diff mbox series

[V3,(RESEND),2/3] mm/sparsemem: Enable vmem_altmap support in vmemmap_alloc_block_buf()

Message ID 1592442930-9380-3-git-send-email-anshuman.khandual@arm.com (mailing list archive)
State New, archived
Headers show
Series arm64: Enable vmemmap mapping from device memory | expand

Commit Message

Anshuman Khandual June 18, 2020, 1:15 a.m. UTC 
There are many instances where vmemap allocation is often switched between
regular memory and device memory just based on whether altmap is available
or not. vmemmap_alloc_block_buf() is used in various platforms to allocate
vmemmap mappings. Lets also enable it to handle altmap based device memory
allocation along with existing regular memory allocations. This will help
in avoiding the altmap based allocation switch in many places.

While here also implement a regular memory allocation fallback mechanism
when the first preferred device memory allocation fails. This will ensure
preserving the existing semantics on powerpc platform. To summarize there
are three different methods to call vmemmap_alloc_block_buf().

(., NULL,   false) /* Allocate from system RAM */
(., altmap, false) /* Allocate from altmap without any fallback */
(., altmap, true)  /* Allocate from altmap with fallback (system RAM) */

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Tested-by: Jia He <justin.he@arm.com>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 arch/arm64/mm/mmu.c       |  3 ++-
 arch/powerpc/mm/init_64.c | 10 +++++-----
 arch/x86/mm/init_64.c     |  6 ++----
 include/linux/mm.h        |  3 ++-
 mm/sparse-vmemmap.c       | 30 ++++++++++++++++++++++++------
 5 files changed, 35 insertions(+), 17 deletions(-)

Comments

Catalin Marinas July 2, 2020, 2:07 p.m. UTC | #1 
On Thu, Jun 18, 2020 at 06:45:29AM +0530, Anshuman Khandual wrote:
> There are many instances where vmemap allocation is often switched between
> regular memory and device memory just based on whether altmap is available
> or not. vmemmap_alloc_block_buf() is used in various platforms to allocate
> vmemmap mappings. Lets also enable it to handle altmap based device memory
> allocation along with existing regular memory allocations. This will help
> in avoiding the altmap based allocation switch in many places.
> 
> While here also implement a regular memory allocation fallback mechanism
> when the first preferred device memory allocation fails. This will ensure
> preserving the existing semantics on powerpc platform. To summarize there
> are three different methods to call vmemmap_alloc_block_buf().
> 
> (., NULL,   false) /* Allocate from system RAM */
> (., altmap, false) /* Allocate from altmap without any fallback */
> (., altmap, true)  /* Allocate from altmap with fallback (system RAM) */
[...]
> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
> index bc73abf0bc25..01e25b56eccb 100644
> --- a/arch/powerpc/mm/init_64.c
> +++ b/arch/powerpc/mm/init_64.c
> @@ -225,12 +225,12 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>  		 * fall back to system memory if the altmap allocation fail.
>  		 */
>  		if (altmap && !altmap_cross_boundary(altmap, start, page_size)) {
> -			p = altmap_alloc_block_buf(page_size, altmap);
> -			if (!p)
> -				pr_debug("altmap block allocation failed, falling back to system memory");
> +			p = vmemmap_alloc_block_buf(page_size, node,
> +						    altmap, true);
> +		} else {
> +			p = vmemmap_alloc_block_buf(page_size, node,
> +						    NULL, false);
>  		}
> -		if (!p)
> -			p = vmemmap_alloc_block_buf(page_size, node);
>  		if (!p)
>  			return -ENOMEM;

Is the fallback argument actually necessary. It may be cleaner to just
leave the code as is with the choice between altmap and NULL. If an arch
needs a fallback (only powerpc), they have the fallback in place
already. I don't see the powerpc code any better after this change.

