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 <chenzhou10@xxxxxxxxxx> --- 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
