Re: [PATCH v12 7/9] kdump: add threshold for the required memory
On 2020/10/6 1:12, Catalin Marinas wrote: > On Mon, Sep 07, 2020 at 09:47:43PM +0800, Chen Zhou wrote: >> diff --git a/kernel/crash_core.c b/kernel/crash_core.c >> index 3f735cb37ace..d11d597a470d 100644 >> --- a/kernel/crash_core.c >> +++ b/kernel/crash_core.c >> @@ -378,6 +378,15 @@ int __init reserve_crashkernel_low(void) >> } >> >> #if defined(CONFIG_X86) || defined(CONFIG_ARM64) >> + >> +/* >> + * Add a threshold for required memory size of crashkernel. If required >> memory >> + * size is greater than threshold, just go for high allocation directly. The >> + * value of threshold is set as half of the total low memory. >> + */ >> +#define REQUIRED_MEMORY_THRESHOLD (memblock_mem_size(CRASH_ADDR_LOW_MAX >> >> \ >> +PAGE_SHIFT) >> 1) >> + >> #ifdef CONFIG_KEXEC_CORE >> /* >> * reserve_crashkernel() - reserves memory for crash kernel >> @@ -422,7 +431,7 @@ void __init reserve_crashkernel(void) >> * So try low memory first and fall back to high memory >> * unless "crashkernel=size[KMG],high" is specified. >> */ >> -if (!high) >> +if (!high && crash_size <= REQUIRED_MEMORY_THRESHOLD) >> crash_base = memblock_find_in_range(CRASH_ALIGN, >> CRASH_ADDR_LOW_MAX, >> crash_size, CRASH_ALIGN); > Since any change now is affecting the x86 semantics slightly, I'd > suggest you drop this patch. We can add it later if needed, once the > core changes are in. Ok, i will drop this patch in next version. Thanks, Chen Zhou > > Thinking about this, if one requires a crashkernel reservation that > allocates all of the ZONE_DMA, it would probably be noticed and explicit > ,high/,low options can be used. > > Note that we are also trying to make ZONE_DMA full 32-bit on non-RPi4 > hardware. >
Re: [PATCH v12 7/9] kdump: add threshold for the required memory
On Mon, Sep 07, 2020 at 09:47:43PM +0800, Chen Zhou wrote: > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 3f735cb37ace..d11d597a470d 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -378,6 +378,15 @@ int __init reserve_crashkernel_low(void) > } > > #if defined(CONFIG_X86) || defined(CONFIG_ARM64) > + > +/* > + * Add a threshold for required memory size of crashkernel. If required > memory > + * size is greater than threshold, just go for high allocation directly. The > + * value of threshold is set as half of the total low memory. > + */ > +#define REQUIRED_MEMORY_THRESHOLD(memblock_mem_size(CRASH_ADDR_LOW_MAX > >> \ > + PAGE_SHIFT) >> 1) > + > #ifdef CONFIG_KEXEC_CORE > /* > * reserve_crashkernel() - reserves memory for crash kernel > @@ -422,7 +431,7 @@ void __init reserve_crashkernel(void) >* So try low memory first and fall back to high memory >* unless "crashkernel=size[KMG],high" is specified. >*/ > - if (!high) > + if (!high && crash_size <= REQUIRED_MEMORY_THRESHOLD) > crash_base = memblock_find_in_range(CRASH_ALIGN, > CRASH_ADDR_LOW_MAX, > crash_size, CRASH_ALIGN); Since any change now is affecting the x86 semantics slightly, I'd suggest you drop this patch. We can add it later if needed, once the core changes are in. Thinking about this, if one requires a crashkernel reservation that allocates all of the ZONE_DMA, it would probably be noticed and explicit ,high/,low options can be used. Note that we are also trying to make ZONE_DMA full 32-bit on non-RPi4 hardware. -- Catalin
[PATCH v12 7/9] kdump: add threshold for the required memory
For crashkernel=X, if required size X is too large and leads to very little free low memory after low allocation, the system may not work normally. So add a threshold and go for high allocation directly if the required size is too large. The value of threshold is set as the half of the low memory. Signed-off-by: Chen Zhou --- kernel/crash_core.c | 11 ++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 3f735cb37ace..d11d597a470d 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -378,6 +378,15 @@ int __init reserve_crashkernel_low(void) } #if defined(CONFIG_X86) || defined(CONFIG_ARM64) + +/* + * Add a threshold for required memory size of crashkernel. If required memory + * size is greater than threshold, just go for high allocation directly. The + * value of threshold is set as half of the total low memory. + */ +#define REQUIRED_MEMORY_THRESHOLD (memblock_mem_size(CRASH_ADDR_LOW_MAX >> \ + PAGE_SHIFT) >> 1) + #ifdef CONFIG_KEXEC_CORE /* * reserve_crashkernel() - reserves memory for crash kernel @@ -422,7 +431,7 @@ void __init reserve_crashkernel(void) * So try low memory first and fall back to high memory * unless "crashkernel=size[KMG],high" is specified. */ - if (!high) + if (!high && crash_size <= REQUIRED_MEMORY_THRESHOLD) crash_base = memblock_find_in_range(CRASH_ALIGN, CRASH_ADDR_LOW_MAX, crash_size, CRASH_ALIGN); -- 2.20.1
