[PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

Subsystems: arm64 port (aarch64 architecture), the rest

STALE2284d REVIEWED: 1 (0M)

1 review trailer.

10 messages, 5 authors, 2020-06-18 · open the first message on its own page

[PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

From: Barry Song <hidden>
Date: 2020-06-16 22:21:11 

hugetlb_cma_reserve() is called at the wrong place. numa_init has not been
done yet. so all reserved memory will be located at node0.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Roman Gushchin <redacted>
Signed-off-by: Barry Song <redacted>
---
 -v2: add Fixes tag according to Matthias Brugger's comment

 arch/arm64/mm/init.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 
 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
-
 }
 
 void __init bootmem_init(void)
@@ -424,6 +419,11 @@ void __init bootmem_init(void)
 	min_low_pfn = min;
 
 	arm64_numa_init();
+
+#ifdef CONFIG_ARM64_4K_PAGES
+	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
+#endif
+
 	/*
 	 * Sparsemem tries to allocate bootmem in memory_present(), so must be
 	 * done after the fixed reservations.
-- 
2.23.0



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Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

From: Anshuman Khandual <hidden>
Date: 2020-06-17 04:12:34 


On 06/17/2020 03:49 AM, Barry Song wrote:
quoted hunk
hugetlb_cma_reserve() is called at the wrong place. numa_init has not been
done yet. so all reserved memory will be located at node0.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Roman Gushchin <redacted>
Signed-off-by: Barry Song <redacted>
---
 -v2: add Fixes tag according to Matthias Brugger's comment

 arch/arm64/mm/init.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 
 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
-
 }
 
 void __init bootmem_init(void)
@@ -424,6 +419,11 @@ void __init bootmem_init(void)
 	min_low_pfn = min;
 
 	arm64_numa_init();
+
+#ifdef CONFIG_ARM64_4K_PAGES
+	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
+#endif
arm64_numa_init() calls numa_init() which initializes node_online_map
that gets used in hugetlb_cma_reserve() while allocating required CMA
size across online nodes.

Reviewed-by: Anshuman Khandual <redacted>

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Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

From: Matthias Brugger <matthias.bgg@gmail.com>
Date: 2020-06-17 09:38:39 


On 17/06/2020 00:19, Barry Song wrote:
hugetlb_cma_reserve() is called at the wrong place. numa_init has not been
done yet. so all reserved memory will be located at node0.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Roman Gushchin <redacted>
Signed-off-by: Barry Song <redacted>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
quoted hunk
---
 -v2: add Fixes tag according to Matthias Brugger's comment

 arch/arm64/mm/init.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 
 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
-
 }
 
 void __init bootmem_init(void)
@@ -424,6 +419,11 @@ void __init bootmem_init(void)
 	min_low_pfn = min;
 
 	arm64_numa_init();
+
+#ifdef CONFIG_ARM64_4K_PAGES
+	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
+#endif
+
 	/*
 	 * Sparsemem tries to allocate bootmem in memory_present(), so must be
 	 * done after the fixed reservations.
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Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

From: Will Deacon <will@kernel.org>
Date: 2020-06-17 10:18:32 

On Wed, Jun 17, 2020 at 10:19:24AM +1200, Barry Song wrote:
hugetlb_cma_reserve() is called at the wrong place. numa_init has not been
done yet. so all reserved memory will be located at node0.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Damn, wasn't CC'd on that :/
quoted hunk
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Roman Gushchin <redacted>
Signed-off-by: Barry Song <redacted>
---
 -v2: add Fixes tag according to Matthias Brugger's comment

 arch/arm64/mm/init.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 
 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
Why is this dependent on CONFIG_ARM64_4K_PAGES? We unconditionally
select ARCH_HAS_GIGANTIC_PAGE so this seems unnecessary.
quoted hunk
-
 }
 
 void __init bootmem_init(void)
@@ -424,6 +419,11 @@ void __init bootmem_init(void)
 	min_low_pfn = min;
 
 	arm64_numa_init();
+
+#ifdef CONFIG_ARM64_4K_PAGES
+	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
+#endif
A comment here wouldn't hurt, as it does look a lot more natural next
to dma_contiguous_reserve().

