Re: [PATCH v7 2/4] arm64: kdump: reserve crashkenel above 4G for crash dump kernel

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. Hi John,

On Sun, Mar 8, 2020 at 12:13 AM John Donnelly
<john.p.donnelly@xxxxxxxxxx> wrote:
>
>
>
> > On Mar 7, 2020, at 5:06 AM, Chen Zhou <chenzhou10@xxxxxxxxxx> wrote:
> >
> >
> >
> > On 2020/3/5 18:13, Prabhakar Kushwaha wrote:
> >> On Mon, Dec 23, 2019 at 8:57 PM Chen Zhou <chenzhou10@xxxxxxxxxx> wrote:
> >>>
> >>> Crashkernel=X tries to reserve memory for the crash dump kernel under
> >>> 4G. If crashkernel=X,low is specified simultaneously, reserve spcified
> >>> size low memory for crash kdump kernel devices firstly and then reserve
> >>> memory above 4G.
> >>>
> >>> Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx>
> >>> ---
> >>> arch/arm64/kernel/setup.c |  8 +++++++-
> >>> arch/arm64/mm/init.c      | 31 +++++++++++++++++++++++++++++--
> >>> 2 files changed, 36 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> >>> index 56f6645..04d1c87 100644
> >>> --- a/arch/arm64/kernel/setup.c
> >>> +++ b/arch/arm64/kernel/setup.c
> >>> @@ -238,7 +238,13 @@ static void __init request_standard_resources(void)
> >>>                    kernel_data.end <= res->end)
> >>>                        request_resource(res, &kernel_data);
> >>> #ifdef CONFIG_KEXEC_CORE
> >>> -               /* Userspace will find "Crash kernel" region in /proc/iomem. */
> >>> +               /*
> >>> +                * Userspace will find "Crash kernel" region in /proc/iomem.
> >>> +                * Note: the low region is renamed as Crash kernel (low).
> >>> +                */
> >>> +               if (crashk_low_res.end && crashk_low_res.start >= res->start &&
> >>> +                               crashk_low_res.end <= res->end)
> >>> +                       request_resource(res, &crashk_low_res);
> >>>                if (crashk_res.end && crashk_res.start >= res->start &&
> >>>                    crashk_res.end <= res->end)
> >>>                        request_resource(res, &crashk_res);
> >>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> >>> index b65dffd..0d7afd5 100644
> >>> --- a/arch/arm64/mm/init.c
> >>> +++ b/arch/arm64/mm/init.c
> >>> @@ -80,6 +80,7 @@ static void __init reserve_crashkernel(void)
> >>> {
> >>>        unsigned long long crash_base, crash_size;
> >>>        int ret;
> >>> +       phys_addr_t crash_max = arm64_dma32_phys_limit;
> >>>
> >>>        ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> >>>                                &crash_size, &crash_base);
> >>> @@ -87,12 +88,38 @@ static void __init reserve_crashkernel(void)
> >>>        if (ret || !crash_size)
> >>>                return;
> >>>
> >>> +       ret = reserve_crashkernel_low();
> >>> +       if (!ret && crashk_low_res.end) {
> >>> +               /*
> >>> +                * If crashkernel=X,low specified, there may be two regions,
> >>> +                * we need to make some changes as follows:
> >>> +                *
> >>> +                * 1. rename the low region as "Crash kernel (low)"
> >>> +                * In order to distinct from the high region and make no effect
> >>> +                * to the use of existing kexec-tools, rename the low region as
> >>> +                * "Crash kernel (low)".
> >>> +                *
> >>> +                * 2. change the upper bound for crash memory
> >>> +                * Set MEMBLOCK_ALLOC_ACCESSIBLE upper bound for crash memory.
> >>> +                *
> >>> +                * 3. mark the low region as "nomap"
> >>> +                * The low region is intended to be used for crash dump kernel
> >>> +                * devices, just mark the low region as "nomap" simply.
> >>> +                */
> >>> +               const char *rename = "Crash kernel (low)";
> >>> +
> >>> +               crashk_low_res.name = rename;
> >>> +               crash_max = MEMBLOCK_ALLOC_ACCESSIBLE;
> >>> +               memblock_mark_nomap(crashk_low_res.start,
> >>> +                                   resource_size(&crashk_low_res));
> >>> +       }
> >>> +
> >>>        crash_size = PAGE_ALIGN(crash_size);
> >>>
> >>>        if (crash_base == 0) {
> >>>                /* Current arm64 boot protocol requires 2MB alignment */
> >>> -               crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit,
> >>> -                               crash_size, SZ_2M);
> >>> +               crash_base = memblock_find_in_range(0, crash_max, crash_size,
> >>> +                               SZ_2M);
> >>>                if (crash_base == 0) {
> >>>                        pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
> >>>                                crash_size);
> >>> --
> >>
> >> I tested this patch series on ARM64-ThunderX2 with no issue with
> >> bootargs crashkenel=X@Y crashkernel=250M,low
> >>
> >> $ dmesg | grep crash
> >> [    0.000000] crashkernel reserved: 0x0000000b81200000 -
> >> 0x0000000c81200000 (4096 MB)
> >> [    0.000000] Kernel command line:
> >> BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
> >> root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro
> >> crashkernel=4G@0xb81200000 crashkernel=250M,low nowatchdog earlycon
> >> [   29.310209]     crashkernel=250M,low
> >>
> >> $  kexec -p -i /boot/vmlinuz-`uname -r`
> >> --initrd=/boot/initrd.img-`uname -r` --reuse-cmdline
> >> $ echo 1 > /proc/sys/kernel/sysrq ; echo c > /proc/sysrq-trigger
> >>
> >> But when i tried with crashkernel=4G crashkernel=250M,low as bootargs.
> >> Kernel is not able to allocate memory.
> >> [    0.000000] cannot allocate crashkernel (size:0x100000000)
> >> [    0.000000] Kernel command line:
> >> BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
> >> root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro crashkernel=4G
> >> crashkernel=250M,low nowatchdog
> >> [   29.332081]     crashkernel=250M,low
> >>
> >> does crashkernel=X@Y mandatory to get allocated beyond 4G?
> >> am I missing something?
> >
>
>    crashkernel=4G
>
>    You need to look at the memory map on node 0  from dmesg     ( or /proc/iomem ) to determine if there is any memory in that range  - 0x100000000 == 1st byte above 4G .
>

