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

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Hi Chen,

On Sat, Mar 7, 2020 at 4:36 PM 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?
>
> I can't reproduce the problem in my environment, can you test with other size,
> such as "crashkernel=1G crashkernel=250M,low", see if there is the same issue.
>
I tried 1G also. Same error, please find the logs

$ dmesg | grep crash
[    0.000000] cannot allocate crashkernel (size:0x40000000)
[    0.000000] Kernel command line:
BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro nowatchdog earlycon
crashkernel=1G crashkernel=250M,low
[   29.326916]     crashkernel=250M,low


> Besides, crashkernel=X@Y isn't mandatory to get allocated beyond 4G,

this was my understanding also.

> can you show the whole file /proc/iomem.
>

$ 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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