Re: [PATCHv4 2/2] arm: Get rid of meminfo

[Grygorii Strashko <grygorii.strashko@ti.com>]

On 03/12/2014 03:38 PM, Russell King - ARM Linux wrote:
> On Wed, Mar 12, 2014 at 03:09:53PM +0200, Grygorii Strashko wrote:
>> Hi Russell,
>>
>> On 03/12/2014 10:54 AM, Russell King - ARM Linux wrote:
>>> On Tue, Feb 18, 2014 at 02:15:33PM -0800, Laura Abbott wrote:
>>>> memblock is now fully integrated into the kernel and is the prefered
>>>> method for tracking memory. Rather than reinvent the wheel with
>>>> meminfo, migrate to using memblock directly instead of meminfo as
>>>> an intermediate.
>>>>
>>>> Acked-by: Jason Cooper <jason@lakedaemon.net>
>>>> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
>>>> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
>>>> Acked-by: Kukjin Kim <kgene.kim@samsung.com>
>>>> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
>>>> Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
>>>> Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
>>>
>>> Laura,
>>>
>>> This patch causes a bunch of platforms to no longer boot - imx6solo with
>>> 1GB of RAM boots, imx6q with 2GB of RAM doesn't.  Versatile Express doesn't.
>>>
>>> The early printk messages don't reveal anything too interesting:
>>>
>>> Booting Linux on physical CPU 0x0
>>> Linux version 3.14.0-rc6+ (rmk@rmk-PC.arm.linux.org.uk) (gcc version 4.6.4 (GCC) ) #630 SMP Wed Mar 12 01:13:36 GMT 2014
>>> CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), cr=10c53c7d
>>> CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
>>> Machine model: SolidRun Cubox-i Dual/Quad
>>> cma: CMA: reserved 64 MiB at 8c000000
>>> Memory policy: Data cache writealloc
>>> <hang>
>>>
>>> vs.
>>>
>>> Booting Linux on physical CPU 0x0
>>> Linux version 3.14.0-rc6+ (rmk@rmk-PC.arm.linux.org.uk) (gcc version 4.6.4 (GCC) ) #631 SMP Wed Mar 12 01:15:37 GMT 2014
>>> CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), cr=10c53c7d
>>> CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
>>> Machine model: SolidRun Cubox-i Dual/Quad
>>> cma: CMA: reserved 64 MiB at 3b800000
>>> Memory policy: Data cache writealloc
>>> On node 0 totalpages: 524288
>>> free_area_init_node: node 0, pgdat c09d0240, node_mem_map ea7d8000
>>>     Normal zone: 1520 pages used for memmap
>>>     Normal zone: 0 pages reserved
>>>     Normal zone: 194560 pages, LIFO batch:31
>>>     HighMem zone: 2576 pages used for memmap
>>>     HighMem zone: 329728 pages, LIFO batch:31
>>> ...
>>>
>>> The only obvious difference is the address of that CMA reservation,
>>> CMA shouldn't make a difference here - but I suspect that other
>>> allocations which need to be in lowmem probably aren't.
>>>
>>
>> Could it be possible to enable memblock debug by adding "memblock=debug"
>> in cmdline?
> 
> Here's with Laura's patch:
> 
> Uncompressing Linux... done, booting the kernel.
> Booting Linux on physical CPU 0x0
> Linux version 3.14.0-rc6+ (rmk@rmk-PC.arm.linux.org.uk) (gcc version 4.6.4 (GCC) ) #633 SMP Wed Mar 12 12:56:15 GMT 2014
> CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), cr=10c53c7d
> CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
> Machine model: SolidRun Cubox-i Dual/Quad
> memblock_reserve: [0x00000010008240-0x0000001112c1f7] flags 0x0 arm_memblock_init+0x28/0x1a8
> memblock_reserve: [0x00000020000040-0x000000201caa57] flags 0x0 arm_memblock_init+0x108/0x1a8
> memblock_reserve: [0x00000010004000-0x00000010007fff] flags 0x0 arm_mm_memblock_reserve+0x1c/0x24
> memblock_reserve: [0x00000018000000-0x0000001800b07f] flags 0x0 arm_dt_memblock_reserve+0x2c/0x70
> memblock_reserve: [0x00000018000000-0x0000001800afff] flags 0x0 arm_dt_memblock_reserve+0x68/0x70
> memblock_reserve: [0x00000020000040-0x000000201caa57] flags 0x0 arm_dt_memblock_reserve+0x68/0x70
> memblock_reserve: [0x0000008c000000-0x0000008fffffff] flags 0x0 memblock_alloc_base_nid+0x40/0x54
> cma: CMA: reserved 64 MiB at 8c000000
> MEMBLOCK configuration:
>   memory size = 0x80000000 reserved size = 0x52fda50
>   memory.cnt  = 0x1
>   memory[0x0]   [0x00000010000000-0x0000008fffffff], 0x80000000 bytes flags: 0x06
>   reserved.cnt  = 0x5
>   reserved[0x0] [0x00000010004000-0x00000010007fff], 0x4000 bytes flags: 0x0
>   reserved[0x1] [0x00000010008240-0x0000001112c1f7], 0x1123fb8 bytes flags: 0x0
>   reserved[0x2] [0x00000018000000-0x0000001800b07f], 0xb080 bytes flags: 0x0
>   reserved[0x3] [0x00000020000040-0x000000201caa57], 0x1caa18 bytes flags: 0x0
>   reserved[0x4] [0x0000008c000000-0x0000008fffffff], 0x4000000 bytes flags: 0x0
> Memory policy: Data cache writealloc
> memblock_reserve: [0x0000008bffffd8-0x0000008bffffff] flags 0x0 memblock_alloc_base_nid+0x40/0x54
> 
> Here's without:
> 
> Booting Linux on physical CPU 0x0
> Linux version 3.14.0-rc6+ (rmk@rmk-PC.arm.linux.org.uk) (gcc version 4.6.4 (GCC) ) #635 SMP Wed Mar 12 13:22:15 GMT 2014
> CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), cr=10c53c7d
> CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
> Machine model: SolidRun Cubox-i Dual/Quad
> memblock_reserve: [0x00000010008240-0x0000001112c277] flags 0x0 arm_memblock_init+0x54/0x1d4
> memblock_reserve: [0x00000020000040-0x000000201caa57] flags 0x0 arm_memblock_init+0x134/0x1d4
> memblock_reserve: [0x00000010004000-0x00000010007fff] flags 0x0 arm_mm_memblock_reserve+0x1c/0x24
> memblock_reserve: [0x00000018000000-0x0000001800b07f] flags 0x0 arm_dt_memblock_reserve+0x2c/0x70
> memblock_reserve: [0x00000018000000-0x0000001800afff] flags 0x0 arm_dt_memblock_reserve+0x68/0x70
> memblock_reserve: [0x00000020000040-0x000000201caa57] flags 0x0 arm_dt_memblock_reserve+0x68/0x70
> memblock_reserve: [0x0000003b800000-0x0000003f7fffff] flags 0x0 memblock_alloc_base_nid+0x40/0x54
> cma: CMA: reserved 64 MiB at 3b800000
> MEMBLOCK configuration:
>   memory size = 0x80000000 reserved size = 0x52fdad0
>   memory.cnt  = 0x1
>   memory[0x0]     [0x00000010000000-0x0000008fffffff], 0x80000000 bytes flags: 0x0
>   reserved.cnt  = 0x5
>   reserved[0x0]   [0x00000010004000-0x00000010007fff], 0x4000 bytes flags: 0x0
>   reserved[0x1]   [0x00000010008240-0x0000001112c277], 0x1124038 bytes flags: 0x0
>   reserved[0x2]   [0x00000018000000-0x0000001800b07f], 0xb080 bytes flags: 0x0
>   reserved[0x3]   [0x00000020000040-0x000000201caa57], 0x1caa18 bytes flags: 0x0
>   reserved[0x4]   [0x0000003b800000-0x0000003f7fffff], 0x4000000 bytes flags: 0x0
> Memory policy: Data cache writealloc
> memblock_reserve: [0x0000003b7fffd8-0x0000003b7fffff] flags 0x0 memblock_alloc_base_nid+0x40/0x54
> memblock_reserve: [0x0000003b7fe000-0x0000003b7fefff] flags 0x0 memblock_alloc_base_nid+0x40/0x54
> memblock_reserve: [0x0000003b7fd000-0x0000003b7fdfff] flags 0x0 memblock_alloc_base_nid+0x40/0x54
> memblock_reserve: [0x0000003b7fc000-0x0000003b7fcfff] flags 0x0 memblock_alloc_base_nid+0x40/0x54
> ...
> 
> So it looks like allocations which must come from lowmem aren't being
> limited to lowmem.
> 
> Try booting a machine with 2G of RAM with page offset set to 3GB and
> highmem enabled - it will fail as per the above.
> 
> In fact, if we look at sanity_check_meminfo() post that patch, it's
> clearly wrong:
> 
>          for_each_memblock(memory, reg) {
>                  phys_addr_t block_start = reg->base;
>                  phys_addr_t block_end = reg->base + reg->size;
>                  phys_addr_t size_limit = reg->size;
> 
>                  if (reg->base >= vmalloc_limit)
>                          highmem = 1;
>                  else
>                          size_limit = vmalloc_limit - reg->base;
> ...
>                  if (!highmem) {
>                          if (block_end > arm_lowmem_limit)
>                                  arm_lowmem_limit = block_end;

