Re: [PATCH] mm: free reserved area's memmap if possiable

From: Will Deacon
Date: Mon Feb 13 2017 - 07:18:23 EST

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In reply to: zhouxianrong: "[PATCH] mm: free reserved area's memmap if possiable"
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Adding linux-arm-kernel and devicetree (look for "raw-pfn"), since this
impacts directly on those.

On Mon, Feb 13, 2017 at 08:02:29PM +0800, zhouxianrong@xxxxxxxxxx wrote:
> From: zhouxianrong <zhouxianrong@xxxxxxxxxx>
>
> just like freeing no-map area's memmap we could free reserved
> area's memmap as well only when user of reserved area indicate
> that we can do this in dts or drivers. that is, user of reserved
> area know how to use the reserved area who could not memblock_free
> or free_reserved_xxx the reserved area and regard the area as raw
> pfn usage. the patch supply a way to users who want to utilize the
> memmap memory corresponding to raw pfn reserved areas as many as
> possible.

I don't really understand this. Can you point me at a specific use-case,
please? Is CMA involved here?

Will

(entire patch follows, for the benefit of the extra CCs)

> Signed-off-by: zhouxianrong <zhouxianrong@xxxxxxxxxx>
> ---
> arch/arm64/mm/init.c | 14 +++++++++++++-
> drivers/of/fdt.c | 31 +++++++++++++++++++++++--------
> drivers/of/of_reserved_mem.c | 21 ++++++++++++++-------
> include/linux/memblock.h | 3 +++
> include/linux/of_fdt.h | 2 +-
> mm/memblock.c | 24 ++++++++++++++++++++++++
> 6 files changed, 78 insertions(+), 17 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 380ebe7..7e62ef8 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -358,7 +358,7 @@ static inline void free_memmap(unsigned long start_pfn, unsigned long end_pfn)
> */
> static void __init free_unused_memmap(void)
> {
> - unsigned long start, prev_end = 0;
> + unsigned long start, end, prev_end = 0;
> struct memblock_region *reg;
>
> for_each_memblock(memory, reg) {
> @@ -391,6 +391,18 @@ static void __init free_unused_memmap(void)
> if (!IS_ALIGNED(prev_end, PAGES_PER_SECTION))
> free_memmap(prev_end, ALIGN(prev_end, PAGES_PER_SECTION));
> #endif
> +
> + for_each_memblock(reserved, reg) {
> + if (!(reg->flags & MEMBLOCK_RAW_PFN))
> + continue;
> +
> + start = memblock_region_memory_base_pfn(reg);
> + end = round_down(memblock_region_memory_end_pfn(reg),
> + MAX_ORDER_NR_PAGES);
> +
> + if (start < end)
> + free_memmap(start, end);
> + }
> }
> #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index c9b5cac..39e7474 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -582,7 +582,7 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> phys_addr_t base, size;
> int len;
> const __be32 *prop;
> - int nomap, first = 1;
> + int nomap, raw_pfn, first = 1;
>
> prop = of_get_flat_dt_prop(node, "reg", &len);
> if (!prop)
> @@ -595,13 +595,15 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> }
>
> nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> + raw_pfn = of_get_flat_dt_prop(node, "raw-pfn", NULL) != NULL;
>
> while (len >= t_len) {
> base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> size = dt_mem_next_cell(dt_root_size_cells, &prop);
>
> if (size &&
> - early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
> + early_init_dt_reserve_memory_arch(base, size, nomap,
> + raw_pfn) == 0)
> pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %ld MiB\n",
> uname, &base, (unsigned long)size / SZ_1M);
> else
> @@ -699,7 +701,7 @@ void __init early_init_fdt_scan_reserved_mem(void)
> fdt_get_mem_rsv(initial_boot_params, n, &base, &size);
> if (!size)
> break;
> - early_init_dt_reserve_memory_arch(base, size, 0);
> + early_init_dt_reserve_memory_arch(base, size, 0, 0);
> }
>
> of_scan_flat_dt(__fdt_scan_reserved_mem, NULL);
> @@ -717,6 +719,7 @@ void __init early_init_fdt_reserve_self(void)
> /* Reserve the dtb region */
> early_init_dt_reserve_memory_arch(__pa(initial_boot_params),
> fdt_totalsize(initial_boot_params),
> + 0,
> 0);
> }
>
> @@ -1161,11 +1164,21 @@ int __init __weak early_init_dt_mark_hotplug_memory_arch(u64 base, u64 size)
> }
>
> int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
> - phys_addr_t size, bool nomap)
> + phys_addr_t size, bool nomap,
> + bool raw_pfn)
> {
> + int err;
> +
> if (nomap)
> return memblock_remove(base, size);
> - return memblock_reserve(base, size);
> +
> + err = memblock_reserve(base, size);
> + if (err == 0) {
> + if (raw_pfn)
> + memblock_mark_raw_pfn(base, size);
> + }
> +
> + return err;
> }
>
> /*
> @@ -1188,10 +1201,12 @@ int __init __weak early_init_dt_mark_hotplug_memory_arch(u64 base, u64 size)
> }
>
> int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
> - phys_addr_t size, bool nomap)
> + phys_addr_t size, bool nomap,
> + bool raw_pfn)
> {
> - pr_err("Reserved memory not supported, ignoring range %pa - %pa%s\n",
> - &base, &size, nomap ? " (nomap)" : "");
> + pr_err("Reserved memory not supported, ignoring range %pa - %pa%s - %pa%s\n",
> + &base, &size, nomap ? " (nomap)" : "",
> + raw_pfn ? " (raw-pfn)" : "");
> return -ENOSYS;
> }
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 366d8c3..d7d9255 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -33,7 +33,7 @@
