[PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled

[PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled

[Kevin Cernekee]

From: Michael Sundius <msundius@cisco.com>

Fix 3 problems in the MIPS SPARSEMEM implementation:

1) mem_init() sets/clears PG_reserved on all pages in the HIGHMEM range
without checking to see whether the page descriptor actually exists.

2) bootmem_init() never calls memory_present() on HIGHMEM pages, so
page descriptors are never created for them if SPARSEMEM is enabled.

3) bootmem_init() calls memory_present() on lowmem pages before bootmem
is fully set up.  This is bad because memory_present() can allocate
bootmem in some circumstances (e.g. if SPARSEMEM_EXTREME ever got
enabled).

Signed-off-by: Michael Sundius <msundius@cisco.com>
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: stable@kernel.org
---
 arch/mips/kernel/setup.c |   18 +++++++++++++++++-
 arch/mips/mm/init.c      |    3 +++
 2 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 8ad1d56..1f9f902 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -390,7 +390,6 @@ static void __init bootmem_init(void)
 
 		/* Register lowmem ranges */
 		free_bootmem(PFN_PHYS(start), size << PAGE_SHIFT);
-		memory_present(0, start, end);
 	}
 
 	/*
@@ -402,6 +401,23 @@ static void __init bootmem_init(void)
 	 * Reserve initrd memory if needed.
 	 */
 	finalize_initrd();
+
+	/*
+	 * Call memory_present() on all valid ranges, for SPARSEMEM.
+	 * This must be done after setting up bootmem, since memory_present()
+	 * may allocate bootmem.
+	 */
+	for (i = 0; i < boot_mem_map.nr_map; i++) {
+		unsigned long start, end;
+
+		if (boot_mem_map.map[i].type != BOOT_MEM_RAM)
+			continue;
+
+		start = PFN_UP(boot_mem_map.map[i].addr);
+		end   = PFN_DOWN(boot_mem_map.map[i].addr
+				    + boot_mem_map.map[i].size);
+		memory_present(0, start, end);
+	}
 }
 
 #endif	/* CONFIG_SGI_IP27 */
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 279599e..78a4cf2 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -392,6 +392,9 @@ void __init mem_init(void)
 	for (tmp = highstart_pfn; tmp < highend_pfn; tmp++) {
 		struct page *page = pfn_to_page(tmp);
 
+		if (!pfn_valid(tmp))
+			continue;
+
 		if (!page_is_ram(tmp)) {
 			SetPageReserved(page);
 			continue;
-- 
1.7.4.2

[PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled

[Kevin Cernekee]

From: Michael Sundius <msundius@cisco.com>

Fix 3 problems in the MIPS SPARSEMEM implementation:

1) mem_init() sets/clears PG_reserved on all pages in the HIGHMEM range
without checking to see whether the page descriptor actually exists.

2) bootmem_init() never calls memory_present() on HIGHMEM pages, so
page descriptors are never created for them if SPARSEMEM is enabled.

3) bootmem_init() calls memory_present() on lowmem pages before bootmem
is fully set up.  This is bad because memory_present() can allocate
bootmem in some circumstances (e.g. if SPARSEMEM_EXTREME ever got
enabled).

Signed-off-by: Michael Sundius <msundius@cisco.com>
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: stable@kernel.org
---
 arch/mips/kernel/setup.c |   18 +++++++++++++++++-
 arch/mips/mm/init.c      |    3 +++
 2 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 8ad1d56..1f9f902 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -390,7 +390,6 @@ static void __init bootmem_init(void)
 
 		/* Register lowmem ranges */
 		free_bootmem(PFN_PHYS(start), size << PAGE_SHIFT);
-		memory_present(0, start, end);
 	}
 
 	/*
@@ -402,6 +401,23 @@ static void __init bootmem_init(void)
 	 * Reserve initrd memory if needed.
 	 */
 	finalize_initrd();
+
+	/*
+	 * Call memory_present() on all valid ranges, for SPARSEMEM.
+	 * This must be done after setting up bootmem, since memory_present()
+	 * may allocate bootmem.
+	 */
+	for (i = 0; i < boot_mem_map.nr_map; i++) {
+		unsigned long start, end;
+
+		if (boot_mem_map.map[i].type != BOOT_MEM_RAM)
+			continue;
+
+		start = PFN_UP(boot_mem_map.map[i].addr);
+		end   = PFN_DOWN(boot_mem_map.map[i].addr
+				    + boot_mem_map.map[i].size);
+		memory_present(0, start, end);
+	}
 }
 
 #endif	/* CONFIG_SGI_IP27 */
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 279599e..78a4cf2 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -392,6 +392,9 @@ void __init mem_init(void)
 	for (tmp = highstart_pfn; tmp < highend_pfn; tmp++) {
 		struct page *page = pfn_to_page(tmp);
 
+		if (!pfn_valid(tmp))
+			continue;
+
 		if (!page_is_ram(tmp)) {
 			SetPageReserved(page);
 			continue;
-- 
1.7.4.2

Re: [PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled

[David Daney]