I'm fine with the altmap argument though.
Anshuman Khandual July 3, 2020, 6:32 a.m. UTC | #2 
On 07/02/2020 07:37 PM, Catalin Marinas wrote:
> On Thu, Jun 18, 2020 at 06:45:29AM +0530, Anshuman Khandual wrote:
>> There are many instances where vmemap allocation is often switched between
>> regular memory and device memory just based on whether altmap is available
>> or not. vmemmap_alloc_block_buf() is used in various platforms to allocate
>> vmemmap mappings. Lets also enable it to handle altmap based device memory
>> allocation along with existing regular memory allocations. This will help
>> in avoiding the altmap based allocation switch in many places.
>>
>> While here also implement a regular memory allocation fallback mechanism
>> when the first preferred device memory allocation fails. This will ensure
>> preserving the existing semantics on powerpc platform. To summarize there
>> are three different methods to call vmemmap_alloc_block_buf().
>>
>> (., NULL,   false) /* Allocate from system RAM */
>> (., altmap, false) /* Allocate from altmap without any fallback */
>> (., altmap, true)  /* Allocate from altmap with fallback (system RAM) */
> [...]
>> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
>> index bc73abf0bc25..01e25b56eccb 100644
>> --- a/arch/powerpc/mm/init_64.c
>> +++ b/arch/powerpc/mm/init_64.c
>> @@ -225,12 +225,12 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>>  		 * fall back to system memory if the altmap allocation fail.
>>  		 */
>>  		if (altmap && !altmap_cross_boundary(altmap, start, page_size)) {
>> -			p = altmap_alloc_block_buf(page_size, altmap);
>> -			if (!p)
>> -				pr_debug("altmap block allocation failed, falling back to system memory");
>> +			p = vmemmap_alloc_block_buf(page_size, node,
>> +						    altmap, true);
>> +		} else {
>> +			p = vmemmap_alloc_block_buf(page_size, node,
>> +						    NULL, false);
>>  		}
>> -		if (!p)
>> -			p = vmemmap_alloc_block_buf(page_size, node);
>>  		if (!p)
>>  			return -ENOMEM;
> 
> Is the fallback argument actually necessary. It may be cleaner to just
> leave the code as is with the choice between altmap and NULL. If an arch
> needs a fallback (only powerpc), they have the fallback in place
> already. I don't see the powerpc code any better after this change.
> 
> I'm fine with the altmap argument though.

Okay. Will drop 'fallback' from vmemmap_alloc_block_buf() and update the
callers. There will also be a single change in the subsequent patch i.e
vmemmap_alloc_block_buf(PMD_SIZE, node, altmap).
Michael Ellerman July 3, 2020, 10:43 a.m. UTC | #3 
Catalin Marinas <catalin.marinas@arm.com> writes:
> On Thu, Jun 18, 2020 at 06:45:29AM +0530, Anshuman Khandual wrote:
>> There are many instances where vmemap allocation is often switched between
>> regular memory and device memory just based on whether altmap is available
>> or not. vmemmap_alloc_block_buf() is used in various platforms to allocate
>> vmemmap mappings. Lets also enable it to handle altmap based device memory
>> allocation along with existing regular memory allocations. This will help
>> in avoiding the altmap based allocation switch in many places.
>> 
>> While here also implement a regular memory allocation fallback mechanism
>> when the first preferred device memory allocation fails. This will ensure
>> preserving the existing semantics on powerpc platform. To summarize there
>> are three different methods to call vmemmap_alloc_block_buf().
>> 
>> (., NULL,   false) /* Allocate from system RAM */
>> (., altmap, false) /* Allocate from altmap without any fallback */
>> (., altmap, true)  /* Allocate from altmap with fallback (system RAM) */
> [...]
>> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
>> index bc73abf0bc25..01e25b56eccb 100644
>> --- a/arch/powerpc/mm/init_64.c
>> +++ b/arch/powerpc/mm/init_64.c
>> @@ -225,12 +225,12 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>>  		 * fall back to system memory if the altmap allocation fail.
>>  		 */
>>  		if (altmap && !altmap_cross_boundary(altmap, start, page_size)) {
>> -			p = altmap_alloc_block_buf(page_size, altmap);
>> -			if (!p)
>> -				pr_debug("altmap block allocation failed, falling back to system memory");
>> +			p = vmemmap_alloc_block_buf(page_size, node,
>> +						    altmap, true);
>> +		} else {
>> +			p = vmemmap_alloc_block_buf(page_size, node,
>> +						    NULL, false);
>>  		}
>> -		if (!p)
>> -			p = vmemmap_alloc_block_buf(page_size, node);
>>  		if (!p)
>>  			return -ENOMEM;
>
> Is the fallback argument actually necessary. It may be cleaner to just
> leave the code as is with the choice between altmap and NULL. If an arch
> needs a fallback (only powerpc), they have the fallback in place
> already. I don't see the powerpc code any better after this change.

