From: Ingo Molnar <mingo@kernel.org>
To: Toshi Kani <toshi.kani@hpe.com>
Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
bp@alien8.de, henning.schild@siemens.com,
linux-nvdimm@lists.01.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/mm/vmfault: Make vmalloc_fault() handle large pages
Date: Tue, 9 Feb 2016 10:10:03 +0100 [thread overview]
Message-ID: <20160209091003.GA10774@gmail.com> (raw)
In-Reply-To: <1454976038-22486-1-git-send-email-toshi.kani@hpe.com>
* Toshi Kani <toshi.kani@hpe.com> wrote:
> Since 4.1, ioremap() supports large page (pud/pmd) mappings in x86_64 and PAE.
> vmalloc_fault() however assumes that the vmalloc range is limited to pte
> mappings.
>
> pgd_ctor() sets the kernel's pgd entries to user's during fork(), which makes
> user processes share the same page tables for the kernel ranges. When a call to
> ioremap() is made at run-time that leads to allocate a new 2nd level table (pud
> in 64-bit and pmd in PAE), user process needs to re-sync with the updated kernel
> pgd entry with vmalloc_fault().
>
> Following changes are made to vmalloc_fault().
So what were the effects of this shortcoming? Were large page ioremap()s unusable?
Was this harmless because no driver used this facility?
If so then the changelog needs to spell this out clearly ...
Thanks,
Ingo
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-02-09 9:10 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-09 0:00 [PATCH] x86/mm/vmfault: Make vmalloc_fault() handle large pages Toshi Kani
2016-02-09 9:10 ` Ingo Molnar [this message]
2016-02-09 9:53 ` Henning Schild
2016-02-09 10:22 ` Ingo Molnar
2016-02-09 12:26 ` Henning Schild
2016-02-09 16:08 ` Toshi Kani
2016-02-09 16:03 ` Toshi Kani
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160209091003.GA10774@gmail.com \
--to=mingo@kernel.org \
--cc=bp@alien8.de \
--cc=henning.schild@siemens.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-nvdimm@lists.01.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=toshi.kani@hpe.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).