i believe i have enough free memory. Please find log below

$ dmesg | grep "node 0"
[    0.000000] Initmem setup node 0 [mem 0x00000000802f0000-0x0000009ffcffffff]
[    0.000000] On node 0 totalpages: 33537296
[   12.335714] pci_bus 0000:00: on NUMA node 0
$

I am passing 4G@0xb81200000 in working scenario, here 0xb81200000 is
well within node 0 range.

Logs of iomem is below:

$ cat /proc/iomem
00000000-00000000 : PCI ECAM
00000000-00000000 : PCI ECAM
00000000-00000000 : PCI Bus 0000:00
  00000000-00000000 : PCI Bus 0000:0f
    00000000-00000000 : PCI Bus 0000:10
      00000000-00000000 : 0000:10:00.0
      00000000-00000000 : 0000:10:00.0
  00000000-00000000 : PCI Bus 0000:01
    00000000-00000000 : 0000:01:00.0
    00000000-00000000 : 0000:01:00.1
  00000000-00000000 : PCI Bus 0000:05
    00000000-00000000 : 0000:05:00.0
    00000000-00000000 : 0000:05:00.1
  00000000-00000000 : PCI Bus 0000:09
    00000000-00000000 : 0000:09:00.0
    00000000-00000000 : 0000:09:00.1
  00000000-00000000 : 0000:00:10.0
    00000000-00000000 : ahci
  00000000-00000000 : 0000:00:10.1
    00000000-00000000 : ahci
00000000-00000000 : PCI Bus 0000:80
  00000000-00000000 : PCI Bus 0000:83
    00000000-00000000 : 0000:83:00.0
    00000000-00000000 : 0000:83:00.0
      00000000-00000000 : nvme
  00000000-00000000 : PCI Bus 0000:89
    00000000-00000000 : 0000:89:00.0
      00000000-00000000 : e1000e
    00000000-00000000 : 0000:89:00.0
    00000000-00000000 : 0000:89:00.0
      00000000-00000000 : e1000e
    00000000-00000000 : 0000:89:00.0
      00000000-00000000 : e1000e
  00000000-00000000 : PCI Bus 0000:8d
    00000000-00000000 : 0000:8d:00.0
    00000000-00000000 : 0000:8d:00.0
      00000000-00000000 : mpt3sas
00000000-00000000 : reserved
00000000-00000000 : System RAM
  00000000-00000000 : Kernel code
  00000000-00000000 : reserved
  00000000-00000000 : Kernel data
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
00000000-00000000 : reserved
00000000-00000000 : System RAM
00000000-00000000 : reserved
00000000-00000000 : System RAM
  00000000-00000000 : reserved
00000000-00000000 : reserved
00000000-00000000 : System RAM
  00000000-00000000 : reserved
00000000-00000000 : reserved
00000000-00000000 : System RAM
  00000000-00000000 : reserved
00000000-00000000 : reserved
00000000-00000000 : System RAM
  00000000-00000000 : reserved
00000000-00000000 : reserved
00000000-00000000 : System RAM
  00000000-00000000 : reserved
00000000-00000000 : CAV901C:00
00000000-00000000 : CAV901D:00
  00000000-00000000 : CAV901C:00
00000000-00000000 : CAV901E:00
  00000000-00000000 : CAV901C:00
00000000-00000000 : CAV901F:00
  00000000-00000000 : CAV901C:00
00000000-00000000 : CAV9006:00