Will

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RE: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

From: Song Bao Hua (Barry Song) <hidden>
Date: 2020-06-17 11:38:18 

-----Original Message-----
From: Will Deacon [mailto:will@kernel.org]
Sent: Wednesday, June 17, 2020 10:18 PM
To: Song Bao Hua (Barry Song) <redacted>
Cc: catalin.marinas@arm.com; nsaenzjulienne@suse.de;
steve.capper@arm.com; rppt@linux.ibm.com; akpm@linux-foundation.org;
linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; Linuxarm
[off-list ref]; Matthias Brugger [off-list ref];
Roman Gushchin [off-list ref]
Subject: Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

On Wed, Jun 17, 2020 at 10:19:24AM +1200, Barry Song wrote:
quoted
hugetlb_cma_reserve() is called at the wrong place. numa_init has not been
done yet. so all reserved memory will be located at node0.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages
using cma")

Damn, wasn't CC'd on that :/

quoted
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Roman Gushchin <redacted>
Signed-off-by: Barry Song <redacted>
---
 -v2: add Fixes tag according to Matthias Brugger's comment

 arch/arm64/mm/init.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;

 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
Why is this dependent on CONFIG_ARM64_4K_PAGES? We unconditionally
select ARCH_HAS_GIGANTIC_PAGE so this seems unnecessary.
Roman, would you like to answer this question? Have you found any problem if system
doesn't set 4K_PAGES?

quoted
-
 }

 void __init bootmem_init(void)
@@ -424,6 +419,11 @@ void __init bootmem_init(void)
 	min_low_pfn = min;

 	arm64_numa_init();
+
+#ifdef CONFIG_ARM64_4K_PAGES
+	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
+#endif
A comment here wouldn't hurt, as it does look a lot more natural next
to dma_contiguous_reserve().
Will add some comment here.

Will
barry

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Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

    

      From: Roman Gushchin <hidden>

      Date: 2020-06-17 18:22:18 
    

  

  
On Wed, Jun 17, 2020 at 11:38:03AM +0000, Song Bao Hua (Barry Song) wrote:
quoted
-----Original Message-----
From: Will Deacon [mailto:will@kernel.org]
Sent: Wednesday, June 17, 2020 10:18 PM
To: Song Bao Hua (Barry Song) <redacted>
Cc: catalin.marinas@arm.com; nsaenzjulienne@suse.de;
steve.capper@arm.com; rppt@linux.ibm.com; akpm@linux-foundation.org;
linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; Linuxarm
[off-list ref]; Matthias Brugger [off-list ref];
Roman Gushchin [off-list ref]
Subject: Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

On Wed, Jun 17, 2020 at 10:19:24AM +1200, Barry Song wrote:
quoted
hugetlb_cma_reserve() is called at the wrong place. numa_init has not been
done yet. so all reserved memory will be located at node0.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages
using cma")

Damn, wasn't CC'd on that :/

quoted
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Roman Gushchin <redacted>
Signed-off-by: Barry Song <redacted>
---
 -v2: add Fixes tag according to Matthias Brugger's comment

 arch/arm64/mm/init.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;

 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
Why is this dependent on CONFIG_ARM64_4K_PAGES? We unconditionally
select ARCH_HAS_GIGANTIC_PAGE so this seems unnecessary.
Roman, would you like to answer this question? Have you found any problem if system
doesn't set 4K_PAGES?
No, I was just following the code in arch/arm64/mm/hugetlbpage.c where all
related to PUD-sized pages is guarded by CONFIG_ARM64_4K_PAGES.
Actually I did all my testing on x86-64, I don't even have any arm hardware.

I'm totally fine with removing this #ifdef if it's not needed.

Thanks!

quoted
quoted
-
 }

 void __init bootmem_init(void)
@@ -424,6 +419,11 @@ void __init bootmem_init(void)
 	min_low_pfn = min;

 	arm64_numa_init();
+
+#ifdef CONFIG_ARM64_4K_PAGES
+	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
+#endif
A comment here wouldn't hurt, as it does look a lot more natural next
to dma_contiguous_reserve().
Will add some comment here.

quoted
Will
barry
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RE: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

    

      From: Song Bao Hua (Barry Song) <hidden>

      Date: 2020-06-17 21:44:03 
    

  

  
-----Original Message-----
From: Roman Gushchin [mailto:guro@fb.com]
Sent: Thursday, June 18, 2020 6:20 AM
To: Song Bao Hua (Barry Song) <redacted>
Cc: Will Deacon <will@kernel.org>; catalin.marinas@arm.com;
nsaenzjulienne@suse.de; steve.capper@arm.com; rppt@linux.ibm.com;
akpm@linux-foundation.org; linux-arm-kernel@lists.infradead.org;
linux-kernel@vger.kernel.org; Linuxarm [off-list ref]; Matthias
Brugger [off-list ref]
Subject: Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

On Wed, Jun 17, 2020 at 11:38:03AM +0000, Song Bao Hua (Barry Song)
wrote:
quoted
quoted
-----Original Message-----
From: Will Deacon [mailto:will@kernel.org]
Sent: Wednesday, June 17, 2020 10:18 PM
To: Song Bao Hua (Barry Song) <redacted>
Cc: catalin.marinas@arm.com; nsaenzjulienne@suse.de;
steve.capper@arm.com; rppt@linux.ibm.com;
akpm@linux-foundation.org;
quoted
quoted
linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
Linuxarm
quoted
quoted
[off-list ref]; Matthias Brugger [off-list ref];
Roman Gushchin [off-list ref]
Subject: Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

