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x86/unwinder/guess: Prevent using CONFIG_UNWINDER_GUESS=y with CONFIG_STACKDEPOT=y

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Stackdepot doesn't work well with CONFIG_UNWINDER_GUESS=y.
The 'guess' unwinder generate awfully large and inaccurate stacktraces,
thus stackdepot can't deduplicate stacktraces because they all look like
unique. Eventually stackdepot reaches its capacity limit:

  WARNING: CPU: 0 PID: 545 at lib/stackdepot.c:119 depot_save_stack+0x28e/0x550
  Call Trace:
   ? kasan_kmalloc+0x144/0x160
   ? depot_save_stack+0x1f5/0x550
   ? do_raw_spin_unlock+0xda/0xf0
   ? preempt_count_sub+0x13/0xc0

  <...90 lines...>

   ? do_raw_spin_unlock+0xda/0xf0

Add a STACKDEPOT=n dependency to UNWINDER_GUESS to avoid the problem.

Reported-by: kernel test robot <xiaolong.ye@intel.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171130123554.4330-1-aryabinin@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andrey Ryabinin 2017-11-30 15:35:54 +03:00 committed by Ingo Molnar
parent f79ce87fa4
commit 0a373d4fc2
1 changed files with 1 additions and 0 deletions
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arch/x86/Kconfig.debug
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@ -400,6 +400,7 @@ config UNWINDER_FRAME_POINTER
config UNWINDER_GUESS config UNWINDER_GUESS
bool "Guess unwinder" bool "Guess unwinder"
depends on EXPERT depends on EXPERT
depends on !STACKDEPOT
---help--- ---help---
This option enables the "guess" unwinder for unwinding kernel stack This option enables the "guess" unwinder for unwinding kernel stack
traces. It scans the stack and reports every kernel text address it traces. It scans the stack and reports every kernel text address it