Re: [Kernel-packages] [Bug 1665113] [NEW] [Ubuntu 17.04] Kernel panics when large number of hugepages is passed as an boot argument to kernel.

2017-02-15 Thread Michael Hohnbaum 
Leann,

Another one for the Kernel team to track.

 Michael


On 02/15/2017 12:10 PM, Launchpad Bug Tracker wrote:
> bugproxy (bugproxy) has assigned this bug to you for Ubuntu:
>
> Issue:
> ---
> Kernel unable to handle paging request and panic occurs when more number of 
> hugepages is passed as a boot argument to the kernel .
>
> Environment:
> --
> Power NV : Habanaro Bare metal
> OS : Ubuntu 17.04
> Kernel Version : 4.9.0-11-generic
>
> Steps To reproduce:
> ---
>
> 1 - When the ubuntu Kernel boots try to add the boot argument 'hugepages
> = 1200'.
>
> The Kernel Panics and displays call traces like as below.
>
> [5.030274] Unable to handle kernel paging request for data at address 
> 0x
> [5.030323] Faulting instruction address: 0xc0302848
> [5.030366] Oops: Kernel access of bad area, sig: 11 [#1]
> [5.030399] SMP NR_CPUS=2048 [5.030416] NUMA 
> [5.039443] PowerNV
> [5.039461] Modules linked in:
> [5.050091] CPU: 0 PID: 4 Comm: kworker/0:0 Not tainted 4.9.0-11-generic 
> #12-Ubuntu
> [5.053266] Workqueue: events pcpu_balance_workfn
> [5.080647] task: c03c8fe9b800 task.stack: c03ffb118000
> [5.090876] NIP: c0302848 LR: c02709d4 CTR: 
> c016cef0
> [5.094175] REGS: c03ffb11b410 TRAP: 0300   Not tainted  
> (4.9.0-11-generic)
> [5.103040] MSR: 92009033 [
> 5.114466]   CR: 22424222  XER: 
> [5.124932] CFAR: c0008a60 DAR:  DSISR: 4000 
> SOFTE: 1 
> GPR00: c02709d4 c03ffb11b690 c141a400 c03fff50e300 
> GPR04:  024001c2 c03ffb11b780 00219df5 
> GPR08: 003ffb09 c1454fd8   
> GPR12: 4400 c7b6 024001c2 024001c2 
> GPR16: 024001c2   0002 
> GPR20: 000c   024200c0 
> GPR24: c16eef48  c03fff50fd00 024001c2 
> GPR28:  c03fff50fd00 c03fff50e300 c03ffb11b820 
> NIP [c0302848] mem_cgroup_soft_limit_reclaim+0xf8/0x4f0
> [5.213613] LR [c02709d4] do_try_to_free_pages+0x1b4/0x450
> [5.230521] Call Trace:
> [5.230643] [c03ffb11b760] [c02709d4] 
> do_try_to_free_pages+0x1b4/0x450
> [5.254184] [c03ffb11b800] [c0270d68] 
> try_to_free_pages+0xf8/0x270
> [5.281896] [c03ffb11b890] [c0259b88] 
> __alloc_pages_nodemask+0x7a8/0xff0
> [5.321407] [c03ffb11bab0] [c0282cd0] 
> pcpu_populate_chunk+0x110/0x520
> [5.336262] [c03ffb11bb50] [c02841b8] 
> pcpu_balance_workfn+0x758/0x960
> [5.351526] [c03ffb11bc50] [c00ecdd0] 
> process_one_work+0x2b0/0x5a0
> [5.362561] [c03ffb11bce0] [c00ed168] worker_thread+0xa8/0x660
> [5.374007] [c03ffb11bd80] [c00f5320] kthread+0x110/0x130
> [5.385160] [c03ffb11be30] [c000c0e8] 
> ret_from_kernel_thread+0x5c/0x74
> [5.389456] Instruction dump:
> [5.410036] eb81ffe0 eba1ffe8 ebc1fff0 ebe1fff8 4e800020 3d230001 e9499a42 
> 3d220004 
> [5.423598] 3929abd8 794a1f24 7d295214 eac90100  2fa9 
> 419eff74 3b20 
> [5.436503] ---[ end trace 23b650e96be5c549 ]---
> [5.439700] 
>
> This is purely a negative scenario where the system does not have enough
> memory as the hugepages is given a very large argument.
>
> Free output in a system:
> free -h
>   totalusedfree  shared  buff/cache   
> available
> Mem:   251G2.1G248G5.2M502M
> 248G
> Swap:  2.0G159M1.8G
>
> The same scenario when tried after the linux is up like as,
>
> echo 1200 > /proc/sys/vm/nr_hugepages
>
> HugePages_Total:   15069
> HugePages_Free:15069
> HugePages_Rsvd:0
> HugePages_Surp:0
> Hugepagesize:  16384 kB
> root@ltc-haba2:~# free -h
>   totalusedfree  shared  buff/cache   
> available
> Mem:   251G237G 13G5.6M311M 
> 13G
> Swap:  2.0G159M1.8G
>
> In this case the kernel is able to allocate around 237 Gb for hugetlb.
>
> But while the system is booting it gives us panic so please let know if
> this scenario  is expected  to be handled.
>
> I identified the root cause of the panic.
> When the system is running with low memory during mem cgroup initialisation, 
> because most of the page have been grabbed to be huge pages, we hit a chicken 
> and egg issue because when trying to allocate memory for the node's cgroup 
> descriptor, we try to free some memory and in this path cgroup's services are 
> called which assume node's cgroup descriptor is

[Kernel-packages] [Bug 1665113] [NEW] [Ubuntu 17.04] Kernel panics when large number of hugepages is passed as an boot argument to kernel.