On Wed, Jun 17, 2020 at 10:19:24AM +1200, Barry Song wrote:
quoted
hugetlb_cma_reserve() is called at the wrong place. numa_init has not
been
quoted
quoted
quoted
done yet. so all reserved memory will be located at node0.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic
hugepages
quoted
quoted
using cma")

Damn, wasn't CC'd on that :/

quoted
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Roman Gushchin <redacted>
Signed-off-by: Barry Song <redacted>
---
 -v2: add Fixes tag according to Matthias Brugger's comment

 arch/arm64/mm/init.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;

 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
Why is this dependent on CONFIG_ARM64_4K_PAGES? We unconditionally
select ARCH_HAS_GIGANTIC_PAGE so this seems unnecessary.
Roman, would you like to answer this question? Have you found any
problem if system
quoted
doesn't set 4K_PAGES?
No, I was just following the code in arch/arm64/mm/hugetlbpage.c where all
related to PUD-sized pages is guarded by CONFIG_ARM64_4K_PAGES.
Actually I did all my testing on x86-64, I don't even have any arm hardware.

I'm totally fine with removing this #ifdef if it's not needed.
At this moment, I would suggest we should keep this "ifdef". Otherwise, hugetlb_cma_reserve() won't be really useful.

For example, while setting PAGE size to 64KB. I got this error in hugetlb_cma_reserve():
hugetlb_cma: cma area should be at least 4194304 MiB
This is absolutely unreasonable.

Supporting hugetlb_cma_reserve() for page sizes other than 4k is a different issue. 
It might be addressed in a separate patch later.

Thanks!

quoted
quoted
quoted
-
 }

 void __init bootmem_init(void)
@@ -424,6 +419,11 @@ void __init bootmem_init(void)
 	min_low_pfn = min;

 	arm64_numa_init();
+
+#ifdef CONFIG_ARM64_4K_PAGES
+	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
+#endif
A comment here wouldn't hurt, as it does look a lot more natural next
to dma_contiguous_reserve().
Will add some comment here.

quoted
Will
barry
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Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

    

      From: Will Deacon <will@kernel.org>

      Date: 2020-06-18 07:19:43 
    

  

  
On Wed, Jun 17, 2020 at 09:43:51PM +0000, Song Bao Hua (Barry Song) wrote:
quoted
From: Roman Gushchin [mailto:guro@fb.com]
On Wed, Jun 17, 2020 at 11:38:03AM +0000, Song Bao Hua (Barry Song)
quoted
quoted
From: Will Deacon [mailto:will@kernel.org]
On Wed, Jun 17, 2020 at 10:19:24AM +1200, Barry Song wrote:
quoted
hugetlb_cma_reserve() is called at the wrong place. numa_init has not
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;

 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
Why is this dependent on CONFIG_ARM64_4K_PAGES? We unconditionally
select ARCH_HAS_GIGANTIC_PAGE so this seems unnecessary.
Roman, would you like to answer this question? Have you found any
problem if system
quoted
doesn't set 4K_PAGES?
No, I was just following the code in arch/arm64/mm/hugetlbpage.c where all
related to PUD-sized pages is guarded by CONFIG_ARM64_4K_PAGES.
Actually I did all my testing on x86-64, I don't even have any arm hardware.

I'm totally fine with removing this #ifdef if it's not needed.
At this moment, I would suggest we should keep this "ifdef". Otherwise, hugetlb_cma_reserve() won't be really useful.

For example, while setting PAGE size to 64KB. I got this error in hugetlb_cma_reserve():
hugetlb_cma: cma area should be at least 4194304 MiB
This is absolutely unreasonable.
Maybe one for RaspberryPi 5, huh? ;)

But ok, I'll take your patch as-is and add a comment about NUMA.

Thanks,

Will

_______________________________________________
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RE: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

    

      From: Song Bao Hua (Barry Song) <hidden>

      Date: 2020-06-18 07:43:56 
    

  

  
-----Original Message-----
From: Will Deacon [mailto:will@kernel.org]
Sent: Thursday, June 18, 2020 7:20 PM
To: Song Bao Hua (Barry Song) <redacted>
Cc: Roman Gushchin <redacted>; catalin.marinas@arm.com;
nsaenzjulienne@suse.de; steve.capper@arm.com; rppt@linux.ibm.com;
akpm@linux-foundation.org; linux-arm-kernel@lists.infradead.org;
linux-kernel@vger.kernel.org; Linuxarm [off-list ref]; Matthias
Brugger [off-list ref]
Subject: Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

