debugobjects: Use global free list in __debug_check_no_obj_freed()

debugobjects: Use global free list in __debug_check_no_obj_freed()

__debug_check_no_obj_freed() iterates over the to be freed memory region in
chunks and iterates over the corresponding hash bucket list for each
chunk. This can accumulate to hundred thousands of checked objects. In the
worst case this can trigger the soft lockup detector:

NMI watchdog: BUG: soft lockup - CPU#15 stuck for 22s!
CPU: 15 PID: 110342 Comm: stress-ng-getde
Call Trace:
  [<ffffffff8141177e>] debug_check_no_obj_freed+0x13e/0x220
  [<ffffffff811f8751>] __free_pages_ok+0x1f1/0x5c0
  [<ffffffff811fa785>] __free_pages+0x25/0x40
  [<ffffffff812638db>] __free_slab+0x19b/0x270
  [<ffffffff812639e9>] discard_slab+0x39/0x50
  [<ffffffff812679f7>] __slab_free+0x207/0x270
  [<ffffffff81269966>] ___cache_free+0xa6/0xb0
  [<ffffffff8126c267>] qlist_free_all+0x47/0x80
  [<ffffffff8126c5a9>] quarantine_reduce+0x159/0x190
  [<ffffffff8126b3bf>] kasan_kmalloc+0xaf/0xc0
  [<ffffffff8126b8a2>] kasan_slab_alloc+0x12/0x20
  [<ffffffff81265e8a>] kmem_cache_alloc+0xfa/0x360
  [<ffffffff812abc8f>] ? getname_flags+0x4f/0x1f0
  [<ffffffff812abc8f>] getname_flags+0x4f/0x1f0
  [<ffffffff812abe42>] getname+0x12/0x20
  [<ffffffff81298da9>] do_sys_open+0xf9/0x210
  [<ffffffff81298ede>] SyS_open+0x1e/0x20
  [<ffffffff817d6e01>] entry_SYSCALL_64_fastpath+0x1f/0xc2

The code path might be called in either atomic or non-atomic context, but
in_atomic() can't tell if the current context is atomic or not on a
PREEMPT=n kernel, so cond_resched() can't be used to prevent the
softlockup.

Utilize the global free list to shorten the loop execution time.

[ tglx: Massaged changelog ]

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: longman@redhat.com
Link: https://lkml.kernel.org/r/1517872708-24207-5-git-send-email-yang.shi@linux.alibaba.com