When "crashkernel=X,high" is specified, the specified "crashkernel=Y,low"
memory is not required in the following corner cases:
1. If both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, it means
that the devices can access any memory.
2. If the system memory is small, the crash high memory may be allocated
from the DMA zones. If that happens, there's no need to allocate
another crash low memory because there's already one.
Add condition '(crash_base >= CRASH_ADDR_LOW_MAX)' to determine whether
the 'high' memory is allocated above DMA zones. Note: when both
CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, the entire physical
memory is DMA accessible, CRASH_ADDR_LOW_MAX equals 'PHYS_MASK + 1'.
Signed-off-by: Zhen Lei <[email protected]>
---
Documentation/admin-guide/kernel-parameters.txt | 5 +++--
arch/arm64/mm/init.c | 3 ++-
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f6ff55840751a78..1b543c3109f4851 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -823,7 +823,7 @@
low memory is needed to make sure DMA buffers for 32-bit
devices won't run out. Kernel would try to allocate
at least 256M below 4G automatically.
- This one let user to specify own low range under 4G
+ This one lets the user specify own low range under 4G
for second kernel instead.
0: to disable low allocation.
It will be ignored when crashkernel=X,high is not used
@@ -832,7 +832,8 @@
[KNL, ARM64] range in low memory.
This one lets the user specify a low range in the
DMA zone for the crash dump kernel.
- It will be ignored when crashkernel=X,high is not used.
+ It will be ignored when crashkernel=X,high is not used
+ or memory reserved is located in the DMA zones.
cryptomgr.notests
[KNL] Disable crypto self-tests
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 18ba66c90991ea0..ac510fb6a2c0189 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -170,7 +170,8 @@ static void __init reserve_crashkernel(void)
return;
}
- if (crash_low_size && reserve_crashkernel_low(crash_low_size)) {
+ if ((crash_base >= CRASH_ADDR_LOW_MAX) &&
+ crash_low_size && reserve_crashkernel_low(crash_low_size)) {
memblock_phys_free(crash_base, crash_size);
return;
}
--
2.25.1
On 2022/5/11 17:06, Baoquan He wrote:
> On 05/11/22 at 11:20am, Zhen Lei wrote:
>> When "crashkernel=X,high" is specified, the specified "crashkernel=Y,low"
>> memory is not required in the following corner cases:
>> 1. If both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, it means
>> that the devices can access any memory.
>> 2. If the system memory is small, the crash high memory may be allocated
>> from the DMA zones. If that happens, there's no need to allocate
>> another crash low memory because there's already one.
>>
>> Add condition '(crash_base >= CRASH_ADDR_LOW_MAX)' to determine whether
>> the 'high' memory is allocated above DMA zones. Note: when both
>> CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, the entire physical
>> memory is DMA accessible, CRASH_ADDR_LOW_MAX equals 'PHYS_MASK + 1'.
>>
>> Signed-off-by: Zhen Lei <[email protected]>
>> ---
>> Documentation/admin-guide/kernel-parameters.txt | 5 +++--
>> arch/arm64/mm/init.c | 3 ++-
>> 2 files changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index f6ff55840751a78..1b543c3109f4851 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -823,7 +823,7 @@
>> low memory is needed to make sure DMA buffers for 32-bit
>> devices won't run out. Kernel would try to allocate
>> at least 256M below 4G automatically.
>> - This one let user to specify own low range under 4G
>> + This one lets the user specify own low range under 4G
> ~ This one let users specify own low range ...
>
> Other than this nitpick, LGTM
This is Catalin's response a few days ago:
Slightly more correct is "This one lets the user specify..."
I didn't googled "This one lets", but I googled "It lets". I think he wrote it right.
Both "the user" and "users" seem to be right.
>
> Acked-by: Baoquan He <[email protected]>
>
>> for second kernel instead.
>> 0: to disable low allocation.
>> It will be ignored when crashkernel=X,high is not used
>> @@ -832,7 +832,8 @@
>> [KNL, ARM64] range in low memory.
>> This one lets the user specify a low range in the
>> DMA zone for the crash dump kernel.
>> - It will be ignored when crashkernel=X,high is not used.
>> + It will be ignored when crashkernel=X,high is not used
>> + or memory reserved is located in the DMA zones.
>>
>> cryptomgr.notests
>> [KNL] Disable crypto self-tests
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index 18ba66c90991ea0..ac510fb6a2c0189 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -170,7 +170,8 @@ static void __init reserve_crashkernel(void)
>> return;
>> }
>>
>> - if (crash_low_size && reserve_crashkernel_low(crash_low_size)) {
>> + if ((crash_base >= CRASH_ADDR_LOW_MAX) &&
>> + crash_low_size && reserve_crashkernel_low(crash_low_size)) {
>> memblock_phys_free(crash_base, crash_size);
>> return;
>> }
>> --
>> 2.25.1
>>
>
> .
>
--
Regards,
Zhen Lei
On 05/11/22 at 05:50pm, Leizhen (ThunderTown) wrote:
>
>
> On 2022/5/11 17:06, Baoquan He wrote:
> > On 05/11/22 at 11:20am, Zhen Lei wrote:
> >> When "crashkernel=X,high" is specified, the specified "crashkernel=Y,low"
> >> memory is not required in the following corner cases:
> >> 1. If both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, it means
> >> that the devices can access any memory.
> >> 2. If the system memory is small, the crash high memory may be allocated
> >> from the DMA zones. If that happens, there's no need to allocate
> >> another crash low memory because there's already one.
> >>
> >> Add condition '(crash_base >= CRASH_ADDR_LOW_MAX)' to determine whether
> >> the 'high' memory is allocated above DMA zones. Note: when both
> >> CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, the entire physical
> >> memory is DMA accessible, CRASH_ADDR_LOW_MAX equals 'PHYS_MASK + 1'.
