[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
allocation failure, unmaps all previously mapped sections using vmemmap_free
and maps the entire request with vmemmap_populate_basepages to allocate 
virtually contiguous memory.
https://lkml.org/lkml/2020/9/10/66

V2: Allocates virtually contiguous memory only for sections that failed
PMD_SIZE allocation, and continous to allocate physically contiguous
memory for other sections.
https://lkml.org/lkml/2020/9/30/1489

V3: Addressed trivial review comments. Pass in altmap to vmemmap_populate_basepages.

Sudarshan Rajagopalan (1):
  arm64/mm: add fallback option to allocate virtually contiguous memory

 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

-- 
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[PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
allocation failure, unmaps all previously mapped sections using vmemmap_free
and maps the entire request with vmemmap_populate_basepages to allocate 
virtually contiguous memory.
https://lkml.org/lkml/2020/9/10/66

V2: Allocates virtually contiguous memory only for sections that failed
PMD_SIZE allocation, and continous to allocate physically contiguous
memory for other sections.
https://lkml.org/lkml/2020/9/30/1489

V3: Addressed trivial review comments. Pass in altmap to vmemmap_populate_basepages.
https://lkml.org/lkml/2020/10/12/1681

V4: Fixes checkpatch warning.

Sudarshan Rajagopalan (1):
  arm64/mm: add fallback option to allocate virtually contiguous memory

 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
allocation failure, unmaps all previously mapped sections using vmemmap_free
and maps the entire request with vmemmap_populate_basepages to allocate 
virtually contiguous memory.
https://lkml.org/lkml/2020/9/10/66

V2: Allocates virtually contiguous memory only for sections that failed
PMD_SIZE allocation, and continous to allocate physically contiguous
memory for other sections.
https://lkml.org/lkml/2020/9/30/1489

V3: Addressed trivial review comments. Pass in altmap to vmemmap_populate_basepages.
https://lkml.org/lkml/2020/10/12/1681

V4: Fixes checkpatch warning.

Sudarshan Rajagopalan (1):
  arm64/mm: add fallback option to allocate virtually contiguous memory

 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project


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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
allocation failure, unmaps all previously mapped sections using vmemmap_free
and maps the entire request with vmemmap_populate_basepages to allocate 
virtually contiguous memory.
https://lkml.org/lkml/2020/9/10/66

V2: Allocates virtually contiguous memory only for sections that failed
PMD_SIZE allocation, and continous to allocate physically contiguous
memory for other sections.
https://lkml.org/lkml/2020/9/30/1489

V3: Addressed trivial review comments. Pass in altmap to vmemmap_populate_basepages.

Sudarshan Rajagopalan (1):
  arm64/mm: add fallback option to allocate virtually contiguous memory

 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

When section mappings are enabled, we allocate vmemmap pages from
physically continuous memory of size PMD_SIZE using
vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
pressure. But when system is highly fragmented and memory blocks are
being hot-added at runtime, its possible that such physically continuous
memory allocations can fail. Rather than failing the memory hot-add
procedure, add a fallback option to allocate vmemmap pages from
discontinuous pages using vmemmap_populate_basepages().

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62fea1b6..44486fd0e883 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			void *p = NULL;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
-			if (!p)
-				return -ENOMEM;
+			if (!p) {
+				if (vmemmap_populate_basepages(addr, next, node, altmap))
+					return -ENOMEM;
+				continue;
+			}
 
 			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
 		} else
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

When section mappings are enabled, we allocate vmemmap pages from
physically continuous memory of size PMD_SIZE using
vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
pressure. But when system is highly fragmented and memory blocks are
being hot-added at runtime, its possible that such physically continuous
memory allocations can fail. Rather than failing the memory hot-add
procedure, add a fallback option to allocate vmemmap pages from
discontinuous pages using vmemmap_populate_basepages().

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62fea1b6..44486fd0e883 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			void *p = NULL;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
-			if (!p)
-				return -ENOMEM;
+			if (!p) {
+				if (vmemmap_populate_basepages(addr, next, node, altmap))
+					return -ENOMEM;
+				continue;
+			}
 
 			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
 		} else
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

When section mappings are enabled, we allocate vmemmap pages from
physically continuous memory of size PMD_SIZE using
vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
pressure. But when system is highly fragmented and memory blocks are
being hot-added at runtime, its possible that such physically continuous
memory allocations can fail. Rather than failing the memory hot-add
procedure, add a fallback option to allocate vmemmap pages from
discontinuous pages using vmemmap_populate_basepages().