  00000000-00000000 : CAV9006:00
00000000-00000000 : ARMH0011:00
  00000000-00000000 : ARMH0011:00
00000000-00000000 : arm-smmu-v3.0.auto
  00000000-00000000 : arm-smmu-v3.0.auto
00000000-00000000 : arm-smmu-v3.1.auto
  00000000-00000000 : arm-smmu-v3.1.auto
00000000-00000000 : arm-smmu-v3.2.auto
  00000000-00000000 : arm-smmu-v3.2.auto
00000000-00000000 : CAV901C:01
00000000-00000000 : CAV901D:01
  00000000-00000000 : CAV901C:01
00000000-00000000 : CAV901E:01
  00000000-00000000 : CAV901C:01
00000000-00000000 : CAV901F:01
  00000000-00000000 : CAV901C:01
00000000-00000000 : CAV9007:06
  00000000-00000000 : CAV9007:06
00000000-00000000 : arm-smmu-v3.3.auto
  00000000-00000000 : arm-smmu-v3.3.auto
00000000-00000000 : arm-smmu-v3.4.auto
  00000000-00000000 : arm-smmu-v3.4.auto
00000000-00000000 : arm-smmu-v3.5.auto
  00000000-00000000 : arm-smmu-v3.5.auto
00000000-00000000 : System RAM
00000000-00000000 : System RAM
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
00000000-00000000 : System RAM
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
  00000000-00000000 : reserved
00000000-00000000 : PCI Bus 0000:00
  00000000-00000000 : PCI Bus 0000:01
    00000000-00000000 : 0000:01:00.0
    00000000-00000000 : 0000:01:00.1
    00000000-00000000 : 0000:01:00.0
    00000000-00000000 : 0000:01:00.1
    00000000-00000000 : 0000:01:00.0
    00000000-00000000 : 0000:01:00.1
  00000000-00000000 : PCI Bus 0000:05
    00000000-00000000 : 0000:05:00.0
      00000000-00000000 : bnx2x
    00000000-00000000 : 0000:05:00.1
      00000000-00000000 : bnx2x
    00000000-00000000 : 0000:05:00.0
      00000000-00000000 : bnx2x
    00000000-00000000 : 0000:05:00.0
      00000000-00000000 : bnx2x
    00000000-00000000 : 0000:05:00.1
      00000000-00000000 : bnx2x
    00000000-00000000 : 0000:05:00.1
      00000000-00000000 : bnx2x
  00000000-00000000 : PCI Bus 0000:09
    00000000-00000000 : 0000:09:00.0
      00000000-00000000 : i40e
    00000000-00000000 : 0000:09:00.1
      00000000-00000000 : i40e
    00000000-00000000 : 0000:09:00.0
    00000000-00000000 : 0000:09:00.1
    00000000-00000000 : 0000:09:00.0
      00000000-00000000 : i40e
    00000000-00000000 : 0000:09:00.1
      00000000-00000000 : i40e
    00000000-00000000 : 0000:09:00.0
    00000000-00000000 : 0000:09:00.1
  00000000-00000000 : 0000:00:0f.0
    00000000-00000000 : xhci-hcd
  00000000-00000000 : 0000:00:0f.0
  00000000-00000000 : 0000:00:0f.1
    00000000-00000000 : xhci-hcd
  00000000-00000000 : 0000:00:0f.1
  00000000-00000000 : 0000:00:10.0
    00000000-00000000 : ahci
  00000000-00000000 : 0000:00:10.1
    00000000-00000000 : ahci
00000000-00000000 : PCI Bus 0000:80

--pk

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