On 03/31/2011 05:27 PM, Kevin Cernekee wrote:
> From: Michael Sundius<msundius@cisco.com>
>
> Fix 3 problems in the MIPS SPARSEMEM implementation:
>
> 1) mem_init() sets/clears PG_reserved on all pages in the HIGHMEM range
> without checking to see whether the page descriptor actually exists.
>
> 2) bootmem_init() never calls memory_present() on HIGHMEM pages, so
> page descriptors are never created for them if SPARSEMEM is enabled.
>
> 3) bootmem_init() calls memory_present() on lowmem pages before bootmem
> is fully set up.  This is bad because memory_present() can allocate
> bootmem in some circumstances (e.g. if SPARSEMEM_EXTREME ever got
> enabled).
>


I think this may do the same thing as my patch:

http://patchwork.linux-mips.org/patch/1988/

Although my patch had different motivations, and changes some other 
things around too.

David Daney


> Signed-off-by: Michael Sundius<msundius@cisco.com>
> Signed-off-by: Kevin Cernekee<cernekee@gmail.com>
> Cc: stable@kernel.org
> ---
>   arch/mips/kernel/setup.c |   18 +++++++++++++++++-
>   arch/mips/mm/init.c      |    3 +++
>   2 files changed, 20 insertions(+), 1 deletions(-)
>
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index 8ad1d56..1f9f902 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -390,7 +390,6 @@ static void __init bootmem_init(void)
>
>   		/* Register lowmem ranges */
>   		free_bootmem(PFN_PHYS(start), size<<  PAGE_SHIFT);
> -		memory_present(0, start, end);
>   	}
>
>   	/*
> @@ -402,6 +401,23 @@ static void __init bootmem_init(void)
>   	 * Reserve initrd memory if needed.
>   	 */
>   	finalize_initrd();
> +
> +	/*
> +	 * Call memory_present() on all valid ranges, for SPARSEMEM.
> +	 * This must be done after setting up bootmem, since memory_present()
> +	 * may allocate bootmem.
> +	 */
> +	for (i = 0; i<  boot_mem_map.nr_map; i++) {
> +		unsigned long start, end;
> +
> +		if (boot_mem_map.map[i].type != BOOT_MEM_RAM)
> +			continue;
> +
> +		start = PFN_UP(boot_mem_map.map[i].addr);
> +		end   = PFN_DOWN(boot_mem_map.map[i].addr
> +				    + boot_mem_map.map[i].size);
> +		memory_present(0, start, end);
> +	}
>   }
>
>   #endif	/* CONFIG_SGI_IP27 */
> diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
> index 279599e..78a4cf2 100644
> --- a/arch/mips/mm/init.c
> +++ b/arch/mips/mm/init.c
> @@ -392,6 +392,9 @@ void __init mem_init(void)
>   	for (tmp = highstart_pfn; tmp<  highend_pfn; tmp++) {
>   		struct page *page = pfn_to_page(tmp);
>
> +		if (!pfn_valid(tmp))
> +			continue;
> +
>   		if (!page_is_ram(tmp)) {
>   			SetPageReserved(page);
>   			continue;

Re: [PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled

[Kevin Cernekee]

On Fri, Apr 1, 2011 at 9:56 AM, David Daney <ddaney@caviumnetworks.com> wrote:
> I think this may do the same thing as my patch:
>
> http://patchwork.linux-mips.org/patch/1988/
>
> Although my patch had different motivations, and changes some other things
> around too.

I noticed that some of the other architectures have started using the
<linux/memblock.h> APIs for memory setup.  Do you think this would be
useful on MIPS, as part of a larger refactoring of bootmem_init() ?

What I liked about Michael's fix was that it is simple and
straightforward enough to meet the stable tree criteria.  Long term it
would probably be a good idea to clean up the memory init code and get
rid of the cut&paste "for" loops.

Re: [PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled

[Michael Sundius]

David Daney wrote:
>
>
> I think this may do the same thing as my patch:
>
> http://patchwork.linux-mips.org/patch/1988/
>
> Although my patch had different motivations, and changes some other 
> things around too.
>
> David Daney
>
I'm not really sure why your kernel or initrd would be in memory was not 
within
the range that had been accounted for.  are you saying its in high mem?

Re: [PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM enabled

[David Daney]

On 04/01/2011 11:41 AM, Michael Sundius wrote:
> David Daney wrote:
>>
>>
>> I think this may do the same thing as my patch:
>>
>> http://patchwork.linux-mips.org/patch/1988/
>>
>> Although my patch had different motivations, and changes some other
>> things around too.
>>
>> David Daney
>>
> I'm not really sure why your kernel or initrd would be in memory was not
> within
> the range that had been accounted for. are you saying its in high mem?
>

Well the memory initialization code has a bunch of weird rules built in 
that prevent some memory from being used.

For example if the kernel resides in a different SPARSE page than the 
rest of memory bad things happen because memory_present() was not called 
on something that is later freed (when init memory is released).

If I try to put an initrd at a high physical address, the memory below 
that is not usable.

My three patches try to make some sense out of the whole thing.

David Daney