Hi Laura,
On Tue, Nov 12, 2013 at 8:26 AM, Laura Abbott <lauraa@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
> Signed-off-by: Neeti Desai <neetid@xxxxxxxxxxxxxx>
> ---
> 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?
> +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_"
Thank you,
Kyungimn Park
> +int is_vmalloc_addr(const void *x)
> +{
> + struct rb_node *n;
> + struct vmap_area *va;
> + int ret = 0;
> +
> + spin_lock(&vmap_area_lock);
> +
> + for (n = rb_first(vmap_area_root); n; rb_next(n)) {
> + va = rb_entry(n, struct vmap_area, rb_node);
> + if (x >= va->va_start && x < va->va_end) {
> + ret = 1;
> + break;
> + }
> + }
> +
> + spin_unlock(&vmap_area_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL(is_vmalloc_addr);
> +#endif
> +
> int is_vmalloc_or_module_addr(const void *x)
> {
> /*
> @@ -2628,6 +2651,9 @@ static int s_show(struct seq_file *m, void *p)
> if (v->flags & VM_VPAGES)
> seq_printf(m, " vpages");
>
> + if (v->flags & VM_LOWMEM)
> + seq_printf(m, " lowmem");
> +
> show_numa_info(m, v);
> seq_putc(m, '\n');
> return 0;
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> hosted by The Linux Foundation
>
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