Re: [PATCH v2 4/6] mm/memory_hotplug: Rename walk_memory_range() and pass start+size instead of pfns

Nathan Chancellor
2019-06-20T16:05:14Z

On Thu, Jun 20, 2019 at 12:35:18PM +0200, David Hildenbrand wrote:
> walk_memory_range() was once used to iterate over sections. Now, it
> iterates over memory blocks. Rename the function, fixup the
> documentation. Also, pass start+size instead of PFNs, which is what most
> callers already have at hand. (we'll rework link_mem_sections() most
> probably soon)
>
> Follow-up patches wil rework, simplify, and move walk_memory_blocks() to
> drivers/base/memory.c.
>
> Note: walk_memory_blocks() only works correctly right now if the
> start_pfn is aligned to a section start. This is the case right now,
> but we'll generalize the function in a follow up patch so the semantics
> match the documentation.
>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Len Brown <lenb@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Rashmica Gupta <rashmica.g@gmail.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Michael Neuling <mikey@neuling.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Qian Cai <cai@lca.pw>
> Cc: Arun KS <arunks@codeaurora.org>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> arch/powerpc/platforms/powernv/memtrace.c | 22 ++++++++++-----------
> drivers/acpi/acpi_memhotplug.c | 19 ++++--------------
> drivers/base/node.c | 5 +++--
> include/linux/memory_hotplug.h | 2 +-
> mm/memory_hotplug.c | 24 ++++++++++++-----------
> 5 files changed, 32 insertions(+), 40 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c
> index 5e53c1392d3b..8c82c041afe6 100644
> --- a/arch/powerpc/platforms/powernv/memtrace.c
> +++ b/arch/powerpc/platforms/powernv/memtrace.c
> @@ -70,23 +70,24 @@ static int change_memblock_state(struct memory_block *mem, void *arg)
> /* called with device_hotplug_lock held */
> static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
> {
> + const unsigned long start = PFN_PHYS(start_pfn);
> + const unsigned long size = PFN_PHYS(nr_pages);
> u64 end_pfn = start_pfn + nr_pages - 1;

This variable should be removed:

arch/powerpc/platforms/powernv/memtrace.c:75:6: warning: unused variable 'end_pfn' [-Wunused-variable]
u64 end_pfn = start_pfn + nr_pages - 1;
^
1 warning generated.

