On x86_32 Qemu machine with 1GB memory, the cmdline "crashkernel=512M" will
also cause system stall as below:
ACPI: Reserving FACP table memory at [mem 0x3ffe18b8-0x3ffe192b]
ACPI: Reserving DSDT table memory at [mem 0x3ffe0040-0x3ffe18b7]
ACPI: Reserving FACS table memory at [mem 0x3ffe0000-0x3ffe003f]
ACPI: Reserving APIC table memory at [mem 0x3ffe192c-0x3ffe19bb]
ACPI: Reserving HPET table memory at [mem 0x3ffe19bc-0x3ffe19f3]
ACPI: Reserving WAET table memory at [mem 0x3ffe19f4-0x3ffe1a1b]
143MB HIGHMEM available.
879MB LOWMEM available.
mapped low ram: 0 - 36ffe000
low ram: 0 - 36ffe000
(stall here)
The reason is that the CRASH_ADDR_LOW_MAX is equal to CRASH_ADDR_HIGH_MAX
on x86_32, the first "low" crash kernel memory reservation for 512M fails,
then it go into the "retry" loop and never came out as below (consider
CRASH_ADDR_LOW_MAX = CRASH_ADDR_HIGH_MAX = 512M):
-> reserve_crashkernel_generic() and high is false
-> alloc at [0, 0x20000000] fail
-> alloc at [0x20000000, 0x20000000] fail and repeatedly
(because CRASH_ADDR_LOW_MAX = CRASH_ADDR_HIGH_MAX).
Fix it by skipping meaningless calls of memblock_phys_alloc_range() with
`start = end`
After this patch, the retry dead loop is avoided and print below info:
cannot allocate crashkernel (size:0x20000000)
And apply generic crashkernel reservation to 32bit system will be ready.
Fixes: 9c08a2a139fe ("x86: kdump: use generic interface to simplify crashkernel reservation code")
Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
Tested-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
v3:
- Fix it as Baoquan suggested.
- Update the commit message.
---
kernel/crash_reserve.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c
index c5213f123e19..dacc268429e2 100644
--- a/kernel/crash_reserve.c
+++ b/kernel/crash_reserve.c
@@ -414,7 +414,8 @@ void __init reserve_crashkernel_generic(char *cmdline,
search_end = CRASH_ADDR_HIGH_MAX;
search_base = CRASH_ADDR_LOW_MAX;
crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
- goto retry;
+ if (search_base != search_end)
+ goto retry;
}
/*
--
2.34.1
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