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62fea1b6..44486fd0e883 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			void *p = NULL;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
-			if (!p)
-				return -ENOMEM;
+			if (!p) {
+				if (vmemmap_populate_basepages(addr, next, node, altmap))
+					return -ENOMEM;
+				continue;
+			}
 
 			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
 		} else
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project


_______________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

When section mappings are enabled, we allocate vmemmap pages from
physically continuous memory of size PMD_SIZE using
vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
pressure. But when system is highly fragmented and memory blocks are
being hot-added at runtime, its possible that such physically continuous
memory allocations can fail. Rather than failing the memory hot-add
procedure, add a fallback option to allocate vmemmap pages from
discontinuous pages using vmemmap_populate_basepages().

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62fea1b6..44486fd0e883 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			void *p = NULL;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
-			if (!p)
-				return -ENOMEM;
+			if (!p) {
+				if (vmemmap_populate_basepages(addr, next, node, altmap))
+					return -ENOMEM;
+				continue;
+			}
 
 			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
 		} else
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Will Deacon]

On Wed, Oct 14, 2020 at 05:51:23PM -0700, Sudarshan Rajagopalan wrote:
> When section mappings are enabled, we allocate vmemmap pages from
> physically continuous memory of size PMD_SIZE using
> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
> pressure. But when system is highly fragmented and memory blocks are
> being hot-added at runtime, its possible that such physically continuous
> memory allocations can fail. Rather than failing the memory hot-add
> procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().
> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/mm/mmu.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)

Please can you fix the subject? I have three copies of "PATCH v3" from
different days in my inbox. I know it sounds trivial, but getting these
little things right really helps with review, especially when it's sitting
amongst a sea of other patches.

Thanks,

Will

_______________________________________________
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Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Will Deacon]

On Wed, Oct 14, 2020 at 05:51:23PM -0700, Sudarshan Rajagopalan wrote:
> When section mappings are enabled, we allocate vmemmap pages from
> physically continuous memory of size PMD_SIZE using
> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
> pressure. But when system is highly fragmented and memory blocks are
> being hot-added at runtime, its possible that such physically continuous
> memory allocations can fail. Rather than failing the memory hot-add
> procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().
> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/mm/mmu.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)

Please can you fix the subject? I have three copies of "PATCH v3" from
different days in my inbox. I know it sounds trivial, but getting these
little things right really helps with review, especially when it's sitting
amongst a sea of other patches.

Thanks,

Will

Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

On 2020-10-15 01:36, Will Deacon wrote:
> On Wed, Oct 14, 2020 at 05:51:23PM -0700, Sudarshan Rajagopalan wrote:
>> When section mappings are enabled, we allocate vmemmap pages from
>> physically continuous memory of size PMD_SIZE using
>> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
>> pressure. But when system is highly fragmented and memory blocks are
>> being hot-added at runtime, its possible that such physically 
>> continuous
>> memory allocations can fail. Rather than failing the memory hot-add
>> procedure, add a fallback option to allocate vmemmap pages from
>> discontinuous pages using vmemmap_populate_basepages().
>> 
>> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
>> Reviewed-by: Gavin Shan <gshan@redhat.com>
>> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Logan Gunthorpe <logang@deltatee.com>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Steven Price <steven.price@arm.com>
>> ---
>>  arch/arm64/mm/mmu.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> Please can you fix the subject? I have three copies of "PATCH v3" from
> different days in my inbox. I know it sounds trivial, but getting these
> little things right really helps with review, especially when it's 
> sitting
> amongst a sea of other patches.

Yes sure, sorry about that - will change it to "PATCH v4" to make it 
stand out from other patches.