Yeah I agree.

cheers
diff mbox series

Patch

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 0adad8859393..7ca21adb4412 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1100,7 +1100,8 @@  int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 		if (pmd_none(READ_ONCE(*pmdp))) {
 			void *p = NULL;
 
-			p = vmemmap_alloc_block_buf(PMD_SIZE, node);
+			p = vmemmap_alloc_block_buf(PMD_SIZE, node,
+						    NULL, false);
 			if (!p)
 				return -ENOMEM;
 
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index bc73abf0bc25..01e25b56eccb 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -225,12 +225,12 @@  int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 		 * fall back to system memory if the altmap allocation fail.
 		 */
 		if (altmap && !altmap_cross_boundary(altmap, start, page_size)) {
-			p = altmap_alloc_block_buf(page_size, altmap);
-			if (!p)
-				pr_debug("altmap block allocation failed, falling back to system memory");
+			p = vmemmap_alloc_block_buf(page_size, node,
+						    altmap, true);
+		} else {
+			p = vmemmap_alloc_block_buf(page_size, node,
+						    NULL, false);
 		}
-		if (!p)
-			p = vmemmap_alloc_block_buf(page_size, node);
 		if (!p)
 			return -ENOMEM;
 
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 19c0ed3271a3..4ae4f767c004 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1463,10 +1463,8 @@  static int __meminit vmemmap_populate_hugepages(unsigned long start,
 		if (pmd_none(*pmd)) {
 			void *p;
 
-			if (altmap)
-				p = altmap_alloc_block_buf(PMD_SIZE, altmap);
-			else
-				p = vmemmap_alloc_block_buf(PMD_SIZE, node);
+			p = vmemmap_alloc_block_buf(PMD_SIZE, node,
+						    altmap, false);
 			if (p) {
 				pte_t entry;
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e40ac543d248..dade7c3f634d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3015,7 +3015,8 @@  pte_t *vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
 			    struct vmem_altmap *altmap);
 void *vmemmap_alloc_block(unsigned long size, int node);
 struct vmem_altmap;
-void *vmemmap_alloc_block_buf(unsigned long size, int node);
+void *vmemmap_alloc_block_buf(unsigned long size, int node,
+			      struct vmem_altmap *altmap, bool sysram_fallback);
 void *altmap_alloc_block_buf(unsigned long size, struct vmem_altmap *altmap);
 void vmemmap_verify(pte_t *, int, unsigned long, unsigned long);
 int vmemmap_populate_basepages(unsigned long start, unsigned long end,
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index ceed10dec31e..388121c5bbcb 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -70,10 +70,31 @@  void * __meminit vmemmap_alloc_block(unsigned long size, int node)
 }
 
 /* need to make sure size is all the same during early stage */
-void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
+void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
+					 struct vmem_altmap *altmap,
+					 bool sysram_fallback)
 {
-	void *ptr = sparse_buffer_alloc(size);
+	void *ptr;
 
+	/*
+	 * There is no point in asking for sysram fallback
+	 * without an altmap request to begin with. So just
+	 * warn here to catch potential call sites that may
+	 * be violating this.
+	 */
+	WARN_ON(!altmap && sysram_fallback);
+
+	if (altmap) {
+		ptr = altmap_alloc_block_buf(size, altmap);
+		if (ptr)
+			return ptr;
+		pr_debug("altmap block allocation failed\n");
+		if (!sysram_fallback)
+			return NULL;
+		pr_debug("falling back to system memory\n");
+	}
+
+	ptr = sparse_buffer_alloc(size);
 	if (!ptr)
 		ptr = vmemmap_alloc_block(size, node);
 	return ptr;
@@ -147,10 +168,7 @@  pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
 		pte_t entry;
 		void *p;
 
-		if (altmap)
-			p = altmap_alloc_block_buf(PAGE_SIZE, altmap);
-		else
-			p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
+		p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap, false);
 		if (!p)
 			return NULL;
 		entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);