[PATCH v12 7/9] kdump: add threshold for the required memory
From: Chen Zhou <hidden>
Date: 2020-09-07 17:21:08
Also in:
kexec, linux-doc, lkml
Subsystem:
kdump, the rest · Maintainers:
Andrew Morton, Baoquan He, Mike Rapoport, Pasha Tatashin, Pratyush Yadav, Linus Torvalds
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 <redacted> --- 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
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