> 
> Thanks,
> 
> Will


Sudarshan

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a 
Linux Foundation Collaborative Project

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Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

On 2020-10-15 01:36, Will Deacon wrote:
> On Wed, Oct 14, 2020 at 05:51:23PM -0700, Sudarshan Rajagopalan wrote:
>> When section mappings are enabled, we allocate vmemmap pages from
>> physically continuous memory of size PMD_SIZE using
>> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
>> pressure. But when system is highly fragmented and memory blocks are
>> being hot-added at runtime, its possible that such physically 
>> continuous
>> memory allocations can fail. Rather than failing the memory hot-add
>> procedure, add a fallback option to allocate vmemmap pages from
>> discontinuous pages using vmemmap_populate_basepages().
>> 
>> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
>> Reviewed-by: Gavin Shan <gshan@redhat.com>
>> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Logan Gunthorpe <logang@deltatee.com>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Steven Price <steven.price@arm.com>
>> ---
>>  arch/arm64/mm/mmu.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> Please can you fix the subject? I have three copies of "PATCH v3" from
> different days in my inbox. I know it sounds trivial, but getting these
> little things right really helps with review, especially when it's 
> sitting
> amongst a sea of other patches.

Yes sure, sorry about that - will change it to "PATCH v4" to make it 
stand out from other patches.

> 
> Thanks,
> 
> Will


Sudarshan

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a 
Linux Foundation Collaborative Project

Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

On 2020-10-16 11:56, Sudarshan Rajagopalan wrote:

Hello Will, Catalin,

Did you have a chance to review this patch? It is reviewed by others and 
haven't seen any Nacks. This patch will be useful to have so that memory 
hotremove doesn't fail when such PMD_SIZE pages aren't available.. which 
is usually the case in low RAM devices.

> When section mappings are enabled, we allocate vmemmap pages from
> physically continuous memory of size PMD_SIZE using
> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
> pressure. But when system is highly fragmented and memory blocks are
> being hot-added at runtime, its possible that such physically 
> continuous
> memory allocations can fail. Rather than failing the memory hot-add
> procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().
> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/mm/mmu.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 75df62fea1b6..44486fd0e883 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long
> start, unsigned long end, int node,
>  			void *p = NULL;
> 
>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> -			if (!p)
> -				return -ENOMEM;
> +			if (!p) {
> +				if (vmemmap_populate_basepages(addr, next, node, altmap))
> +					return -ENOMEM;
> +				continue;
> +			}
> 
>  			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
>  		} else

-- 
Sudarshan

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a 
Linux Foundation Collaborative Project

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Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

On 2020-10-16 11:56, Sudarshan Rajagopalan wrote:

Hello Will, Catalin,

Did you have a chance to review this patch? It is reviewed by others and 
haven't seen any Nacks. This patch will be useful to have so that memory 
hotremove doesn't fail when such PMD_SIZE pages aren't available.. which 
is usually the case in low RAM devices.

> When section mappings are enabled, we allocate vmemmap pages from
> physically continuous memory of size PMD_SIZE using
> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
> pressure. But when system is highly fragmented and memory blocks are
> being hot-added at runtime, its possible that such physically 
> continuous
> memory allocations can fail. Rather than failing the memory hot-add
> procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().
> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/mm/mmu.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 75df62fea1b6..44486fd0e883 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long
> start, unsigned long end, int node,
>  			void *p = NULL;
> 
>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> -			if (!p)
> -				return -ENOMEM;
> +			if (!p) {
> +				if (vmemmap_populate_basepages(addr, next, node, altmap))
> +					return -ENOMEM;
> +				continue;
> +			}
> 
>  			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
>  		} else

-- 
Sudarshan

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a 
Linux Foundation Collaborative Project

Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Catalin Marinas]

On Wed, Nov 04, 2020 at 04:03:36PM -0800, Sudarshan Rajagopalan wrote:
> Did you have a chance to review this patch? It is reviewed by others and
> haven't seen any Nacks. This patch will be useful to have so that memory
> hotremove doesn't fail when such PMD_SIZE pages aren't available.. which is
> usually the case in low RAM devices.

Can you please post it again please with Will's ack? You posted a v4
which I think had the same message-id as v3. Mutt flagged it as
duplicate and I deleted it. Just to be sure (I'll queue it when we get
to -rc3).

Thanks.

