From: Dan Williams <dan.j.williams@intel.com>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "Elliott, Robert (Persistent Memory)" <elliott@hpe.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Borislav Petkov <bp@suse.de>,
"Hansen, Dave" <dave.hansen@intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"Kani, Toshimitsu" <toshi.kani@hpe.com>,
"Vaden, Tom (HPE Server OS Architecture)" <tom.vaden@hpe.com>
Subject: Re: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages
Date: Thu, 22 Jun 2017 22:07:18 -0700 [thread overview]
Message-ID: <CAPcyv4igNoRZ1EJxeD01xwq5AU_hhEs4LoXs-8XA2mFbWDr5eA@mail.gmail.com> (raw)
In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F612DCCAF@ORSMSX114.amr.corp.intel.com>
On Wed, Jun 21, 2017 at 1:30 PM, Luck, Tony <tony.luck@intel.com> wrote:
>> Persistent memory does have unpoisoning and would require this inverse
>> operation - see drivers/nvdimm/pmem.c pmem_clear_poison() and core.c
>> nvdimm_clear_poison().
>
> Nice. Well this code will need to cooperate with that ... in particular if the page
> is in an area that can be unpoisoned ... then we should do that *instead* of marking
> the page not present (which breaks up huge/large pages and so affects performance).
>
> Instead of calling it "arch_unmap_pfn" it could be called something like arch_handle_poison()
> and do something like:
>
> void arch_handle_poison(unsigned long pfn)
> {
> if this is a pmem page && pmem_clear_poison(pfn)
> return
> if this is a nvdimm page && nvdimm_clear_poison(pfn)
> return
> /* can't clear, map out from 1:1 region */
> ... code from my patch ...
> }
>
> I'm just not sure how those first two "if" bits work ... particularly in terms of CONFIG dependencies and system
> capabilities. Perhaps each of pmem and nvdimm could register their unpoison functions and this code could
> just call each in turn?
We don't unpoison pmem without new data to write in it's place. What
context is arch_handle_poison() called? Ideally we only "clear" poison
when we know we are trying to write zero over the poisoned range.
next prev parent reply other threads:[~2017-06-23 5:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-16 19:02 [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages Luck, Tony
2017-06-19 18:01 ` Borislav Petkov
2017-06-21 17:47 ` Luck, Tony
2017-06-21 19:59 ` Elliott, Robert (Persistent Memory)
2017-06-21 20:19 ` Luck, Tony
2017-06-22 9:39 ` Borislav Petkov
2017-06-29 22:11 ` git send-email (w/o Cc: stable) Luck, Tony
2017-06-30 7:08 ` Borislav Petkov
2017-06-23 22:19 ` [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages Elliott, Robert (Persistent Memory)
2017-06-27 22:04 ` Luck, Tony
2017-06-27 22:09 ` Dan Williams
2017-08-16 17:18 ` [PATCH-resend] " Luck, Tony
2017-08-17 10:19 ` [tip:x86/mm] x86/mm, " tip-bot for Tony Luck
2017-08-17 22:09 ` [PATCH-resend] " Andrew Morton
2017-08-17 22:29 ` Elliott, Robert (Persistent Memory)
2017-08-17 23:32 ` Luck, Tony
2017-06-21 2:12 ` [PATCH] " Naoya Horiguchi
2017-06-21 17:54 ` Luck, Tony
2017-06-21 19:47 ` Elliott, Robert (Persistent Memory)
2017-06-21 20:30 ` Luck, Tony
2017-06-23 5:07 ` Dan Williams [this message]
2017-06-23 20:59 ` Luck, Tony
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