Re: [PATCH v12 1/9] hugetlb_cgroup: Add hugetlb_cgroup reservation counter

[Mina Almasry]

On Tue, Feb 18, 2020 at 6:21 AM Qian Cai <cai@xxxxxx> wrote:
>
> On Tue, 2020-02-11 at 15:19 -0800, Andrew Morton wrote:
> > On Tue, 11 Feb 2020 13:31:20 -0800 Mina Almasry <almasrymina@xxxxxxxxxx> wrote:
> >
> > > These counters will track hugetlb reservations rather than hugetlb
> > > memory faulted in. This patch only adds the counter, following patches
> > > add the charging and uncharging of the counter.
> >
> > We're still pretty thin on review here, but as it's v12 and Mike
> > appears to be signed up to look at this work, I'll add them to -next to
> > help move things forward.
> >
>
> Reverted the whole series on the top of next-20200217 fixed a crash below (I
> don't see anything in next-20200218 would make any differences).
>
> [ 7933.691114][T35046] LTP: starting hugemmap06
> [ 7933.806377][T14355] ------------[ cut here ]------------
> [ 7933.806541][T14355] kernel BUG at mm/hugetlb.c:490!
> VM_BUG_ON(t - f <= 1);
> [ 7933.806562][T14355] Oops: Exception in kernel mode, sig: 5 [#1]
> [ 7933.806573][T14355] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256
> DEBUG_PAGEALLOC NUMA PowerNV
> [ 7933.806594][T14355] Modules linked in: kvm_hv kvm brd ext4 crc16 mbcache jbd2
> loop ip_tables x_tables xfs sd_mod bnx2x ahci mdio libahci tg3 libata libphy
> firmware_class dm_mirror dm_region_hash dm_log dm_mod [last unloaded:
> binfmt_misc]
> [ 7933.806651][T14355] CPU: 54 PID: 14355 Comm: hugemmap06 Tainted:
> G           O      5.6.0-rc2-next-20200217 #1
> [ 7933.806674][T14355] NIP:  c00000000040d22c LR: c00000000040d210 CTR:
> 0000000000000000
> [ 7933.806696][T14355] REGS: c0000014b71ef660 TRAP: 0700   Tainted:
> G           O       (5.6.0-rc2-next-20200217)
> [ 7933.806727][T14355] MSR:  900000000282b033
> <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 22022228  XER: 00000000
> [ 7933.806772][T14355] CFAR: c00000000040cbec IRQMASK: 0
> [ 7933.806772][T14355] GPR00: c00000000040d210 c0000014b71ef8f0 c000000001657000
> 0000000000000001
> [ 7933.806772][T14355] GPR04: 0000000000000012 0000000000000013 0000000000000000
> 0000000000000000
> [ 7933.806772][T14355] GPR08: 0000000000000002 0000000000000002 0000000000000001
> 0000000000000036
> [ 7933.806772][T14355] GPR12: 0000000022022222 c000001ffffd3d00 00007fffad670000
> 00007fffa4bc0000
> [ 7933.806772][T14355] GPR16: 0000000000000000 c000000001567178 c0000014b71efa50
> 0000000000000000
> [ 7933.806772][T14355] GPR20: 0000000000000000 0000000000000013 0000000000000012
> 0000000000000001
> [ 7933.806772][T14355] GPR24: c0000019f74cd270 5deadbeef0000100 5deadbeef0000122
> c0000019f74cd2c0
> [ 7933.806772][T14355] GPR28: 0000000000000001 c0000019f74cd268 c0000014b71ef918
> 0000000000000001
> [ 7933.806961][T14355] NIP [c00000000040d22c] region_add+0x11c/0x3a0
> [ 7933.806980][T14355] LR [c00000000040d210] region_add+0x100/0x3a0
> [ 7933.807008][T14355] Call Trace:
> [ 7933.807024][T14355] [c0000014b71ef8f0] [c00000000040d210]
> region_add+0x100/0x3a0 (unreliable)
> [ 7933.807056][T14355] [c0000014b71ef9b0] [c00000000040e0c8]
> __vma_reservation_common+0x148/0x210
> __vma_reservation_common at mm/hugetlb.c:2150
> [ 7933.807087][T14355] [c0000014b71efa20] [c0000000004132a0]
> alloc_huge_page+0x350/0x830
> alloc_huge_page at mm/hugetlb.c:2359
> [ 7933.807100][T14355] [c0000014b71efad0] [c0000000004168f8]
> hugetlb_no_page+0x158/0xcb0
> [ 7933.807113][T14355] [c0000014b71efc20] [c000000000417bc8]
> hugetlb_fault+0x678/0xb30
> [ 7933.807136][T14355] [c0000014b71efcd0] [c0000000003b1de4]
> handle_mm_fault+0x444/0x450
> [ 7933.807158][T14355] [c0000014b71efd20] [c000000000070b1c]
> __do_page_fault+0x2bc/0xfd0
> [ 7933.807181][T14355] [c0000014b71efe20] [c00000000000aa88]
> handle_page_fault+0x10/0x30
> [ 7933.807201][T14355] Instruction dump:
> [ 7933.807209][T14355] 38c00000 7ea5ab78 7ec4b378 7fa3eb78 4bfff80d e9210020
> e91d0050 e95d0068
> [ 7933.807232][T14355] 7d3c4850 7d294214 7faa4800 409c0238 <0b170000> 7f03c378
> 4858c005 60000000
> [ 7933.807267][T14355] ---[ end trace 7560275de5f409f8 ]---
> [ 7933.905258][T14355]
> [ 7934.905339][T14355] Kernel panic - not syncing: Fatal exception

Hi Qian,

Yes this VM_BUG_ON was added by a patch in the series ("hugetlb:
disable region_add file_region coalescing") so it's definitely related
to the series. I'm taking a look at why this VM_BUG_ON fires. Can you
confirm you reproduce this by running hugemmap06 from the ltp on a
powerpc machine? Can I maybe have your config?

Thanks!