linux-kernel - RE: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages

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]

Date:   Fri, 23 Jun 2017 22:19:35 +0000
From:   "Elliott, Robert (Persistent Memory)" <elliott@....com>
To:     "Luck, Tony" <tony.luck@...el.com>, Borislav Petkov <bp@...e.de>
CC:     Dave Hansen <dave.hansen@...el.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Yazen Ghannam <yazen.ghannam@....com>,
        "Kani, Toshimitsu" <toshi.kani@....com>,
        "'dan.j.williams@...el.com'" <dan.j.williams@...el.com>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>
Subject: RE: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of
 poison pages

> > > +	if (set_memory_np(decoy_addr, 1))
> > > +		pr_warn("Could not invalidate pfn=0x%lx from 1:1 map \n",

Another concept to consider is mapping the page as UC rather than
completely unmapping it.

The uncorrectable error scope could be smaller than a page size, like:
* memory ECC width (e.g., 8 bytes)
* cache line size (e.g., 64 bytes)
* block device logical block size (e.g., 512 bytes, for persistent memory)

UC preserves the ability to access adjacent data within the page that
hasn't gone bad, and is particularly useful for persistent memory.

---
Robert Elliott, HPE Persistent Memory