kasan: don't call find_vm_area() in a PREEMPT_RT kernel

The following bug report was found when running a PREEMPT_RT debug kernel.

 BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 140605, name: kunit_try_catch
 preempt_count: 1, expected: 0

 Call trace:
  rt_spin_lock+0x70/0x140
  find_vmap_area+0x84/0x168
  find_vm_area+0x1c/0x50
  print_address_description.constprop.0+0x2a0/0x320
  print_report+0x108/0x1f8
  kasan_report+0x90/0xc8

Since commit e30a0361b851 ("kasan: make report_lock a raw spinlock"),
report_lock was changed to raw_spinlock_t to fix another similar
PREEMPT_RT problem.  That alone isn't enough to cover other corner cases.

print_address_description() is always invoked under the report_lock.  The
context under this lock is always atomic even on PREEMPT_RT. 
find_vm_area() acquires vmap_node::busy.lock which is a spinlock_t,
becoming a sleeping lock on PREEMPT_RT and must not be acquired in atomic
context.

Don't invoke find_vm_area() on PREEMPT_RT and just print the address. 
Non-PREEMPT_RT builds remain unchanged.  Add a DEFINE_WAIT_OVERRIDE_MAP()
macro to tell lockdep that this lock nesting is allowed because the
PREEMPT_RT part (which is invalid) has been taken care of.  This macro was
first introduced in commit 0cce06ba859a ("debugobjects,locking: Annotate
debug_object_fill_pool() wait type violation").

Link: https://lkml.kernel.org/r/[email protected]
Fixes: e30a0361b851 ("kasan: make report_lock a raw spinlock")
Signed-off-by: Waiman Long <[email protected]>
Suggested-by: Andrey Konovalov <[email protected]>
Reviewed-by: Andrey Konovalov <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Dmitriy Vyukov <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Mariano Pache <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Vincenzo Frascino <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions