From: Yinghai Lu <yinghai@kernel.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
Russell King <linux@arm.linux.org.uk>,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH/v2] mm/memblock: Properly handle overlaps and fix error path
Date: Wed, 09 Mar 2011 12:41:04 -0800 [thread overview]
Message-ID: <4D77E5E0.6010706@kernel.org> (raw)
In-Reply-To: <1299466980.8833.973.camel@pasglop>
On 03/06/2011 07:03 PM, Benjamin Herrenschmidt wrote:
> Currently memblock_reserve() or memblock_free() don't handle overlaps
> of any kind. There is some special casing for coalescing exactly
> adjacent regions but that's about it.
>
> This is annoying because typically memblock_reserve() is used to
> mark regions passed by the firmware as reserved and we all know
> how much we can trust our firmwares...
>
> Also, with the current code, if we do something it doesn't handle
> right such as trying to memblock_reserve() a large range spanning
> multiple existing smaller reserved regions for example, or doing
> overlapping reservations, it can silently corrupt the internal
> region array, causing odd errors much later on, such as allocations
> returning reserved regions etc...
>
> This patch rewrites the underlying functions that add or remove a
> region to the arrays. The new code is a lot more robust as it fully
> handles overlapping regions. It's also, imho, simpler than the previous
> implementation.
>
> In addition, while doing so, I found a bug where if we fail to double
> the array while adding a region, we would remove the last region of
> the array rather than the region we just allocated. This fixes it too.
>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
>
> Hopefully not damaged with a spurious bit of email header this
> time around... sorry about that.
works on my setups...
[ 0.000000] Subtract (26 early reservations)
[ 0.000000] [000009a000-000009efff]
[ 0.000000] [000009f400-00000fffff]
[ 0.000000] [0001000000-0003495048]
...
before:
[ 0.000000] Subtract (27 early reservations)
[ 0.000000] [000009a000-000009efff]
[ 0.000000] [000009f400-00000fffff]
[ 0.000000] [00000f85b0-00000f86b3]
[ 0.000000] [0001000000-0003495048]
Acked-by: Yinghai Lu <yinghai@kernel.org>
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next prev parent reply other threads:[~2011-03-09 20:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-07 3:03 [PATCH/v2] mm/memblock: Properly handle overlaps and fix error path Benjamin Herrenschmidt
2011-03-09 20:41 ` Yinghai Lu [this message]
2011-03-09 21:20 ` Benjamin Herrenschmidt
2011-03-10 6:46 ` Ingo Molnar
2011-03-10 6:53 ` Benjamin Herrenschmidt
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