2017-02-15 Thread Launchpad Bug Tracker 
You have been subscribed to a public bug:

Issue:
---
Kernel unable to handle paging request and panic occurs when more number of 
hugepages is passed as a boot argument to the kernel .

Environment:
--
Power NV : Habanaro Bare metal
OS : Ubuntu 17.04
Kernel Version : 4.9.0-11-generic

Steps To reproduce:
---

1 - When the ubuntu Kernel boots try to add the boot argument 'hugepages
= 1200'.

The Kernel Panics and displays call traces like as below.

[5.030274] Unable to handle kernel paging request for data at address 
0x
[5.030323] Faulting instruction address: 0xc0302848
[5.030366] Oops: Kernel access of bad area, sig: 11 [#1]
[5.030399] SMP NR_CPUS=2048 [5.030416] NUMA 
[5.039443] PowerNV
[5.039461] Modules linked in:
[5.050091] CPU: 0 PID: 4 Comm: kworker/0:0 Not tainted 4.9.0-11-generic 
#12-Ubuntu
[5.053266] Workqueue: events pcpu_balance_workfn
[5.080647] task: c03c8fe9b800 task.stack: c03ffb118000
[5.090876] NIP: c0302848 LR: c02709d4 CTR: c016cef0
[5.094175] REGS: c03ffb11b410 TRAP: 0300   Not tainted  
(4.9.0-11-generic)
[5.103040] MSR: 92009033 [
5.114466]   CR: 22424222  XER: 
[5.124932] CFAR: c0008a60 DAR:  DSISR: 4000 
SOFTE: 1 
GPR00: c02709d4 c03ffb11b690 c141a400 c03fff50e300 
GPR04:  024001c2 c03ffb11b780 00219df5 
GPR08: 003ffb09 c1454fd8   
GPR12: 4400 c7b6 024001c2 024001c2 
GPR16: 024001c2   0002 
GPR20: 000c   024200c0 
GPR24: c16eef48  c03fff50fd00 024001c2 
GPR28:  c03fff50fd00 c03fff50e300 c03ffb11b820 
NIP [c0302848] mem_cgroup_soft_limit_reclaim+0xf8/0x4f0
[5.213613] LR [c02709d4] do_try_to_free_pages+0x1b4/0x450
[5.230521] Call Trace:
[5.230643] [c03ffb11b760] [c02709d4] 
do_try_to_free_pages+0x1b4/0x450
[5.254184] [c03ffb11b800] [c0270d68] 
try_to_free_pages+0xf8/0x270
[5.281896] [c03ffb11b890] [c0259b88] 
__alloc_pages_nodemask+0x7a8/0xff0
[5.321407] [c03ffb11bab0] [c0282cd0] 
pcpu_populate_chunk+0x110/0x520
[5.336262] [c03ffb11bb50] [c02841b8] 
pcpu_balance_workfn+0x758/0x960
[5.351526] [c03ffb11bc50] [c00ecdd0] 
process_one_work+0x2b0/0x5a0
[5.362561] [c03ffb11bce0] [c00ed168] worker_thread+0xa8/0x660
[5.374007] [c03ffb11bd80] [c00f5320] kthread+0x110/0x130
[5.385160] [c03ffb11be30] [c000c0e8] 
ret_from_kernel_thread+0x5c/0x74
[5.389456] Instruction dump:
[5.410036] eb81ffe0 eba1ffe8 ebc1fff0 ebe1fff8 4e800020 3d230001 e9499a42 
3d220004 
[5.423598] 3929abd8 794a1f24 7d295214 eac90100  2fa9 419eff74 
3b20 
[5.436503] ---[ end trace 23b650e96be5c549 ]---
[5.439700] 

This is purely a negative scenario where the system does not have enough
memory as the hugepages is given a very large argument.

Free output in a system:
free -h
  totalusedfree  shared  buff/cache   available
Mem:   251G2.1G248G5.2M502M248G
Swap:  2.0G159M1.8G

The same scenario when tried after the linux is up like as,

echo 1200 > /proc/sys/vm/nr_hugepages

HugePages_Total:   15069
HugePages_Free:15069
HugePages_Rsvd:0
HugePages_Surp:0
Hugepagesize:  16384 kB
root@ltc-haba2:~# free -h
  totalusedfree  shared  buff/cache   available
Mem:   251G237G 13G5.6M311M 13G
Swap:  2.0G159M1.8G

In this case the kernel is able to allocate around 237 Gb for hugetlb.

But while the system is booting it gives us panic so please let know if
this scenario  is expected  to be handled.

I identified the root cause of the panic.
When the system is running with low memory during mem cgroup initialisation, 
because most of the page have been grabbed to be huge pages, we hit a chicken 
and egg issue because when trying to allocate memory for the node's cgroup 
descriptor, we try to free some memory and in this path cgroup's services are 
called which assume node's cgroup descriptor is allocated.

I'm working on a patch which fixes this panic, but I think it is
expected that the system fail due to OOM when all the pages are assigned
to huge pages.

Patch sent upstream, waiting for review : 
https://patchwork.kernel.org/patch/9573799/

** Affects: linux (Ubuntu)
 Importance: Undecided
 Assignee: Taco Screen team (taco-screen-team)