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
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 <[email protected]>
Reviewed-by: Gavin Shan <[email protected]>
Reviewed-by: Anshuman Khandual <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Logan Gunthorpe <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Steven Price <[email protected]>
---
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
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 <[email protected]>
> Reviewed-by: Gavin Shan <[email protected]>
> Reviewed-by: Anshuman Khandual <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Anshuman Khandual <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Logan Gunthorpe <[email protected]>
> Cc: David Hildenbrand <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Steven Price <[email protected]>
> ---
> 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
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 <[email protected]>
>> Reviewed-by: Gavin Shan <[email protected]>
>> Reviewed-by: Anshuman Khandual <[email protected]>
>> Cc: Catalin Marinas <[email protected]>
>> Cc: Will Deacon <[email protected]>
>> Cc: Anshuman Khandual <[email protected]>
>> Cc: Mark Rutland <[email protected]>
>> Cc: Logan Gunthorpe <[email protected]>
>> Cc: David Hildenbrand <[email protected]>
>> Cc: Andrew Morton <[email protected]>
>> Cc: Steven Price <[email protected]>
>> ---
>> 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
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 <[email protected]>
> Reviewed-by: Gavin Shan <[email protected]>
> Reviewed-by: Anshuman Khandual <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Anshuman Khandual <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Logan Gunthorpe <[email protected]>
> Cc: David Hildenbrand <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Steven Price <[email protected]>
> ---
> 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
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 <[email protected]>
> Reviewed-by: Gavin Shan <[email protected]>
> Reviewed-by: Anshuman Khandual <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Anshuman Khandual <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Logan Gunthorpe <[email protected]>
> Cc: David Hildenbrand <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Steven Price <[email protected]>
> ---
> 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 <[email protected]>
Will
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
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