> >>
> >> Signed-off-by: Zhen Lei <[email protected]>
> >> ---
> >> Documentation/admin-guide/kernel-parameters.txt | 5 +++--
> >> arch/arm64/mm/init.c | 3 ++-
> >> 2 files changed, 5 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> >> index f6ff55840751a78..1b543c3109f4851 100644
> >> --- a/Documentation/admin-guide/kernel-parameters.txt
> >> +++ b/Documentation/admin-guide/kernel-parameters.txt
> >> @@ -823,7 +823,7 @@
> >> low memory is needed to make sure DMA buffers for 32-bit
> >> devices won't run out. Kernel would try to allocate
> >> at least 256M below 4G automatically.
> >> - This one let user to specify own low range under 4G
> >> + This one lets the user specify own low range under 4G
> > ~ This one let users specify own low range ...
> >
> > Other than this nitpick, LGTM
>
> This is Catalin's response a few days ago:
> Slightly more correct is "This one lets the user specify..."
>
> I didn't googled "This one lets", but I googled "It lets". I think he wrote it right.
>
> Both "the user" and "users" seem to be right.
Yeah, I forgot the 'this one lets' part, and I am fine too with the 'the
use'if it's right. So please ignore the comment.
>
>
> >
> > Acked-by: Baoquan He <[email protected]>
> >
> >> for second kernel instead.
> >> 0: to disable low allocation.
> >> It will be ignored when crashkernel=X,high is not used
> >> @@ -832,7 +832,8 @@
> >> [KNL, ARM64] range in low memory.
> >> This one lets the user specify a low range in the
> >> DMA zone for the crash dump kernel.
> >> - It will be ignored when crashkernel=X,high is not used.
> >> + It will be ignored when crashkernel=X,high is not used
> >> + or memory reserved is located in the DMA zones.
> >>
> >> cryptomgr.notests
> >> [KNL] Disable crypto self-tests
> >> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> >> index 18ba66c90991ea0..ac510fb6a2c0189 100644
> >> --- a/arch/arm64/mm/init.c
> >> +++ b/arch/arm64/mm/init.c
> >> @@ -170,7 +170,8 @@ static void __init reserve_crashkernel(void)
> >> return;
> >> }
> >>
> >> - if (crash_low_size && reserve_crashkernel_low(crash_low_size)) {
> >> + if ((crash_base >= CRASH_ADDR_LOW_MAX) &&
> >> + crash_low_size && reserve_crashkernel_low(crash_low_size)) {
> >> memblock_phys_free(crash_base, crash_size);
> >> return;
> >> }
> >> --
> >> 2.25.1
> >>
> >
> > .
> >
>
> --
> Regards,
> Zhen Lei
>
On 05/11/22 at 11:20am, Zhen Lei wrote:
> When "crashkernel=X,high" is specified, the specified "crashkernel=Y,low"
> memory is not required in the following corner cases:
> 1. If both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, it means
> that the devices can access any memory.
> 2. If the system memory is small, the crash high memory may be allocated
> from the DMA zones. If that happens, there's no need to allocate
> another crash low memory because there's already one.
>
> Add condition '(crash_base >= CRASH_ADDR_LOW_MAX)' to determine whether
> the 'high' memory is allocated above DMA zones. Note: when both
> CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, the entire physical
> memory is DMA accessible, CRASH_ADDR_LOW_MAX equals 'PHYS_MASK + 1'.
>
> Signed-off-by: Zhen Lei <[email protected]>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 5 +++--
> arch/arm64/mm/init.c | 3 ++-
> 2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index f6ff55840751a78..1b543c3109f4851 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -823,7 +823,7 @@
> low memory is needed to make sure DMA buffers for 32-bit
> devices won't run out. Kernel would try to allocate
> at least 256M below 4G automatically.
> - This one let user to specify own low range under 4G
> + This one lets the user specify own low range under 4G
~ This one let users specify own low range ...
Other than this nitpick, LGTM
Acked-by: Baoquan He <[email protected]>
> for second kernel instead.
> 0: to disable low allocation.
> It will be ignored when crashkernel=X,high is not used
> @@ -832,7 +832,8 @@
> [KNL, ARM64] range in low memory.
> This one lets the user specify a low range in the
> DMA zone for the crash dump kernel.
> - It will be ignored when crashkernel=X,high is not used.
> + It will be ignored when crashkernel=X,high is not used
> + or memory reserved is located in the DMA zones.
>
> cryptomgr.notests
> [KNL] Disable crypto self-tests
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 18ba66c90991ea0..ac510fb6a2c0189 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -170,7 +170,8 @@ static void __init reserve_crashkernel(void)
> return;
> }
>
> - if (crash_low_size && reserve_crashkernel_low(crash_low_size)) {
> + if ((crash_base >= CRASH_ADDR_LOW_MAX) &&
> + crash_low_size && reserve_crashkernel_low(crash_low_size)) {
> memblock_phys_free(crash_base, crash_size);
> return;
> }
> --
> 2.25.1
>
On Wed, 11 May 2022 11:20:32 +0800, Zhen Lei wrote:
> When "crashkernel=X,high" is specified, the specified "crashkernel=Y,low"
> memory is not required in the following corner cases:
> 1. If both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, it means
> that the devices can access any memory.
> 2. If the system memory is small, the crash high memory may be allocated
> from the DMA zones. If that happens, there's no need to allocate
> another crash low memory because there's already one.
>
> [...]
Applied to arm64 (for-next/crashkernel), thanks!
[1/1] arm64: kdump: Do not allocate crash low memory if not needed
https://git.kernel.org/arm64/c/8f0f104e2ab6
--
Catalin