https://travis-ci.com/ClangBuiltLinux/continuous-integration/jobs/209576737

Cheers,
Nathan

>
> - if (walk_memory_range(start_pfn, end_pfn, NULL,
> - check_memblock_online))
> + if (walk_memory_blocks(start, size, NULL, check_memblock_online))
> return false;
>
> - walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
> - change_memblock_state);
> + walk_memory_blocks(start, size, (void *)MEM_GOING_OFFLINE,
> + change_memblock_state);
>
> if (offline_pages(start_pfn, nr_pages)) {
> - walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
> - change_memblock_state);
> + walk_memory_blocks(start, size, (void *)MEM_ONLINE,
> + change_memblock_state);
> return false;
> }
>
> - walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
> - change_memblock_state);
> + walk_memory_blocks(start, size, (void *)MEM_OFFLINE,
> + change_memblock_state);
>
>
> return true;
> @@ -242,9 +243,8 @@ static int memtrace_online(void)
> */
> if (!memhp_auto_online) {
> lock_device_hotplug();
> - walk_memory_range(PFN_DOWN(ent->start),
> - PFN_UP(ent->start + ent->size - 1),
> - NULL, online_mem_block);
> + walk_memory_blocks(ent->start, ent->size, NULL,
> + online_mem_block);
> unlock_device_hotplug();
> }
>
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index db013dc21c02..e294f44a7850 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -155,16 +155,6 @@ static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
> return 0;
> }
>
> -static unsigned long acpi_meminfo_start_pfn(struct acpi_memory_info *info)
> -{
> - return PFN_DOWN(info->start_addr);
> -}
> -
> -static unsigned long acpi_meminfo_end_pfn(struct acpi_memory_info *info)
> -{
> - return PFN_UP(info->start_addr + info->length-1);
> -}
> -
> static int acpi_bind_memblk(struct memory_block *mem, void *arg)
> {
> return acpi_bind_one(&mem->dev, arg);
> @@ -173,9 +163,8 @@ static int acpi_bind_memblk(struct memory_block *mem, void *arg)
> static int acpi_bind_memory_blocks(struct acpi_memory_info *info,
> struct acpi_device *adev)
> {
> - return walk_memory_range(acpi_meminfo_start_pfn(info),
> - acpi_meminfo_end_pfn(info), adev,
> - acpi_bind_memblk);
> + return walk_memory_blocks(info->start_addr, info->length, adev,
> + acpi_bind_memblk);
> }
>
> static int acpi_unbind_memblk(struct memory_block *mem, void *arg)
> @@ -186,8 +175,8 @@ static int acpi_unbind_memblk(struct memory_block *mem, void *arg)
>
> static void acpi_unbind_memory_blocks(struct acpi_memory_info *info)
> {
> - walk_memory_range(acpi_meminfo_start_pfn(info),
> - acpi_meminfo_end_pfn(info), NULL, acpi_unbind_memblk);
> + walk_memory_blocks(info->start_addr, info->length, NULL,
> + acpi_unbind_memblk);
> }
>
> static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index e6364e3e3e31..d8c02e65df68 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -833,8 +833,9 @@ void unregister_memory_block_under_nodes(struct memory_block *mem_blk)
>
> int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn)
> {
> - return walk_memory_range(start_pfn, end_pfn, (void *)&nid,
> - register_mem_sect_under_node);
> + return walk_memory_blocks(PFN_PHYS(start_pfn),
> + PFN_PHYS(end_pfn - start_pfn), (void *)&nid,
> + register_mem_sect_under_node);
> }
>
> #ifdef CONFIG_HUGETLBFS
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 79e0add6a597..d9fffc34949f 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -340,7 +340,7 @@ static inline void __remove_memory(int nid, u64 start, u64 size) {}
> #endif /* CONFIG_MEMORY_HOTREMOVE */
>
> extern void __ref free_area_init_core_hotplug(int nid);
> -extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
> +extern int walk_memory_blocks(unsigned long start, unsigned long size,
> void *arg, int (*func)(struct memory_block *, void *));
> extern int __add_memory(int nid, u64 start, u64 size);
> extern int add_memory(int nid, u64 start, u64 size);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index a88c5f334e5a..122a7d31efdd 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1126,8 +1126,7 @@ int __ref add_memory_resource(int nid, struct resource *res)
>
> /* online pages if requested */
> if (memhp_auto_online)
> - walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1),
> - NULL, online_memory_block);
> + walk_memory_blocks(start, size, NULL, online_memory_block);
>
> return ret;
> error:
> @@ -1665,20 +1664,24 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
> #endif /* CONFIG_MEMORY_HOTREMOVE */
>
> /**
> - * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
> - * @start_pfn: start pfn of the memory range
> - * @end_pfn: end pfn of the memory range
> + * walk_memory_blocks - walk through all present memory blocks overlapped
> + * by the range [start, start + size)
> + *
> + * @start: start address of the memory range
> + * @size: size of the memory range
> * @arg: argument passed to func
> - * @func: callback for each memory section walked
> + * @func: callback for each memory block walked
> *
> - * This function walks through all present mem sections in range
> - * [start_pfn, end_pfn) and call func on each mem section.
> + * This function walks through all present memory blocks overlapped by the
> + * range [start, start + size), calling func on each memory block.
> *
> * Returns the return value of func.
> */
> -int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
> +int walk_memory_blocks(unsigned long start, unsigned long size,
> void *arg, int (*func)(struct memory_block *, void *))
> {
> + const unsigned long start_pfn = PFN_DOWN(start);
> + const unsigned long end_pfn = PFN_UP(start + size - 1);
> struct memory_block *mem = NULL;
> struct mem_section *section;
> unsigned long pfn, section_nr;
> @@ -1824,8 +1827,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
> * whether all memory blocks in question are offline and return error
> * if this is not the case.
> */
> - rc = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
> - check_memblock_offlined_cb);
> + rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb);
> if (rc)
> goto done;
>
> --
> 2.21.0
>