Hi all,
Ping.
Any other suggestion for this fix?
On 09/24/15 at 11:24am, Baoquan He wrote:
> 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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