-- 
Catalin

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Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Catalin Marinas]

On Wed, Nov 04, 2020 at 04:03:36PM -0800, Sudarshan Rajagopalan wrote:
> Did you have a chance to review this patch? It is reviewed by others and
> haven't seen any Nacks. This patch will be useful to have so that memory
> hotremove doesn't fail when such PMD_SIZE pages aren't available.. which is
> usually the case in low RAM devices.

Can you please post it again please with Will's ack? You posted a v4
which I think had the same message-id as v3. Mutt flagged it as
duplicate and I deleted it. Just to be sure (I'll queue it when we get
to -rc3).

Thanks.

-- 
Catalin

Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Will Deacon]

On Fri, Oct 16, 2020 at 11:56:56AM -0700, Sudarshan Rajagopalan wrote:
> When section mappings are enabled, we allocate vmemmap pages from
> physically continuous memory of size PMD_SIZE using
> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
> pressure. But when system is highly fragmented and memory blocks are
> being hot-added at runtime, its possible that such physically continuous
> memory allocations can fail. Rather than failing the memory hot-add
> procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().
> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/mm/mmu.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 75df62fea1b6..44486fd0e883 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>  			void *p = NULL;
>  
>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> -			if (!p)
> -				return -ENOMEM;
> +			if (!p) {
> +				if (vmemmap_populate_basepages(addr, next, node, altmap))
> +					return -ENOMEM;
> +				continue;
> +			}

Looks fine to me:

Acked-by: Will Deacon <will@kernel.org>

Will

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Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Will Deacon]

On Fri, Oct 16, 2020 at 11:56:56AM -0700, Sudarshan Rajagopalan wrote:
> When section mappings are enabled, we allocate vmemmap pages from
> physically continuous memory of size PMD_SIZE using
> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
> pressure. But when system is highly fragmented and memory blocks are
> being hot-added at runtime, its possible that such physically continuous
> memory allocations can fail. Rather than failing the memory hot-add
> procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().
> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/mm/mmu.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 75df62fea1b6..44486fd0e883 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>  			void *p = NULL;
>  
>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> -			if (!p)
> -				return -ENOMEM;
> +			if (!p) {
> +				if (vmemmap_populate_basepages(addr, next, node, altmap))
> +					return -ENOMEM;
> +				continue;
> +			}

Looks fine to me:

Acked-by: Will Deacon <will@kernel.org>

Will

Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Catalin Marinas]

On Fri, 16 Oct 2020 11:56:55 -0700, Sudarshan Rajagopalan wrote:
> V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
> allocation failure, unmaps all previously mapped sections using vmemmap_free
> and maps the entire request with vmemmap_populate_basepages to allocate
> virtually contiguous memory.
> https://lkml.org/lkml/2020/9/10/66
> 
> V2: Allocates virtually contiguous memory only for sections that failed
> PMD_SIZE allocation, and continous to allocate physically contiguous
> memory for other sections.
> https://lkml.org/lkml/2020/9/30/1489
> 
> [...]

Applied to arm64 (for-next/misc), thanks!

[1/1] arm64/mm: add fallback option to allocate virtually contiguous memory
      https://git.kernel.org/arm64/c/9f84f39f5515

(figured out which v3 and v4 have the same message-id and presumably the
same patch)

-- 
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Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory

[Catalin Marinas]

On Fri, 16 Oct 2020 11:56:55 -0700, Sudarshan Rajagopalan wrote:
> V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
> allocation failure, unmaps all previously mapped sections using vmemmap_free
> and maps the entire request with vmemmap_populate_basepages to allocate
> virtually contiguous memory.
> https://lkml.org/lkml/2020/9/10/66
> 
> V2: Allocates virtually contiguous memory only for sections that failed
> PMD_SIZE allocation, and continous to allocate physically contiguous
> memory for other sections.
> https://lkml.org/lkml/2020/9/30/1489
> 
> [...]

Applied to arm64 (for-next/misc), thanks!

[1/1] arm64/mm: add fallback option to allocate virtually contiguous memory
      https://git.kernel.org/arm64/c/9f84f39f5515

(figured out which v3 and v4 have the same message-id and presumably the
same patch)

-- 
Catalin

[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
allocation failure, unmaps all previously mapped sections using vmemmap_free
and maps the entire request with vmemmap_populate_basepages to allocate 
virtually contiguous memory.
https://lkml.org/lkml/2020/9/10/66

V2: Allocates virtually contiguous memory only for sections that failed
PMD_SIZE allocation, and continous to allocate physically contiguous
memory for other sections.
https://lkml.org/lkml/2020/9/30/1489

V3: Addressed trivial review comments. Pass in altmap to vmemmap_populate_basepages.