In v3, above was 
		arm_lowmem_limit = reg->base + size_limit;

so, it has worked somehow, even arm_lowmem_limit can point on non 
existed address. It was changed because of my comment - sorry.

I think, it should be smth like:
if (!highmem) {
	if (block_end > arm_lowmem_limit)
		if (reg->size > size_limit)
			arm_lowmem_limit = vmalloc_limit;
		else 
			arm_lowmem_limit = block_end;

I've created and attached the patch which allows me to boot on keystone.

> ...
>                  }

regards,
-grygorii

>From 3a210330f15c4cfc6728d83b28750c696d9eaefb Mon Sep 17 00:00:00 2001
From: Grygorii Strashko <x0174654@uglx0174654.(none)>
Date: Wed, 12 Mar 2014 18:04:02 +0200
Subject: [PATCH] arm: get rid of meminfo: fix lowmem_limit calculation

Signed-off-by: Grygorii Strashko <x0174654@uglx0174654.(none)>
---
 arch/arm/mm/mmu.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index c3ae96c..f8b5175 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1096,8 +1096,12 @@ void __init sanity_check_meminfo(void)
 		}
 
 		if (!highmem) {
-			if (block_end > arm_lowmem_limit)
-				arm_lowmem_limit = block_end;
+			if (block_end > arm_lowmem_limit) {
+				if (reg->size > size_limit)
+					arm_lowmem_limit = vmalloc_limit;
+				else
+					arm_lowmem_limit = block_end;
+			}
 
 
 			/*
@@ -1117,7 +1121,7 @@ void __init sanity_check_meminfo(void)
 				if (!IS_ALIGNED(block_start, SECTION_SIZE))
 					memblock_limit = block_start;
 				else if (!IS_ALIGNED(block_end, SECTION_SIZE))
-					memblock_limit = block_end;
+					memblock_limit = arm_lowmem_limit;
 			}
 
 		}
-- 
1.7.9.5

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