linux-kernel - Re: [PATCH v2 1/3] mm/huge_memory: don't ignore queried cachemode in vmf_insert_pfn

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <684a58bf34666_2491100d7@dwillia2-xfh.jf.intel.com.notmuch>
Date: Wed, 11 Jun 2025 21:34:07 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: David Hildenbrand <david@...hat.com>, <linux-kernel@...r.kernel.org>
CC: <linux-mm@...ck.org>, <nvdimm@...ts.linux.dev>,
	<linux-cxl@...r.kernel.org>, David Hildenbrand <david@...hat.com>, "Andrew
 Morton" <akpm@...ux-foundation.org>, Alistair Popple <apopple@...dia.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, "Liam R. Howlett"
	<Liam.Howlett@...cle.com>, Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport
	<rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko
	<mhocko@...e.com>, Zi Yan <ziy@...dia.com>, Baolin Wang
	<baolin.wang@...ux.alibaba.com>, Nico Pache <npache@...hat.com>, Ryan Roberts
	<ryan.roberts@....com>, Dev Jain <dev.jain@....com>, Dan Williams
	<dan.j.williams@...el.com>, Oscar Salvador <osalvador@...e.de>,
	<stable@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] mm/huge_memory: don't ignore queried cachemode in
 vmf_insert_pfn_pud()

David Hildenbrand wrote:
> We setup the cache mode but ... don't forward the updated pgprot to
> insert_pfn_pud().
> 
> Only a problem on x86-64 PAT when mapping PFNs using PUDs that
> require a special cachemode.

This is only a problem if the kernel mapped the pud in advance of userspace
mapping it, right?

The change looks good.

Reviewed-by: Dan Williams <dan.j.williams@...el.com>

...but I am struggling with the scenario where this causes problems in
practice, where vm_page_prot is the wrong cachemode.