Sudarshan Rajagopalan (1):
  arm64/mm: add fallback option to allocate virtually contiguous memory

 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

-- 
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a Linux Foundation Collaborative Project


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[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
allocation failure, unmaps all previously mapped sections using vmemmap_free
and maps the entire request with vmemmap_populate_basepages to allocate 
virtually contiguous memory.
https://lkml.org/lkml/2020/9/10/66

V2: Allocates virtually contiguous memory only for sections that failed
PMD_SIZE allocation, and continous to allocate physically contiguous
memory for other sections.
https://lkml.org/lkml/2020/9/30/1489

V3: Addressed trivial review comments. Pass in altmap to vmemmap_populate_basepages.

Sudarshan Rajagopalan (1):
  arm64/mm: add fallback option to allocate virtually contiguous memory

 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

When section mappings are enabled, we allocate vmemmap pages from physically
continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
mappings are good to reduce TLB pressure. But when system is highly fragmented
and memory blocks are being hot-added at runtime, its possible that such
physically continuous memory allocations can fail. Rather than failing the
memory hot-add procedure, add a fallback option to allocate vmemmap pages from
discontinuous pages using vmemmap_populate_basepages().

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62fea1b6..44486fd0e883 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			void *p = NULL;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
-			if (!p)
-				return -ENOMEM;
+			if (!p) {
+				if (vmemmap_populate_basepages(addr, next, node, altmap))
+					return -ENOMEM;
+				continue;
+			}
 
 			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
 		} else
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project


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[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

When section mappings are enabled, we allocate vmemmap pages from physically
continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
mappings are good to reduce TLB pressure. But when system is highly fragmented
and memory blocks are being hot-added at runtime, its possible that such
physically continuous memory allocations can fail. Rather than failing the
memory hot-add procedure, add a fallback option to allocate vmemmap pages from
discontinuous pages using vmemmap_populate_basepages().

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/mmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62fea1b6..44486fd0e883 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			void *p = NULL;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
-			if (!p)
-				return -ENOMEM;
+			if (!p) {
+				if (vmemmap_populate_basepages(addr, next, node, altmap))
+					return -ENOMEM;
+				continue;
+			}
 
 			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
 		} else
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Anshuman Khandual]

On 10/13/2020 04:35 AM, Sudarshan Rajagopalan wrote:
> When section mappings are enabled, we allocate vmemmap pages from physically
> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
> mappings are good to reduce TLB pressure. But when system is highly fragmented
> and memory blocks are being hot-added at runtime, its possible that such
> physically continuous memory allocations can fail. Rather than failing the
> memory hot-add procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().

There is a checkpatch warning here, which could be fixed while merging ?

WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#7: 
When section mappings are enabled, we allocate vmemmap pages from physically

total: 0 errors, 1 warnings, 13 lines checked

> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>

Nonetheless, this looks fine. Did not see any particular problem
while creating an experimental vmemmap with interleaving section
and base page mapping.

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

> ---
>  arch/arm64/mm/mmu.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 75df62fea1b6..44486fd0e883 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>  			void *p = NULL;
>  
>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> -			if (!p)
> -				return -ENOMEM;
> +			if (!p) {
> +				if (vmemmap_populate_basepages(addr, next, node, altmap))
> +					return -ENOMEM;
> +				continue;
> +			}
>  
>  			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
>  		} else
>

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Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Anshuman Khandual]

On 10/13/2020 04:35 AM, Sudarshan Rajagopalan wrote:
> When section mappings are enabled, we allocate vmemmap pages from physically
> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
> mappings are good to reduce TLB pressure. But when system is highly fragmented
> and memory blocks are being hot-added at runtime, its possible that such
> physically continuous memory allocations can fail. Rather than failing the
> memory hot-add procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().

There is a checkpatch warning here, which could be fixed while merging ?

WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#7: 
When section mappings are enabled, we allocate vmemmap pages from physically

total: 0 errors, 1 warnings, 13 lines checked

> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>

Nonetheless, this looks fine. Did not see any particular problem
while creating an experimental vmemmap with interleaving section
and base page mapping.

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

> ---
>  arch/arm64/mm/mmu.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 75df62fea1b6..44486fd0e883 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>  			void *p = NULL;
>  
>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> -			if (!p)
> -				return -ENOMEM;
> +			if (!p) {
> +				if (vmemmap_populate_basepages(addr, next, node, altmap))
> +					return -ENOMEM;
> +				continue;
> +			}
>  
>  			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
>  		} else
>

Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

On 2020-10-13 04:38, Anshuman Khandual wrote:
> On 10/13/2020 04:35 AM, Sudarshan Rajagopalan wrote:
>> When section mappings are enabled, we allocate vmemmap pages from 
>> physically
>> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). 
>> Section
>> mappings are good to reduce TLB pressure. But when system is highly 
>> fragmented
>> and memory blocks are being hot-added at runtime, its possible that 
>> such
>> physically continuous memory allocations can fail. Rather than failing 
>> the
>> memory hot-add procedure, add a fallback option to allocate vmemmap 
>> pages from
>> discontinuous pages using vmemmap_populate_basepages().
> 
> There is a checkpatch warning here, which could be fixed while merging 
> ?
> 
> WARNING: Possible unwrapped commit description (prefer a maximum 75
> chars per line)
> #7:
> When section mappings are enabled, we allocate vmemmap pages from 
> physically
> 
> total: 0 errors, 1 warnings, 13 lines checked
> 

Thanks Anshuman for the review. I sent out an updated patch fixing the 
checkpatch warning.

>> 
>> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
>> Reviewed-by: Gavin Shan <gshan@redhat.com>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Logan Gunthorpe <logang@deltatee.com>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Steven Price <steven.price@arm.com>
> 
> Nonetheless, this looks fine. Did not see any particular problem
> while creating an experimental vmemmap with interleaving section
> and base page mapping.
> 
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> 
>> ---
>>  arch/arm64/mm/mmu.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>> 
>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index 75df62fea1b6..44486fd0e883 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long 
>> start, unsigned long end, int node,
>>  			void *p = NULL;
>> 
>>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
>> -			if (!p)
>> -				return -ENOMEM;
>> +			if (!p) {
>> +				if (vmemmap_populate_basepages(addr, next, node, altmap))
>> +					return -ENOMEM;
>> +				continue;
>> +			}
>> 
>>  			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
>>  		} else
>> 


Sudarshan

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Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

On 2020-10-13 04:38, Anshuman Khandual wrote:
> On 10/13/2020 04:35 AM, Sudarshan Rajagopalan wrote:
>> When section mappings are enabled, we allocate vmemmap pages from 
>> physically
>> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). 
>> Section
>> mappings are good to reduce TLB pressure. But when system is highly 
>> fragmented
>> and memory blocks are being hot-added at runtime, its possible that 
>> such
>> physically continuous memory allocations can fail. Rather than failing 
>> the
>> memory hot-add procedure, add a fallback option to allocate vmemmap 
>> pages from
>> discontinuous pages using vmemmap_populate_basepages().
> 
> There is a checkpatch warning here, which could be fixed while merging 
> ?
> 
> WARNING: Possible unwrapped commit description (prefer a maximum 75
> chars per line)
> #7:
> When section mappings are enabled, we allocate vmemmap pages from 
> physically
> 
> total: 0 errors, 1 warnings, 13 lines checked
> 

Thanks Anshuman for the review. I sent out an updated patch fixing the 
checkpatch warning.

