From: Ingo Molnar <mingo@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Toshi Kani <toshi.kani@hp.com>,
hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com,
arnd@arndb.de, linux-mm@kvack.org, x86@kernel.org,
linux-kernel@vger.kernel.org, Elliott@hp.com
Subject: Re: [PATCH v2 0/7] Kernel huge I/O mapping support
Date: Tue, 24 Feb 2015 09:09:27 +0100 [thread overview]
Message-ID: <20150224080927.GB19069@gmail.com> (raw)
In-Reply-To: <20150223122224.c55554325cc4dadeca067234@linux-foundation.org>
* Andrew Morton <akpm@linux-foundation.org> wrote:
> <reads the code>
>
> Oh. We don't do any checking at all. We're just telling
> userspace programmers "don't do that". hrm. What are
> your thoughts on adding the overlap checks to the kernel?
I have requested such sanity checking in previous review as
well, it has to be made fool-proof for this optimization to
be usable.
Another alternative would be to make this not a transparent
optimization, but a separate API: ioremap_hugepage() or so.
The devices and drivers dealing with GBs of remapped pages
is still relatively low, so they could make explicit use of
the API and opt in to it.
What I was arguing against was to make it a CONFIG_ option:
that achieves very little in practice, such APIs should be
uniformly available.
Thanks,
Ingo
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next prev parent reply other threads:[~2015-02-24 8:09 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-09 22:45 [PATCH v2 0/7] Kernel huge I/O mapping support Toshi Kani
2015-02-09 22:45 ` [PATCH v2 1/7] mm: Change __get_vm_area_node() to use fls_long() Toshi Kani
2015-02-09 22:45 ` [PATCH v2 2/7] lib: Add huge I/O map capability interfaces Toshi Kani
2015-02-09 22:45 ` [PATCH v2 3/7] mm: Change ioremap to set up huge I/O mappings Toshi Kani
2015-02-09 22:45 ` [PATCH v2 4/7] mm: Change vunmap to tear down huge KVA mappings Toshi Kani
2015-02-09 22:45 ` [PATCH v2 5/7] x86, mm: Support huge KVA mappings on x86 Toshi Kani
2015-02-10 18:59 ` Dave Hansen
2015-02-10 20:42 ` Toshi Kani
2015-02-10 20:51 ` Dave Hansen
2015-02-10 22:13 ` Toshi Kani
2015-02-10 22:20 ` Toshi Kani
2015-02-10 23:10 ` Toshi Kani
2015-03-03 0:37 ` Toshi Kani
2015-02-09 22:45 ` [PATCH v2 6/7] x86, mm: Support huge I/O " Toshi Kani
2015-02-18 20:44 ` Ingo Molnar
2015-02-18 21:13 ` Toshi Kani
2015-02-18 21:15 ` Ingo Molnar
2015-02-18 21:33 ` Toshi Kani
2015-02-18 21:57 ` Ingo Molnar
2015-02-18 22:14 ` Toshi Kani
2015-02-09 22:45 ` [PATCH v2 7/7] mm: Add config HUGE_IOMAP to enable huge I/O mappings Toshi Kani
2015-02-23 20:22 ` [PATCH v2 0/7] Kernel huge I/O mapping support Andrew Morton
2015-02-23 23:54 ` Toshi Kani
2015-02-24 8:09 ` Ingo Molnar [this message]
2015-03-02 15:51 ` Toshi Kani
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