On Wed, Jun 17, 2020 at 09:43:51PM +0000, Song Bao Hua (Barry Song)
wrote:
quoted
quoted
From: Roman Gushchin [mailto:guro@fb.com]
On Wed, Jun 17, 2020 at 11:38:03AM +0000, Song Bao Hua (Barry Song)
quoted
quoted
From: Will Deacon [mailto:will@kernel.org]
On Wed, Jun 17, 2020 at 10:19:24AM +1200, Barry Song wrote:
quoted
hugetlb_cma_reserve() is called at the wrong place. numa_init has not
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;

 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
Why is this dependent on CONFIG_ARM64_4K_PAGES? We
unconditionally
quoted
quoted
quoted
quoted
select ARCH_HAS_GIGANTIC_PAGE so this seems unnecessary.
Roman, would you like to answer this question? Have you found any
problem if system
quoted
doesn't set 4K_PAGES?
No, I was just following the code in arch/arm64/mm/hugetlbpage.c where
all
quoted
quoted
related to PUD-sized pages is guarded by CONFIG_ARM64_4K_PAGES.
Actually I did all my testing on x86-64, I don't even have any arm
hardware.
quoted
quoted
I'm totally fine with removing this #ifdef if it's not needed.
At this moment, I would suggest we should keep this "ifdef". Otherwise,
hugetlb_cma_reserve() won't be really useful.
quoted
For example, while setting PAGE size to 64KB. I got this error in
hugetlb_cma_reserve():
quoted
hugetlb_cma: cma area should be at least 4194304 MiB
This is absolutely unreasonable.
Maybe one for RaspberryPi 5, huh? ;)

But ok, I'll take your patch as-is and add a comment about NUMA.
Have you seen the v3 with comment? I've already sent.

Thanks,

Will
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Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

    

      From: Will Deacon <will@kernel.org>

      Date: 2020-06-18 07:44:29 
    

  

  
On Thu, Jun 18, 2020 at 07:43:43AM +0000, Song Bao Hua (Barry Song) wrote:
quoted
-----Original Message-----
From: Will Deacon [mailto:will@kernel.org]
Sent: Thursday, June 18, 2020 7:20 PM
To: Song Bao Hua (Barry Song) <redacted>
Cc: Roman Gushchin <redacted>; catalin.marinas@arm.com;
nsaenzjulienne@suse.de; steve.capper@arm.com; rppt@linux.ibm.com;
akpm@linux-foundation.org; linux-arm-kernel@lists.infradead.org;
linux-kernel@vger.kernel.org; Linuxarm [off-list ref]; Matthias
Brugger [off-list ref]
Subject: Re: [PATCH v2] arm64: mm: reserve hugetlb CMA after numa_init

On Wed, Jun 17, 2020 at 09:43:51PM +0000, Song Bao Hua (Barry Song)
wrote:
quoted
quoted
From: Roman Gushchin [mailto:guro@fb.com]
On Wed, Jun 17, 2020 at 11:38:03AM +0000, Song Bao Hua (Barry Song)
quoted
quoted
From: Will Deacon [mailto:will@kernel.org]
On Wed, Jun 17, 2020 at 10:19:24AM +1200, Barry Song wrote:
quoted
hugetlb_cma_reserve() is called at the wrong place. numa_init has not
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e631e6425165..41914b483d54 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -404,11 +404,6 @@ void __init arm64_memblock_init(void)
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;

 	dma_contiguous_reserve(arm64_dma32_phys_limit);
-
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
Why is this dependent on CONFIG_ARM64_4K_PAGES? We
unconditionally
quoted
quoted
quoted
quoted
select ARCH_HAS_GIGANTIC_PAGE so this seems unnecessary.
Roman, would you like to answer this question? Have you found any
problem if system
quoted
doesn't set 4K_PAGES?
No, I was just following the code in arch/arm64/mm/hugetlbpage.c where
all
quoted
quoted
related to PUD-sized pages is guarded by CONFIG_ARM64_4K_PAGES.
Actually I did all my testing on x86-64, I don't even have any arm
hardware.
quoted
quoted
I'm totally fine with removing this #ifdef if it's not needed.
At this moment, I would suggest we should keep this "ifdef". Otherwise,
hugetlb_cma_reserve() won't be really useful.
quoted
For example, while setting PAGE size to 64KB. I got this error in
hugetlb_cma_reserve():
quoted
hugetlb_cma: cma area should be at least 4194304 MiB
This is absolutely unreasonable.
Maybe one for RaspberryPi 5, huh? ;)

But ok, I'll take your patch as-is and add a comment about NUMA.
Have you seen the v3 with comment? I've already sent.
Thanks, just saw that (I'm going through morning email atm :)

Will

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