On 12/8/20 9:28 AM, Joao Martins wrote:
Replace vmem_altmap with an vmem_context argument. That let us
express how the vmemmap is gonna be initialized e.g. passing
flags and a page size for reusing pages upon initializing the
vmemmap.

How about this instead:

Replace the vmem_altmap argument with a vmem_context argument that
contains vmem_altmap for now. Subsequent patches will add additional
member elements to vmem_context, such as flags and page size.

No behavior changes are intended.

?


Signed-off-by: Joao Martins <[email protected]>
---
  include/linux/memory_hotplug.h |  6 +++++-
  include/linux/mm.h             |  2 +-
  mm/memory_hotplug.c            |  3 ++-
  mm/sparse-vmemmap.c            |  6 +++++-
  mm/sparse.c                    | 16 ++++++++--------
  5 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 551093b74596..73f8bcbb58a4 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -81,6 +81,10 @@ struct mhp_params {
        pgprot_t pgprot;
  };
+struct vmem_context {
+       struct vmem_altmap *altmap;
+};
+
  /*
   * Zone resizing functions
   *
@@ -353,7 +357,7 @@ extern void remove_pfn_range_from_zone(struct zone *zone,
                                       unsigned long nr_pages);
  extern bool is_memblock_offlined(struct memory_block *mem);
  extern int sparse_add_section(int nid, unsigned long pfn,
-               unsigned long nr_pages, struct vmem_altmap *altmap);
+               unsigned long nr_pages, struct vmem_context *ctx);
  extern void sparse_remove_section(struct mem_section *ms,
                unsigned long pfn, unsigned long nr_pages,
                unsigned long map_offset, struct vmem_altmap *altmap);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index db6ae4d3fb4e..2eb44318bb2d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3000,7 +3000,7 @@ static inline void print_vma_addr(char *prefix, unsigned 
long rip)
void *sparse_buffer_alloc(unsigned long size);
  struct page * __populate_section_memmap(unsigned long pfn,
-               unsigned long nr_pages, int nid, struct vmem_altmap *altmap);
+               unsigned long nr_pages, int nid, struct vmem_context *ctx);
  pgd_t *vmemmap_pgd_populate(unsigned long addr, int node);
  p4d_t *vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node);
  pud_t *vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 63b2e46b6555..f8870c53fe5e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -313,6 +313,7 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned 
long nr_pages,
        unsigned long cur_nr_pages;
        int err;
        struct vmem_altmap *altmap = params->altmap;
+       struct vmem_context ctx = { .altmap = params->altmap };

OK, so this is the one place I can see where ctx is set up. And it's never null.
Let's remember that point...

if (WARN_ON_ONCE(!params->pgprot.pgprot))
                return -EINVAL;
@@ -341,7 +342,7 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned 
long nr_pages,
                /* Select all remaining pages up to the next section boundary */
                cur_nr_pages = min(end_pfn - pfn,
                                   SECTION_ALIGN_UP(pfn + 1) - pfn);
-               err = sparse_add_section(nid, pfn, cur_nr_pages, altmap);
+               err = sparse_add_section(nid, pfn, cur_nr_pages, &ctx);
                if (err)
                        break;
                cond_resched();
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 16183d85a7d5..bcda68ba1381 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -249,15 +249,19 @@ int __meminit vmemmap_populate_basepages(unsigned long 
start, unsigned long end,
  }
struct page * __meminit __populate_section_memmap(unsigned long pfn,
-               unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
+               unsigned long nr_pages, int nid, struct vmem_context *ctx)
  {
        unsigned long start = (unsigned long) pfn_to_page(pfn);
        unsigned long end = start + nr_pages * sizeof(struct page);
+       struct vmem_altmap *altmap = NULL;
if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
                !IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
                return NULL;
+ if (ctx)

But...ctx can never be null, right?

I didn't spot any other issues, though.

thanks,
--
John Hubbard
NVIDIA

+               altmap = ctx->altmap;
+
        if (vmemmap_populate(start, end, nid, altmap))
                return NULL;
diff --git a/mm/sparse.c b/mm/sparse.c
index 7bd23f9d6cef..47ca494398a7 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -443,7 +443,7 @@ static unsigned long __init section_map_size(void)
  }
struct page __init *__populate_section_memmap(unsigned long pfn,
-               unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
+               unsigned long nr_pages, int nid, struct vmem_context *ctx)
  {
        unsigned long size = section_map_size();
        struct page *map = sparse_buffer_alloc(size);
@@ -648,9 +648,9 @@ void offline_mem_sections(unsigned long start_pfn, unsigned 
long end_pfn)
#ifdef CONFIG_SPARSEMEM_VMEMMAP
  static struct page * __meminit populate_section_memmap(unsigned long pfn,
-               unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
+               unsigned long nr_pages, int nid, struct vmem_context *ctx)
  {
-       return __populate_section_memmap(pfn, nr_pages, nid, altmap);
+       return __populate_section_memmap(pfn, nr_pages, nid, ctx);
  }
static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
@@ -842,7 +842,7 @@ static void section_deactivate(unsigned long pfn, unsigned 
long nr_pages,
  }
static struct page * __meminit section_activate(int nid, unsigned long pfn,
-               unsigned long nr_pages, struct vmem_altmap *altmap)
+               unsigned long nr_pages, struct vmem_context *ctx)
  {
        struct mem_section *ms = __pfn_to_section(pfn);
        struct mem_section_usage *usage = NULL;
@@ -874,9 +874,9 @@ static struct page * __meminit section_activate(int nid, 
unsigned long pfn,
        if (nr_pages < PAGES_PER_SECTION && early_section(ms))
                return pfn_to_page(pfn);
- memmap = populate_section_memmap(pfn, nr_pages, nid, altmap);
+       memmap = populate_section_memmap(pfn, nr_pages, nid, ctx);
        if (!memmap) {
-               section_deactivate(pfn, nr_pages, altmap);
+               section_deactivate(pfn, nr_pages, ctx->altmap);
                return ERR_PTR(-ENOMEM);
        }
@@ -902,7 +902,7 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn,
   * * -ENOMEM  - Out of memory.
   */
  int __meminit sparse_add_section(int nid, unsigned long start_pfn,
-               unsigned long nr_pages, struct vmem_altmap *altmap)
+               unsigned long nr_pages, struct vmem_context *ctx)
  {
        unsigned long section_nr = pfn_to_section_nr(start_pfn);
        struct mem_section *ms;
@@ -913,7 +913,7 @@ int __meminit sparse_add_section(int nid, unsigned long 
start_pfn,
        if (ret < 0)
                return ret;
- memmap = section_activate(nid, start_pfn, nr_pages, altmap);
+       memmap = section_activate(nid, start_pfn, nr_pages, ctx);
        if (IS_ERR(memmap))
                return PTR_ERR(memmap);
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