From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (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 281F4330D2A for ; Tue, 28 Apr 2026 07:03:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777359806; cv=none; b=GbhNrylPfmByder69hh0TkfK7iUXW006sYv8i/3pHZJPGqQfKe73aJiidIY4sc/tsDhpTVK/G/KzcpMaQCBaKvsyVDil/mnXHspENp/2KzaIMojV3SeWYQGNeCjhtxClu7+e7TzRoalVtdAeQNPWGc/zgrukvJ8cDy/0AE3/v5M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777359806; c=relaxed/simple; bh=iVTExiQYxwZp82qYQLBFhLPRku7bUmf0S6xB51t0BG8=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=uQsT8aqMdMLqACoYy0SJyPqNH/nQdA3atr6wBvq23rYItFDGaplR083jU5RzW5ObwMQGMwbZxbsB9LlZFaDbncJ4C8AuVo+3GQNBAPI/A01a/ewMhdaBoRkJZ3q0A4tlpVHRax90BohMEAdl/mOloD4h9uGpZWAfMN2KAVJ6e+4= 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=uEMowhdT; arc=none smtp.client-ip=95.215.58.180 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="uEMowhdT" Content-Type: text/plain; charset=utf-8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1777359803; 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=m65F23/62CDX/gfV+DJ/SyWW1JLoAdNRr+rVnoGxkFY=; b=uEMowhdTmYivW6Yp0mQBkEN0edND6tucf0nNvmJCZ/QVuvXHHewn1r5qXw5/JMu/dqG6wm rcH7y0jjypRkLS5LeeLRPQgyO9AbGnuES3UYZh2lh89R74LUQunJaKdHqwlXmG9noWSCD2 UQh11NwUPbATYpKCGFyHnHOvZRRzuK8= 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: Tue, 28 Apr 2026 15:02:14 +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: <96DB49C7-A7C2-4F53-8321-FF4A4ECDFF95@linux.dev> References: <20260405125240.2558577-1-songmuchun@bytedance.com> <20260405125240.2558577-10-songmuchun@bytedance.com> To: Mike Rapoport X-Migadu-Flow: FLOW_OUT > 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) Thanks. >=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. Hi Mike, Yes. I have several more updates for v2. Please hold off on reviewing the current version to avoid wasting your time; I=E2=80=99ll send the = new one over shortly. Thanks.=