>> 
>> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
>> Reviewed-by: Gavin Shan <gshan@redhat.com>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Logan Gunthorpe <logang@deltatee.com>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Steven Price <steven.price@arm.com>
> 
> Nonetheless, this looks fine. Did not see any particular problem
> while creating an experimental vmemmap with interleaving section
> and base page mapping.
> 
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> 
>> ---
>>  arch/arm64/mm/mmu.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>> 
>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index 75df62fea1b6..44486fd0e883 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long 
>> start, unsigned long end, int node,
>>  			void *p = NULL;
>> 
>>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
>> -			if (!p)
>> -				return -ENOMEM;
>> +			if (!p) {
>> +				if (vmemmap_populate_basepages(addr, next, node, altmap))
>> +					return -ENOMEM;
>> +				continue;
>> +			}
>> 
>>  			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
>>  		} else
>> 


Sudarshan

--
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Linux Foundation Collaborative Project

[PATCH v3] arm64/mm: add fallback option to allocate virtually

[Sudarshan Rajagopalan]

V1: The initial patch used the approach to abort at the first instance of PMD_SIZE
allocation failure, unmaps all previously mapped sections using vmemmap_free
and maps the entire request with vmemmap_populate_basepages to allocate
virtually contiguous memory.
https://lkml.org/lkml/2020/9/10/66

V2: Allocates virtually contiguous memory only for sections that failed
PMD_SIZE allocation, and continues to allocate physically contiguous
memory for other sections.
https://lkml.org/lkml/2020/9/30/1489

V3: Addresses Anshuman's comment to allow fallback to altmap base pages
as well if and when required.

Sudarshan Rajagopalan (1):
  arm64/mm: add fallback option to allocate virtually contiguous memory

 arch/arm64/mm/mmu.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

-- 
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a Linux Foundation Collaborative Project


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[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

When section mappings are enabled, we allocate vmemmap pages from physically
continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
mappings are good to reduce TLB pressure. But when system is highly fragmented
and memory blocks are being hot-added at runtime, its possible that such
physically continuous memory allocations can fail. Rather than failing the
memory hot-add procedure, add a fallback option to allocate vmemmap pages from
discontinuous pages using vmemmap_populate_basepages().

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/mmu.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62f..11f8639 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1121,8 +1121,15 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			void *p = NULL;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
-			if (!p)
-				return -ENOMEM;
+			if (!p) {
+				/*
+				 * fallback allocating with virtually
+				 * contiguous memory for this section
+				 */
+				if (vmemmap_populate_basepages(addr, next, node, NULL))
+					return -ENOMEM;
+				continue;
+			}
 
 			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
 		} else
-- 
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a Linux Foundation Collaborative Project


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[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

When section mappings are enabled, we allocate vmemmap pages from physically
continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
mappings are good to reduce TLB pressure. But when system is highly fragmented
and memory blocks are being hot-added at runtime, its possible that such
physically continuous memory allocations can fail. Rather than failing the
memory hot-add procedure, add a fallback option to allocate vmemmap pages from
discontinuous pages using vmemmap_populate_basepages().

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/mmu.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 75df62f..11f8639 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1121,8 +1121,15 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 			void *p = NULL;
 
 			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
-			if (!p)
-				return -ENOMEM;
+			if (!p) {
+				/*
+				 * fallback allocating with virtually
+				 * contiguous memory for this section
+				 */
+				if (vmemmap_populate_basepages(addr, next, node, NULL))
+					return -ENOMEM;
+				continue;
+			}
 
 			pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
 		} else
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Anshuman Khandual]

On 10/02/2020 01:46 AM, Sudarshan Rajagopalan wrote:
> When section mappings are enabled, we allocate vmemmap pages from physically
> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
> mappings are good to reduce TLB pressure. But when system is highly fragmented
> and memory blocks are being hot-added at runtime, its possible that such
> physically continuous memory allocations can fail. Rather than failing the
> memory hot-add procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().
> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/mm/mmu.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 75df62f..11f8639 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1121,8 +1121,15 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>  			void *p = NULL;
>  
>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> -			if (!p)
> -				return -ENOMEM;
> +			if (!p) {
> +				/*
> +				 * fallback allocating with virtually
> +				 * contiguous memory for this section
> +				 */

Mapping is always virtually contiguous with or without huge pages.
Please drop this comment here, as it's obvious.

> +				if (vmemmap_populate_basepages(addr, next, node, NULL))
> +					return -ENOMEM;

Please send in the 'altmap' instead of NULL for allocation from
device memory if and when requested.

