h1/hQ+BlrQOpq6UhWUClQ4FVZfwf6Jzl1 Tft2LrBaLJrxn+JihOYhzThEGohGYTHkMQm+RraXRVKnSdix2ZgJx9BO4ylz83CLj9wXd ahSaCs18yGyK37lmhbupTx5Ymw3F82Qvp4qvUMrXQgVc+J9G4/6vwjxWAnK4Osstv0Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792650256; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=NyrZtijtyGTQPq4lZyx+gSPus8J8tZcRW7L4bdstfYA=; b=neC4X+AIQc6zj4NDyuZ0XehnbnbBFwiJYH5ilOWsXraArBqZt3HeGm04viFDvFnrK0WN vJrNw7euvLMBWYiy8rNiieZ8YbFifIwYSTuf8vQIAMUKIzJOrjtZ4qdPM4dJTZD2o3El5 v70faISQK/u/KKSHLlEWQMPB3Ks63h7bcgeN+nCkNuhcCvG0cI+Pb5yTIrmoj856vk3tg 66/DNpBdyFURmCR2tBTbGQBpM+E9lIzwZT1sbvMy7zp+re8YHis6v6mxOeIkRTW9/Hs/I knONyth5hOtIlWk9tqw+tTLkXd6+X571eQj5mJpoystGPh92IQkPyfkacJ+4z4NYSlQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=XXLTTM3D; arc=none smtp.remote-ip=91.218.175.129 Received: from mta0.migadu.com (out-129.mta0.migadu.com [91.218.175.129]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 80D59606A319 for ; Thu, 22 Oct 2026 06:24:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 80D59606A319 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=XXLTTM3D X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=0zr077h6eg8GG3MPE83DyOxebLzAcrGd6CAuktOVwoA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792650252; v=1; x=1793255052; b=XXLTTM3DTVlB/dRJOBlmhavo5YA9IomhysFwM5JI0srZOJAGfSSNqvAZOP2W+zbvyPsRHkP1 LY6EsFg9HnihSidEcv+kgMNUEA7SaHKdlg2iPtLvjh2e1IN+4lwsuG2mPQhAVurrqSSj3sd2YoG guk3+hYDU2H+qg5YsMuDfHd4= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id ed6f83f251452fba; Thu, 22 Oct 2026 06:24:12 +0000 X-Mizu-Trace-ID: ed6f83f251452fba X-Migadu-Flow: FLOW_OUT From: Lance Yang To: songmuchun@bytedance.com Cc: osalvador@suse.de, akpm@linux-foundation.org, rppt@kernel.org, qi.zheng@linux.dev, lance.yang@linux.dev, jthoughton@google.com, david@kernel.org, muchun.song@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/12] mm: hugetlb_vmemmap: simplify vmemmap head page handling Date: Thu, 22 Oct 2026 14:24:01 +0800 Message-ID: <20261022062401.62096-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261020115824.823278-2-songmuchun@bytedance.com> References: <20261020115824.823278-2-songmuchun@bytedance.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Tue, Oct 20, 2026 at 07:58:15PM +0800, Muchun Song wrote: >The new head page is already tracked on the vmemmap page list before >remapping starts. Passing it separately gives the remap walker two >ways to refer to the same page and unnecessarily complicates its >interface. > >Use the page list as the single handoff mechanism for the head page, >removing the redundant state from the walker. > >No functional change intended. > >Signed-off-by: Muchun Song >--- > mm/hugetlb_vmemmap.c | 17 +++++++---------- > 1 file changed, 7 insertions(+), 10 deletions(-) > >diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c >index 8b3abb562599..164e93e980bf 100644 >--- a/mm/hugetlb_vmemmap.c >+++ b/mm/hugetlb_vmemmap.c >@@ -25,7 +25,6 @@ > * > * @remap_pte: called for each lowest-level entry (PTE). > * @nr_walked: the number of walked pte. >- * @vmemmap_head: the page to be installed as first in the vmemmap range > * @vmemmap_tail: the page to be installed as non-first in the vmemmap range > * @vmemmap_pages: the list head of the vmemmap pages that can be freed > * or is mapped from. >@@ -37,7 +36,6 @@ struct vmemmap_remap_walk { > struct vmemmap_remap_walk *walk); > > unsigned long nr_walked; >- struct page *vmemmap_head; > struct page *vmemmap_tail; > struct list_head *vmemmap_pages; > >@@ -208,10 +206,13 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, > pte_t entry; > > /* Remapping the head page requires r/w */ >- if (unlikely(walk->nr_walked == 0 && walk->vmemmap_head)) { >+ if (unlikely(walk->nr_walked == 0)) { >+ struct page *head; >+ > VM_WARN_ON_ONCE(!PageHead((const struct page *)addr)); > >- list_del(&walk->vmemmap_head->lru); >+ head = list_first_entry(walk->vmemmap_pages, struct page, lru); >+ list_del(&head->lru); > > /* > * Makes sure that preceding stores to the page contents from >@@ -220,7 +221,7 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, > */ > smp_wmb(); > >- entry = mk_pte(walk->vmemmap_head, PAGE_KERNEL); >+ entry = mk_pte(head, PAGE_KERNEL); > } else { > VM_WARN_ON_ONCE(!PageTail((const struct page *)addr)); > >@@ -289,7 +290,6 @@ static int vmemmap_remap_split(unsigned long start, unsigned long end) > * to remap. > * @end: end address of the vmemmap virtual address range that we want to > * remap. >- * @vmemmap_head: the page to be installed as first in the vmemmap range > * @vmemmap_tail: the page to be installed as non-first in the vmemmap range > * @vmemmap_pages: list to deposit vmemmap pages to be freed. It is callers > * responsibility to free pages. >@@ -298,7 +298,6 @@ static int vmemmap_remap_split(unsigned long start, unsigned long end) > * Return: %0 on success, negative error code otherwise. > */ /** * vmemmap_remap_free - remap the vmemmap virtual address range [@start, @end) * to use @vmemmap_head/tail, then free vmemmap which * the range are mapped to. Nit: could you update the @vmemmap_head/tail comment too, now that the head argument is gone? Nothing jumped out at me, so Reviewed-by: Lance Yang