> #include <linux/memblock.h>
> int __init __weak early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> phys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,
> - phys_addr_t *res_base)
> + bool raw_pfn, phys_addr_t *res_base)
> {
> phys_addr_t base;
> /*
> @@ -56,15 +56,19 @@ int __init __weak early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> *res_base = base;
> if (nomap)
> return memblock_remove(base, size);
> +
> + if (raw_pfn)
> + memblock_mark_raw_pfn(base, size);
> +
> return 0;
> }
> #else
> int __init __weak early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> phys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,
> - phys_addr_t *res_base)
> + bool raw_pfn, phys_addr_t *res_base)
> {
> - pr_err("Reserved memory not supported, ignoring region 0x%llx%s\n",
> - size, nomap ? " (nomap)" : "");
> + pr_err("Reserved memory not supported, ignoring region 0x%llx%s 0x%llx%s\n",
> + size, nomap ? " (nomap)" : "", raw_pfn ? " (raw-pfn)" : "");
> return -ENOSYS;
> }
> #endif
> @@ -103,7 +107,7 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
> phys_addr_t base = 0, align = 0, size;
> int len;
> const __be32 *prop;
> - int nomap;
> + int nomap, raw_pfn;
> int ret;
>
> prop = of_get_flat_dt_prop(node, "size", &len);
> @@ -117,6 +121,7 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
> size = dt_mem_next_cell(dt_root_size_cells, &prop);
>
> nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> + raw_pfn = of_get_flat_dt_prop(node, "raw-pfn", NULL) != NULL;
>
> prop = of_get_flat_dt_prop(node, "alignment", &len);
> if (prop) {
> @@ -156,7 +161,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
> &prop);
>
> ret = early_init_dt_alloc_reserved_memory_arch(size,
> - align, start, end, nomap, &base);
> + align, start, end, nomap,
> + raw_pfn, &base);
> if (ret == 0) {
> pr_debug("allocated memory for '%s' node: base %pa, size %ld MiB\n",
> uname, &base,
> @@ -168,7 +174,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
>
> } else {
> ret = early_init_dt_alloc_reserved_memory_arch(size, align,
> - 0, 0, nomap, &base);
> + 0, 0, nomap,
> + raw_pfn, &base);
> if (ret == 0)
> pr_debug("allocated memory for '%s' node: base %pa, size %ld MiB\n",
> uname, &base, (unsigned long)size / SZ_1M);
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 5b759c9..7266be1 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -26,6 +26,7 @@ enum {
> MEMBLOCK_HOTPLUG = 0x1, /* hotpluggable region */
> MEMBLOCK_MIRROR = 0x2, /* mirrored region */
> MEMBLOCK_NOMAP = 0x4, /* don't add to kernel direct mapping */
> + MEMBLOCK_RAW_PFN = 0x8, /* raw pfn region's memmap never used */
> };
>
> struct memblock_region {
> @@ -92,6 +93,8 @@ bool memblock_overlaps_region(struct memblock_type *type,
> int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
> int memblock_mark_mirror(phys_addr_t base, phys_addr_t size);
> int memblock_mark_nomap(phys_addr_t base, phys_addr_t size);
> +int memblock_mark_raw_pfn(phys_addr_t base, phys_addr_t size);
> +int memblock_clear_raw_pfn(phys_addr_t base, phys_addr_t size);
> ulong choose_memblock_flags(void);
>
> /* Low level functions */
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index 271b3fd..29284d7 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -73,7 +73,7 @@ extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
> extern void early_init_dt_add_memory_arch(u64 base, u64 size);
> extern int early_init_dt_mark_hotplug_memory_arch(u64 base, u64 size);
> extern int early_init_dt_reserve_memory_arch(phys_addr_t base, phys_addr_t size,
> - bool no_map);
> + bool no_map, bool raw_pfn);
> extern void * early_init_dt_alloc_memory_arch(u64 size, u64 align);
> extern u64 dt_mem_next_cell(int s, const __be32 **cellp);
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 7608bc3..c103b94 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -814,6 +814,30 @@ int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size)
> }
>
> /**
> + * memblock_mark_raw_pfn - Mark raw pfn memory with flag MEMBLOCK_RAW_PFN.
> + * @base: the base phys addr of the region
> + * @size: the size of the region
> + *
> + * Return 0 on succees, -errno on failure.
> + */
> +int __init_memblock memblock_mark_raw_pfn(phys_addr_t base, phys_addr_t size)
> +{
> + return memblock_setclr_flag(base, size, 1, MEMBLOCK_RAW_PFN);
> +}
> +
> +/**
> + * memblock_clear_raw_pfn - Clear flag MEMBLOCK_RAW_PFN for a specified region.
> + * @base: the base phys addr of the region
> + * @size: the size of the region
> + *
> + * Return 0 on succees, -errno on failure.
> + */
> +int __init_memblock memblock_clear_raw_pfn(phys_addr_t base, phys_addr_t size)
> +{
> + return memblock_setclr_flag(base, size, 0, MEMBLOCK_RAW_PFN);
> +}
> +
> +/**
> * __next_reserved_mem_region - next function for for_each_reserved_region()
> * @idx: pointer to u64 loop variable
> * @out_start: ptr to phys_addr_t for start address of the region, can be %NULL
> --
> 1.7.9.5
>

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In reply to: zhouxianrong: "[PATCH] mm: free reserved area's memmap if possiable"
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