linux-kernel - [PATCH] mips: cma: Do not reserve memory if not required

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Date:	Tue, 28 Oct 2014 11:28:34 +0000
From:	Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>
To:	<ralf@...ux-mips.org>, <Zubair.Kakakhel@...tec.com>
CC:	<linux-mips@...ux-mips.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] mips: cma: Do not reserve memory if not required

Even if CMA is disabled, the for_each_memblock macro expands
to run reserve_bootmem once. Hence, reserve_bootmem attempts to
reserve location 0 of size 0.

Add a check to avoid that.

Issue was highlighted during testing with EVA enabled.
resrve_bootmem used to exit gracefully when passed arguments to
reserve 0 size location at 0 without EVA.

But with EVA enabled, macros would point to different addresses
and the code would trigger a BUG.

Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>
Tested-by: Markos Chandras <markos.chandras@...tec.com>
---
 arch/mips/kernel/setup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 938f157..eacfd7d 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -683,7 +683,8 @@ static void __init arch_mem_init(char **cmdline_p)
 	dma_contiguous_reserve(PFN_PHYS(max_low_pfn));
 	/* Tell bootmem about cma reserved memblock section */
 	for_each_memblock(reserved, reg)
-		reserve_bootmem(reg->base, reg->size, BOOTMEM_DEFAULT);
+		if (reg->size != 0)
+			reserve_bootmem(reg->base, reg->size, BOOTMEM_DEFAULT);
 }
 
 static void __init resource_init(void)
-- 
1.9.1

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