From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) (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 918C1379C40; Mon, 1 Jun 2026 12:38:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780317527; cv=none; b=WPkYIMIfCYfeioln38OLDK5NIbQ/vvP4mW5j4VNzZbYNTxeVooEo1JvYADlj16ap68+cwvW88TPkWl0lKZalK/0H3WYTkcOPJix7mDuequNdRYexFDpDMvhVl7Dkatiziu6u2sB9vPFLNEKWu6J8+ELYUBLCLuieRF2KSJX1bWw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780317527; c=relaxed/simple; bh=3az3TjNqqZkuQgZxxRqhlxK+9Py9j+5itmCceE1yE0k=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=M/W8VkutrK98TZoz3dhrkdPMCPnC40im77wYfT0s0WI6YESZrZKouj5WgwJJH2IcQCtlveb2RL5ZYP/92l+D8hGvdHdpM8zizSbpQSXjy/3qm05qw9zALnpamgHO6xDm3eanuBkht4y8xLTj5h3t7Wu22zWl5cXH08+m4JM32Vk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=t9X+k6Pk; arc=none smtp.client-ip=95.215.58.171 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) header.d=linux.dev header.i=@linux.dev header.b="t9X+k6Pk" Content-Type: text/plain; charset=us-ascii DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1780317513; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Y8Q9MsGaEY5Id3cDoyk/LMPpb+cY3ipFpIzkjqGDFMo=; b=t9X+k6PkHR5WsisChw0O5VpIHYqYLwjr9DFuC/tgFLuN5u0rKS+6y8bhT2MX1ghqTZTr+n DuMVk9niJvJLHdW7PBgKF1COtMWreGWe69fkyAbs03os4PWMGg/jK82UDtSe59liiNNRDy 2uJ7I61UVj726QpKC4J0NufWJLLoJoQ= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.600.51.1.1\)) Subject: Re: [PATCH v3 1/5] mm/sparse-vmemmap: provide generic vmemmap_set_pmd() and vmemmap_check_pmd() X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: Date: Mon, 1 Jun 2026 20:37:42 +0800 Cc: Muchun Song , Andrew Morton , Catalin Marinas , Will Deacon , Palmer Dabbelt , Paul Walmsley , Huacai Chen , Andreas Larsson , "David S. Miller" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, loongarch@lists.linux.dev, sparclinux@vger.kernel.org, Alexandre Ghiti , Albert Ou , WANG Xuerui , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Content-Transfer-Encoding: quoted-printable Message-Id: <0D4AF42F-37C5-4A76-9703-44ACC6374C48@linux.dev> References: <20260601084845.3792171-1-songmuchun@bytedance.com> <20260601084845.3792171-2-songmuchun@bytedance.com> To: "David Hildenbrand (Arm)" X-Migadu-Flow: FLOW_OUT > On Jun 1, 2026, at 20:22, David Hildenbrand (Arm) = wrote: >=20 > On 6/1/26 10:48, Muchun Song wrote: >> The two weak functions are currently no-ops on every architecture, >> forcing each platform that needs them to duplicate the same handful >> of lines. Provide a generic implementation: >>=20 >> - vmemmap_set_pmd() simply sets a huge PMD with PAGE_KERNEL = protection. >>=20 >> - vmemmap_check_pmd() verifies that the PMD is present and leaf, >> then calls the existing vmemmap_verify() helper. >>=20 >> Architectures that need special handling can continue to override the >> weak symbols; everyone else gets the standard version for free. >>=20 >> Signed-off-by: Muchun Song >> --- >> v2->v3: >> - Replace BUG_ON() with WARN_ON_ONCE() in vmemmap_set_pmd() >> --- >> mm/sparse-vmemmap.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >>=20 >> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c >> index 112ccf9c71ca..99e2be39671b 100644 >> --- a/mm/sparse-vmemmap.c >> +++ b/mm/sparse-vmemmap.c >> @@ -386,12 +386,17 @@ int __meminit vmemmap_populate_hvo(unsigned = long addr, unsigned long end, >> void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node, >> unsigned long addr, unsigned long next) >> { >> + WARN_ON_ONCE(!pmd_set_huge(pmd, virt_to_phys(p), PAGE_KERNEL)); >=20 >=20 > Not sure if a VM_WARN_ON_ONCE() would be appropriate. (then, we have = to move the > pmd_set_huge() out of the statement). I think it might be better to keep WARN_ON_ONCE here. This way, we can = still monitor for warnings in production while keeping the code simple. >=20 > Acked-by: David Hildenbrand (Arm) Thanks. >=20 >=20 > --=20 > Cheers, >=20 > David