[PATCH v7 00/70] Introducing the Maple Tree

[Yu Zhao]

On Tue, Apr 19, 2022 at 9:51 AM Liam Howlett <liam.howlett at oracle.com> wrote:
>
> * Yu Zhao <yuzhao at google.com> [220416 15:30]:
> > On Sat, Apr 16, 2022 at 9:19 AM Liam Howlett <liam.howlett at oracle.com> wrote:
> > >
> >
> > <snipped>
> >
> > > How did you hit this issue?  Just on boot?
> >
> > I was hoping this is known to you or you have something I can verify for you.
>
>
> Thanks, yes.  I believe that both crashes are the same root cause.  The
> cause is that I was not cleaning up after the kmem bulk allocation
> failure on my side.  Please test with this patch.

Thanks. I applied this patch and hit a LOCKDEP and then a BUG_ON:

  lib/maple_tree.c:847 suspicious rcu_dereference_protected() usage!
  Call Trace:
   <TASK>
   dump_stack_lvl+0x6c/0x9a
   dump_stack+0x10/0x12
   lockdep_rcu_suspicious+0x12c/0x140
   __mt_destroy+0x96/0xd0
   exit_mmap+0x2a0/0x360
   __mmput+0x34/0x100
   mmput+0x2f/0x40
   free_bprm+0x64/0xe0
   kernel_execve+0x129/0x330
   call_usermodehelper_exec_async+0xd8/0x130
   ? proc_cap_handler+0x210/0x210
   ret_from_fork+0x1f/0x30
   </TASK>

  BUG: unable to handle page fault for address: ffffa6072aff0060
  RIP: 0010:mab_calc_split+0x103/0x1a0
  Code: 29 c1 8b 86 64 02 00 00 0f b6 80 dc 7d a7 96 39 c1 7e 05 83 c3
01 eb 06 81 c3 ff 00 00 00 0f b6 c3 45 84 d2 74 3f 41 0f b6 ca <48> 83
bc ce 10 01 00 00 00 75 2d 41 83 c0 ff 41 39 c8 7e 20 0f b6
  RSP: 0018:ffffa6072afef6d0 EFLAGS: 00010286
  RAX: 0000000000000054 RBX: 0000000000000154 RCX: 00000000000000aa
  RDX: ffffa6072afef83f RSI: ffffa6072afefa00 RDI: ffffa6072afefe80
  RBP: ffffa6072afef6e0 R08: 0000000000000010 R09: 00000000000000ff
  R10: 00000000000000aa R11: 0000000000000001 R12: 00000000000000ff
  R13: ffffa6072afefa00 R14: ffffa6072afef9c0 R15: 0000000000000008
  FS:  0000000001d75340(0000) GS:ffff8a56bf980000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffffa6072aff0060 CR3: 00000004986ca002 CR4: 00000000001706e0
  Call Trace:
   <TASK>
   mas_spanning_rebalance+0x416/0x2060
   mas_wr_store_entry+0xa6d/0xa80
   mas_store_gfp+0xf6/0x170
   do_mas_align_munmap+0x32b/0x5c0
   do_mas_munmap+0xf3/0x110
   __vm_munmap+0xd4/0x180
   __x64_sys_munmap+0x1b/0x20
   do_syscall_64+0x44/0xa0

$ ./scripts/faddr2line vmlinux mab_calc_split+0x103
mab_calc_split+0x103/0x1a0:
mab_no_null_split at lib/maple_tree.c:1787
(inlined by) mab_calc_split at lib/maple_tree.c:1866