From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) (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 9A7083537E8 for ; Wed, 29 Apr 2026 03:15:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777432523; cv=none; b=Z3IRB9yNEBHxP8R1Ke5QCbDqMnJwpWOlX137ZtC1UGL42Akt04WNc+4+h9nYhrGBaYCQ0Px2+jEJqnv5O0C9ntakZoTTVjTTclWEUMmzG7becBLpLh28yMsr2M15p77ZlYEGNk2AIL92mTyfkTRfLACA2+iIsFySozv4mRDj5wM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777432523; c=relaxed/simple; bh=mgi3CbUj6197c1mBouEpDN0u4ZW2rRRfXoBDXDRxcUo=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=YsMi0KSRTysHfufnhw523hzGz0mV28XFzvflfg2XsTGNGCMjZcccT3xOQQnY+eDCIfcj1M0rUW0ravxDzmbtKU5SwCpgbwABDhwzw7O3QVzdvZ092WdM67X1qNbYw0sa8RwEXcFZu7Fk/Bqp2Xv42AE9PZo4tt1TnNpAr+XgYF8= 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=G5pTeOpl; arc=none smtp.client-ip=95.215.58.174 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="G5pTeOpl" Content-Type: text/plain; charset=us-ascii DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1777432517; 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=qU5tmzrS1IaHJYw4tCQ3LolTQkEkhN4AGDqa8zVsBOY=; b=G5pTeOpltJII7tZbmqmbXcd2mxNQW+oQBat6cBWM+NlWV218lDA++quyRMXu+eAmQF5aQp FlPTaucRkiYHiUnqppywHZevYmAx7s0qfE7hjjWhHt5+KUXS54L3k96qPoRzNHqZOf/kjY FvOukquIXnh4VKoapeLovcgSmMrPJoQ= 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 \(3864.500.181\)) Subject: Re: [PATCH 09/49] mm: panic on memory allocation failure in sparse_init_nid() X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: Date: Wed, 29 Apr 2026 11:14:14 +0800 Cc: Muchun Song , Andrew Morton , David Hildenbrand , Oscar Salvador , Michael Ellerman , Madhavan Srinivasan , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nicholas Piggin , Christophe Leroy , aneesh.kumar@linux.ibm.com, joao.m.martins@oracle.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <408EDCB4-7F65-4595-BE44-E23300FBD397@linux.dev> References: <20260405125240.2558577-1-songmuchun@bytedance.com> <20260405125240.2558577-10-songmuchun@bytedance.com> <9FD13495-58E8-4183-AAC0-48E50A694ADE@linux.dev> To: Mike Rapoport X-Migadu-Flow: FLOW_OUT > On Apr 28, 2026, at 21:08, Mike Rapoport wrote: >=20 > Hi Muchun, >=20 > On Tue, Apr 28, 2026 at 08:13:05PM +0800, Muchun Song wrote: >>=20 >>> On Apr 28, 2026, at 14:56, Mike Rapoport wrote: >>>=20 >>> On Sun, Apr 05, 2026 at 08:52:00PM +0800, Muchun Song wrote: >>>> When vmemmap pages allocation or usemap allocation fails, = sparse_init_nid() >>>> currently only marks the corresponding section as non-present. = However, >>>> subsequent code like memmap_init() iterating over PFNs does not = check for >>>> non-present sections, leading to invalid memory access (additional, >>>> subsection_map_init() accessing the unallocated usemap as well). >>>>=20 >>>> It is complex to audit and fix all boot-time PFN iterators to = handle these >>>> partially initialized sections correctly. Since vmemmap and usemap = allocation >>>> failures are extremely rare during early boot, the more appropriate = approach >>>> is to expose the problem as early as possible. >>>>=20 >>>> Therefore, use BUG_ON() to panic immediately if allocation fails, = instead of >>>> attempting a partial recovery that leads to obscure crashes later. >>>>=20 >>>> Signed-off-by: Muchun Song >>>=20 >>> Acked-by: Mike Rapoport (Microsoft) >>>=20 >>>> --- >>>> mm/sparse.c | 37 ++++++++----------------------------- >>>> 1 file changed, 8 insertions(+), 29 deletions(-) >>>>=20 >>>> diff --git a/mm/sparse.c b/mm/sparse.c >>>> index effdac6b0ab1..5c12b979a618 100644 >>>> --- a/mm/sparse.c >>>> +++ b/mm/sparse.c >>>> @@ -354,19 +354,15 @@ static void __init sparse_init_nid(int nid, = unsigned long pnum_begin, >>>> unsigned long map_count) >>>> { >>>> unsigned long pnum; >>>> - struct page *map; >>>> - struct mem_section *ms; >>>> - >>>> - if (sparse_usage_init(nid, map_count)) { >>>> - pr_err("%s: node[%d] usemap allocation failed", __func__, nid); >>>> - goto failed; >>>> - } >>>>=20 >>>> + if (sparse_usage_init(nid, map_count)) >>>> + panic("The node[%d] usemap allocation failed\n", nid); >>>=20 >>> Please consider using memblock_alloc_or_panic() in = sparse_usage_init(), it >>> would simplify the code even more. >>=20 >> Hi Mike, >>=20 >> Should we add a new function like memblock_alloc_node_or_panic? = Because >> we want to allocate vmemmap pages on the same node. >=20 > Heh, I missed the nid part :)=20 > There are a few _node_ or _nid_ allocation helpers in memblock, = starting to > add _nopanic for them would be overkill. Let's keep panic()s at call = sites. We can add a panic inside memmap_alloc() because it is used specifically = for memmap allocation. To some extent, this also reduces the number of = places where callers need to add a panic. What do you think? Thanks. >=20 >> Thanks. >>=20 >>=20 >=20 > --=20 > Sincerely yours, > Mike.