Hi Bhupesh,


On 2020/10/6 1:42, Bhupesh Sharma wrote:

Hi Catalin, Chen,

On Mon, Oct 5, 2020 at 10:39 PM Catalin Marinas [off-list ref] wrote:

quoted

On Sat, Sep 12, 2020 at 06:44:29AM -0500, John Donnelly wrote:

quoted

On 9/7/20 8:47 AM, Chen Zhou wrote:

quoted

Chen Zhou (9):
   x86: kdump: move CRASH_ALIGN to 2M
   x86: kdump: make the lower bound of crash kernel reservation
     consistent
   x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions
     reserve_crashkernel[_low]()
   x86: kdump: move reserve_crashkernel[_low]() into crash_core.c
   arm64: kdump: introduce some macroes for crash kernel reservation
   arm64: kdump: reimplement crashkernel=X
   kdump: add threshold for the required memory
   arm64: kdump: add memory for devices by DT property
     linux,usable-memory-range
   kdump: update Documentation about crashkernel

[...]

quoted

I did a brief unit-test on 5.9-rc4.

Please add:

Tested-by:  John Donnelly <redacted>

Thanks for testing.

quoted

This activity is over a year old. It needs accepted.

It's getting there, hopefully in 5.11. There are some minor tweaks to
address.

I think my earlier email with the test results on this series bounced
off the mailing list server (for some weird reason), but I still see
several issues with this patchset. I will add specific issues in the
review comments for each patch again, but overall, with a crashkernel
size of say 786M, I see the following issue:

# cat /proc/cmdline
BOOT_IMAGE=(hd7,gpt2)/vmlinuz-5.9.0-rc7+ root=<..snip..>
rd.lvm.lv=<..snip..> crashkernel=786M

I see two regions of size 786M and 256M reserved in low and high
regions respectively, So we reserve a total of 1042M of memory, which
is an incorrect behaviour:

# dmesg | grep -i crash
[    0.000000] Reserving 256MB of low memory at 2816MB for crashkernel
(System low RAM: 768MB)
[    0.000000] Reserving 786MB of memory at 654158MB for crashkernel
(System RAM: 130816MB)
[    0.000000] Kernel command line:
BOOT_IMAGE=(hd2,gpt2)/vmlinuz-5.9.0-rc7+
root=/dev/mapper/rhel_ampere--hr330a--03-root ro
rd.lvm.lv=rhel_ampere-hr330a-03/root
rd.lvm.lv=rhel_ampere-hr330a-03/swap crashkernel=786M cma=1024M

# cat /proc/iomem | grep -i crash
  b0000000-bfffffff : Crash kernel (low)
  bfcbe00000-bffcffffff : Crash kernel

IMO, we should test this feature more before including this in 5.11

Thanks for you test. This behavior is what we what. What is the correct behavior you think?

Besides, this feature is been tested by John and PK, and i test for various parameters.
We may miss something, any comments are welcome.

Thanks,
Chen Zhou

Thanks,
Bhupesh

.