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Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Anshuman Khandual]

On 10/02/2020 01:46 AM, Sudarshan Rajagopalan wrote:
> When section mappings are enabled, we allocate vmemmap pages from physically
> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
> mappings are good to reduce TLB pressure. But when system is highly fragmented
> and memory blocks are being hot-added at runtime, its possible that such
> physically continuous memory allocations can fail. Rather than failing the
> memory hot-add procedure, add a fallback option to allocate vmemmap pages from
> discontinuous pages using vmemmap_populate_basepages().
> 
> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/mm/mmu.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 75df62f..11f8639 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1121,8 +1121,15 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>  			void *p = NULL;
>  
>  			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> -			if (!p)
> -				return -ENOMEM;
> +			if (!p) {
> +				/*
> +				 * fallback allocating with virtually
> +				 * contiguous memory for this section
> +				 */

Mapping is always virtually contiguous with or without huge pages.
Please drop this comment here, as it's obvious.

> +				if (vmemmap_populate_basepages(addr, next, node, NULL))
> +					return -ENOMEM;

Please send in the 'altmap' instead of NULL for allocation from
device memory if and when requested.

Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Gavin Shan]

On 10/6/20 2:36 PM, Anshuman Khandual wrote:
> On 10/02/2020 01:46 AM, Sudarshan Rajagopalan wrote:
>> When section mappings are enabled, we allocate vmemmap pages from physically
>> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
>> mappings are good to reduce TLB pressure. But when system is highly fragmented
>> and memory blocks are being hot-added at runtime, its possible that such
>> physically continuous memory allocations can fail. Rather than failing the
>> memory hot-add procedure, add a fallback option to allocate vmemmap pages from
>> discontinuous pages using vmemmap_populate_basepages().
>>
>> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Logan Gunthorpe <logang@deltatee.com>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Steven Price <steven.price@arm.com>
>> ---
>>   arch/arm64/mm/mmu.c | 11 +++++++++--
>>   1 file changed, 9 insertions(+), 2 deletions(-)
>>

It looks good to me with Anshuman's comments fixed:

Reviewed-by: Gavin Shan <gshan@redhat.com>

>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index 75df62f..11f8639 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -1121,8 +1121,15 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>>   			void *p = NULL;
>>   
>>   			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
>> -			if (!p)
>> -				return -ENOMEM;
>> +			if (!p) {
>> +				/*
>> +				 * fallback allocating with virtually
>> +				 * contiguous memory for this section
>> +				 */
> 
> Mapping is always virtually contiguous with or without huge pages.
> Please drop this comment here, as it's obvious.
> 
>> +				if (vmemmap_populate_basepages(addr, next, node, NULL))
>> +					return -ENOMEM;
> 
> Please send in the 'altmap' instead of NULL for allocation from
> device memory if and when requested.
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 


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Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Gavin Shan]

On 10/6/20 2:36 PM, Anshuman Khandual wrote:
> On 10/02/2020 01:46 AM, Sudarshan Rajagopalan wrote:
>> When section mappings are enabled, we allocate vmemmap pages from physically
>> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
>> mappings are good to reduce TLB pressure. But when system is highly fragmented
>> and memory blocks are being hot-added at runtime, its possible that such
>> physically continuous memory allocations can fail. Rather than failing the
>> memory hot-add procedure, add a fallback option to allocate vmemmap pages from
>> discontinuous pages using vmemmap_populate_basepages().
>>
>> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Logan Gunthorpe <logang@deltatee.com>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Steven Price <steven.price@arm.com>
>> ---
>>   arch/arm64/mm/mmu.c | 11 +++++++++--
>>   1 file changed, 9 insertions(+), 2 deletions(-)
>>

It looks good to me with Anshuman's comments fixed:

Reviewed-by: Gavin Shan <gshan@redhat.com>

>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index 75df62f..11f8639 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -1121,8 +1121,15 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>>   			void *p = NULL;
>>   
>>   			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
>> -			if (!p)
>> -				return -ENOMEM;
>> +			if (!p) {
>> +				/*
>> +				 * fallback allocating with virtually
>> +				 * contiguous memory for this section
>> +				 */
> 
> Mapping is always virtually contiguous with or without huge pages.
> Please drop this comment here, as it's obvious.
> 
>> +				if (vmemmap_populate_basepages(addr, next, node, NULL))
>> +					return -ENOMEM;
> 
> Please send in the 'altmap' instead of NULL for allocation from
> device memory if and when requested.
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>