People reported that when allocating crashkernel memory using
",high" and ",low" syntax, there were cases where the reservation
of the "high" portion succeeds, but the reservation of the "low"
portion fails. Then kexec can load kdump kernel successfully, but
the boot of kdump kernel fails as there's no low memory. This is
because allocation of low memory for kdump kernel can fail on large
systems for reasons. E.g it could be manually specified crashkernel
low memory is too large to find in memblock region.
In this patch add return value for reserve_crashkernel_low. Then
try to reserve crashkernel low memory after crashkernel high memory
has been allocated. If crashkernel low memory reservation failed
free crashkernel high memory and return. User can take measures
when they found kdump kernel cann't be loaded successfully.
Signed-off-by: Baoquan He <b...@redhat.com>
---
v1->v2:
Boris commented that error value EINVAL is negative, should
use "return -EINVAL".
v2->v3:
Yinghai pointed out that during memblock_reserve, we could double
the memblock reserve array. New memblock reserve could be overlapped
with range for crashkernel high. So we have to reserve crashkernel
high firstly, then free it if crashkernel low memory allocation
failed.
v3->v4:
Dave suggested using "return -ENOMEM" when low memory reservation
failed and printing failure message anyway.
v4->v5:
Andrew suggested changing the content of failure message and taking
higher severity KERN_ERR.
arch/x86/kernel/setup.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index fdb7f2a..e510e61 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -493,7 +493,7 @@ static void __init
memblock_x86_reserve_range_setup_data(void)
# define CRASH_KERNEL_ADDR_HIGH_MAX MAXMEM
#endif
-static void __init reserve_crashkernel_low(void)
+static int __init reserve_crashkernel_low(void)
{
#ifdef CONFIG_X86_64
const unsigned long long alignment = 16<<20; /* 16M */
@@ -522,17 +522,16 @@ static void __init reserve_crashkernel_low(void)
} else {
/* passed with crashkernel=0,low ? */
if (!low_size)
- return;
+ return 0;
}
low_base = memblock_find_in_range(low_size, (1ULL<<32),
low_size, alignment);
if (!low_base) {
- if (!auto_set)
- pr_info("crashkernel low reservation failed - No
suitable area found.\n");
-
- return;
+ pr_err("Failed to reserve %ldMB of low memory for crashkernel,
please try smaller size.\n",
+ (unsigned long)(low_size >> 20));
+ return -ENOMEM;
}
memblock_reserve(low_base, low_size);
@@ -544,6 +543,7 @@ static void __init reserve_crashkernel_low(void)
crashk_low_res.end = low_base + low_size - 1;
insert_resource(&iomem_resource, &crashk_low_res);
#endif
+ return 0;
}
static void __init reserve_crashkernel(void)
@@ -595,6 +595,11 @@ static void __init reserve_crashkernel(void)
}
memblock_reserve(crash_base, crash_size);
+ if (crash_base >= (1ULL<<32) && reserve_crashkernel_low()) {
+ memblock_free(crash_base, crash_size);
+ return;
+ }
+
printk(KERN_INFO "Reserving %ldMB of memory at %ldMB "
"for crashkernel (System RAM: %ldMB)\n",
(unsigned long)(crash_size >> 20),
@@ -604,9 +609,6 @@ static void __init reserve_crashkernel(void)
crashk_res.start = crash_base;
crashk_res.end = crash_base + crash_size - 1;
insert_resource(&iomem_resource, &crashk_res);
-
- if (crash_base >= (1ULL<<32))
- reserve_crashkernel_low();
}
#else
static void __init reserve_crashkernel(void)
--
2.4.0
--
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