[RFC PATCH 3/4] mm/vmalloc.c: Allow lowmem to be tracked in vmalloc
Laura Abbott
lauraa at codeaurora.org
Mon Nov 11 20:23:02 EST 2013
On 11/11/2013 3:37 PM, Kyungmin Park wrote:
> Hi Laura,
>
> On Tue, Nov 12, 2013 at 8:26 AM, Laura Abbott <lauraa at codeaurora.org> wrote:
>> vmalloc is currently assumed to be a completely separate address space
>> from the lowmem region. While this may be true in the general case,
>> there are some instances where lowmem and virtual space intermixing
>> provides gains. One example is needing to steal a large chunk of physical
>> lowmem for another purpose outside the systems usage. Rather than
>> waste the precious lowmem space on a 32-bit system, we can allow the
>> virtual holes created by the physical holes to be used by vmalloc
>> for virtual addressing. Track lowmem allocations in vmalloc to
>> allow mixing of lowmem and vmalloc.
>>
>> Signed-off-by: Laura Abbott <lauraa at codeaurora.org>
>> Signed-off-by: Neeti Desai <neetid at codeaurora.org>
>> ---
>> include/linux/mm.h | 6 ++++++
>> include/linux/vmalloc.h | 1 +
>> mm/Kconfig | 11 +++++++++++
>> mm/vmalloc.c | 26 ++++++++++++++++++++++++++
>> 4 files changed, 44 insertions(+), 0 deletions(-)
>>
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index f022460..76df50d 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -308,6 +308,10 @@ unsigned long vmalloc_to_pfn(const void *addr);
>> * On nommu, vmalloc/vfree wrap through kmalloc/kfree directly, so there
>> * is no special casing required.
>> */
>> +
>> +#ifdef CONFIG_VMALLOC_SAVING
> mismatch below Kconfig. CONFIG_ENABLE_VMALLOC_SAVING?
Argh, I folded in a wrong patch when integrating. I'll fix it.
>> +extern int is_vmalloc_addr(const void *x)
>> +#else
>> static inline int is_vmalloc_addr(const void *x)
>> {
>> #ifdef CONFIG_MMU
>> @@ -318,6 +322,8 @@ static inline int is_vmalloc_addr(const void *x)
>> return 0;
>> #endif
>> }
>> +#endif
>> +
>> #ifdef CONFIG_MMU
>> extern int is_vmalloc_or_module_addr(const void *x);
>> #else
>> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
>> index 4b8a891..e0c8c49 100644
>> --- a/include/linux/vmalloc.h
>> +++ b/include/linux/vmalloc.h
>> @@ -16,6 +16,7 @@ struct vm_area_struct; /* vma defining user mapping in mm_types.h */
>> #define VM_USERMAP 0x00000008 /* suitable for remap_vmalloc_range */
>> #define VM_VPAGES 0x00000010 /* buffer for pages was vmalloc'ed */
>> #define VM_UNINITIALIZED 0x00000020 /* vm_struct is not fully initialized */
>> +#define VM_LOWMEM 0x00000040 /* Tracking of direct mapped lowmem */
>> /* bits [20..32] reserved for arch specific ioremap internals */
>>
>> /*
>> diff --git a/mm/Kconfig b/mm/Kconfig
>> index 8028dcc..b3c459d 100644
>> --- a/mm/Kconfig
>> +++ b/mm/Kconfig
>> @@ -519,3 +519,14 @@ config MEM_SOFT_DIRTY
>> it can be cleared by hands.
>>
>> See Documentation/vm/soft-dirty.txt for more details.
>> +
>> +config ENABLE_VMALLOC_SAVING
>> + bool "Intermix lowmem and vmalloc virtual space"
>> + depends on ARCH_TRACKS_VMALLOC
>> + help
>> + Some memory layouts on embedded systems steal large amounts
>> + of lowmem physical memory for purposes outside of the kernel.
>> + Rather than waste the physical and virtual space, allow the
>> + kernel to use the virtual space as vmalloc space.
>> +
>> + If unsure, say N.
>> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
>> index 13a5495..c7b138b 100644
>> --- a/mm/vmalloc.c
>> +++ b/mm/vmalloc.c
>> @@ -204,6 +204,29 @@ static int vmap_page_range(unsigned long start, unsigned long end,
>> return ret;
>> }
>>
>> +#ifdef ENABLE_VMALLOC_SAVING
> missing "CONFIG_"
>
Yes, this is a mess and needs to be cleaned up.
> Thank you,
> Kyungimn Park
Thanks,
Laura
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation
More information about the linux-arm-kernel
mailing list