Re: [v2 3/5] mm: add "zero" argument to vmemmap allocators

2017-05-03 Thread Pasha Tatashin 

Hi Dave,

Thank you for the review. I will address your comment and update patchset..

Pasha

On 05/03/2017 10:34 AM, David Miller wrote:

From: Pavel Tatashin 
Date: Fri, 24 Mar 2017 15:19:50 -0400


Allow clients to request non-zeroed memory from vmemmap allocator.
The following two public function have a new boolean argument called zero:

__vmemmap_alloc_block_buf()
vmemmap_alloc_block()

When zero is true, memory that is allocated by memblock allocator is zeroed
(the current behavior), when argument is false, the memory is not zeroed.

This change allows for optimizations where client knows when it is better
to zero memory: may be later when other CPUs are started, or may be client
is going to set every byte in the allocated memory, so no need to zero
memory beforehand.

Signed-off-by: Pavel Tatashin 
Reviewed-by: Shannon Nelson 


I think when you add a new argument that can adjust behavior, you
should add the new argument but retain exactly the current behavior in
the existing calls.

Then later you can piece by piece change behavior, and document properly
in the commit message what is happening and why the transformation is
legal.

Here, you are adding the new boolean to __earlyonly_bootmem_alloc() and
then making sparse_mem_maps_populate_node() pass false, which changes
behavior such that it doesn't get zero'd memory any more.

Please make one change at a time.  Otherwise review and bisection is
going to be difficult.

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Re: [v2 3/5] mm: add "zero" argument to vmemmap allocators

2017-05-03 Thread David Miller 
From: Pavel Tatashin 
Date: Fri, 24 Mar 2017 15:19:50 -0400

> Allow clients to request non-zeroed memory from vmemmap allocator.
> The following two public function have a new boolean argument called zero:
> 
> __vmemmap_alloc_block_buf()
> vmemmap_alloc_block()
> 
> When zero is true, memory that is allocated by memblock allocator is zeroed
> (the current behavior), when argument is false, the memory is not zeroed.
> 
> This change allows for optimizations where client knows when it is better
> to zero memory: may be later when other CPUs are started, or may be client
> is going to set every byte in the allocated memory, so no need to zero
> memory beforehand.
> 
> Signed-off-by: Pavel Tatashin 
> Reviewed-by: Shannon Nelson 

I think when you add a new argument that can adjust behavior, you
should add the new argument but retain exactly the current behavior in
the existing calls.

Then later you can piece by piece change behavior, and document properly
in the commit message what is happening and why the transformation is
legal.

Here, you are adding the new boolean to __earlyonly_bootmem_alloc() and
then making sparse_mem_maps_populate_node() pass false, which changes
behavior such that it doesn't get zero'd memory any more.

Please make one change at a time.  Otherwise review and bisection is
going to be difficult.

[v2 3/5] mm: add "zero" argument to vmemmap allocators

2017-03-24 Thread Pavel Tatashin 
Allow clients to request non-zeroed memory from vmemmap allocator.
The following two public function have a new boolean argument called zero:

__vmemmap_alloc_block_buf()
vmemmap_alloc_block()

When zero is true, memory that is allocated by memblock allocator is zeroed
(the current behavior), when argument is false, the memory is not zeroed.

This change allows for optimizations where client knows when it is better
to zero memory: may be later when other CPUs are started, or may be client
is going to set every byte in the allocated memory, so no need to zero
memory beforehand.

Signed-off-by: Pavel Tatashin 
Reviewed-by: Shannon Nelson 
---
 arch/powerpc/mm/init_64.c |4 +-
 arch/s390/mm/vmem.c   |5 ++-
 arch/sparc/mm/init_64.c   |3 +-
 arch/x86/mm/init_64.c |3 +-
 include/linux/mm.h|6 ++--
 mm/sparse-vmemmap.c   |   48 +---
 6 files changed, 43 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 9be9920..eb4c270 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -133,7 +133,7 @@ static int __meminit vmemmap_populated(unsigned long start, 
int page_size)
 
/* allocate a page when required and hand out chunks */
if (!num_left) {
-   next = vmemmap_alloc_block(PAGE_SIZE, node);
+   next = vmemmap_alloc_block(PAGE_SIZE, node, true);
if (unlikely(!next)) {
WARN_ON(1);
return NULL;
@@ -181,7 +181,7 @@ int __meminit vmemmap_populate(unsigned long start, 
unsigned long end, int node)
if (vmemmap_populated(start, page_size))
continue;
 
-   p = vmemmap_alloc_block(page_size, node);
+   p = vmemmap_alloc_block(page_size, node, true);
if (!p)
return -ENOMEM;
 
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index 60d3899..9c75214 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -251,7 +251,8 @@ int __meminit vmemmap_populate(unsigned long start, 
unsigned long end, int node)
if (MACHINE_HAS_EDAT1) {
void *new_page;
 
-   new_page = vmemmap_alloc_block(PMD_SIZE, node);
+   new_page = vmemmap_alloc_block(PMD_SIZE, node,
+  true);
if (!new_page)
goto out;
pmd_val(*pm_dir) = __pa(new_page) | sgt_prot;
@@ -271,7 +272,7 @@ int __meminit vmemmap_populate(unsigned long start, 
unsigned long end, int node)
if (pte_none(*pt_dir)) {
void *new_page;
 
-   new_page = vmemmap_alloc_block(PAGE_SIZE, node);
+   new_page = vmemmap_alloc_block(PAGE_SIZE, node, true);
if (!new_page)
goto out;
pte_val(*pt_dir) = __pa(new_page) | pgt_prot;
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 01eccab..d91e462 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -2541,7 +2541,8 @@ int __meminit vmemmap_populate(unsigned long vstart, 
unsigned long vend,
pmd = pmd_offset(pud, vstart);
pte = pmd_val(*pmd);
if (!(pte & _PAGE_VALID)) {
-   void *block = vmemmap_alloc_block(PMD_SIZE, node);
+   void *block = vmemmap_alloc_block(PMD_SIZE, node,
+ true);
 
if (!block)
return -ENOMEM;
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 15173d3..46101b6 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1176,7 +1176,8 @@ static int __meminit vmemmap_populate_hugepages(unsigned 
long start,
if (pmd_none(*pmd)) {
void *p;
 
-   p = __vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
+   p = __vmemmap_alloc_block_buf(PMD_SIZE, node, altmap,
+ true);
if (p) {
pte_t entry;
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5f01c88..54df194 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2410,13 +2410,13 @@ void sparse_mem_maps_populate_node(struct page 
**map_map,
 pud_t *vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node);
 pmd_t *vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node);
 pte_t *vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node);
-void *vmemmap_alloc_block(unsigned long size, int node);