kernel-packages team mailing list archive

[dann frazier <dann.frazier@xxxxxxxxxxxxx>]

** Description changed:

+ [Impact]
+ A kernel WARNING is printed on boot on arm64:
+ 
  [    0.000000] ------------[ cut here ]------------
  [    0.000000] WARNING: CPU: 0 PID: 0 at /build/linux-vmnY7Y/linux-4.2.0/arch/arm64/mm/numa.c:449 numa_init+0x90/0x398()
  [    0.000000] Modules linked in:
  [    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.2.0-16-generic #19-Ubuntu
  [    0.000000] Hardware name: APM X-Gene Merlin board (DT)
  [    0.000000] Call trace:
  [    0.000000] [<ffffffc00008ab90>] dump_backtrace+0x0/0x178
  [    0.000000] [<ffffffc00008ad28>] show_stack+0x20/0x30
  [    0.000000] [<ffffffc0008a41d8>] dump_stack+0x7c/0x98
  [    0.000000] [<ffffffc0000bf9e8>] warn_slowpath_common+0xa0/0xe0
  [    0.000000] [<ffffffc0000bfbb0>] warn_slowpath_null+0x38/0x50
  [    0.000000] [<ffffffc000c3de84>] numa_init+0x8c/0x398
  [    0.000000] [<ffffffc000c3e1c0>] arm64_numa_init+0x30/0x40
  [    0.000000] [<ffffffc000c3ce20>] bootmem_init+0x74/0x12c
  [    0.000000] [<ffffffc000c3d5b0>] paging_init+0x198/0x224
  [    0.000000] [<ffffffc000c3a028>] setup_arch+0x284/0x624
  [    0.000000] [<ffffffc000c36718>] start_kernel+0xf0/0x424
  [    0.000000] ---[ end trace f24b6c88ae00fa9a ]---
+ 
+ Though it is believed to be innocuous, it isn't obviously so, and will
+ likely scare users.
+ 
+ [Test Case]
+ Boot wily on an arm64 system and look for the above trace in dmesg.
+ 
+ [Regression Risk]
+ The NUMA patches for arm64 were merged in in preparation for a hardware enablement project that was later postponed. I'm very confident that there are no systems out there that can boot wily's kernel and benefit from these patches.

** Also affects: linux (Ubuntu Wily)
   Importance: Undecided
       Status: New

** Changed in: linux (Ubuntu Wily)
       Status: New => In Progress

** Changed in: linux (Ubuntu Wily)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: linux (Ubuntu)
       Status: Confirmed => Invalid

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https://bugs.launchpad.net/bugs/1509221

Title:
  wily: arm64: warning in numa_init() during booting

Status in linux package in Ubuntu:
  Invalid
Status in linux source package in Wily:
  In Progress

Bug description:
  [Impact]
  A kernel WARNING is printed on boot on arm64:

  [    0.000000] ------------[ cut here ]------------
  [    0.000000] WARNING: CPU: 0 PID: 0 at /build/linux-vmnY7Y/linux-4.2.0/arch/arm64/mm/numa.c:449 numa_init+0x90/0x398()
  [    0.000000] Modules linked in:
  [    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.2.0-16-generic #19-Ubuntu
  [    0.000000] Hardware name: APM X-Gene Merlin board (DT)
  [    0.000000] Call trace:
  [    0.000000] [<ffffffc00008ab90>] dump_backtrace+0x0/0x178
  [    0.000000] [<ffffffc00008ad28>] show_stack+0x20/0x30
  [    0.000000] [<ffffffc0008a41d8>] dump_stack+0x7c/0x98
  [    0.000000] [<ffffffc0000bf9e8>] warn_slowpath_common+0xa0/0xe0
  [    0.000000] [<ffffffc0000bfbb0>] warn_slowpath_null+0x38/0x50
  [    0.000000] [<ffffffc000c3de84>] numa_init+0x8c/0x398
  [    0.000000] [<ffffffc000c3e1c0>] arm64_numa_init+0x30/0x40
  [    0.000000] [<ffffffc000c3ce20>] bootmem_init+0x74/0x12c
  [    0.000000] [<ffffffc000c3d5b0>] paging_init+0x198/0x224
  [    0.000000] [<ffffffc000c3a028>] setup_arch+0x284/0x624
  [    0.000000] [<ffffffc000c36718>] start_kernel+0xf0/0x424
  [    0.000000] ---[ end trace f24b6c88ae00fa9a ]---

  Though it is believed to be innocuous, it isn't obviously so, and will
  likely scare users.

  [Test Case]
  Boot wily on an arm64 system and look for the above trace in dmesg.

  [Regression Risk]
  The NUMA patches for arm64 were merged in in preparation for a hardware enablement project that was later postponed. I'm very confident that there are no systems out there that can boot wily's kernel and benefit from these patches.

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