linux-kernel - [PATCH v3 0/2] debugobjects: Allow object pool refill mostly in non-atomic context

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Message-ID: <20250617053527.1223411-1-longman@redhat.com>
Date: Tue, 17 Jun 2025 01:35:25 -0400
From: Waiman Long <longman@...hat.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
	Waiman Long <longman@...hat.com>
Subject: [PATCH v3 0/2] debugobjects: Allow object pool refill mostly in non-atomic context

 v3:
  - Use deferred printk for printing the debug object disable message.
  - Drop the last timer specific memory allocation disablement patch &
    limit memory allocation mostly to non-atomic context instead.

A circular locking dependency was reported by lockdep involving printk()
called from within the memory allocator, console driver with timeout
capability and timer code calling debug_object_activate() doing object
pool refill by allocating memory.

The original approach of disabling memory allocation for timer debug
objects didn't work. Now this series try to limit memory allocation
mostly to non-atomic contexts instead. This will ensure that new object
allocation won't happen in contexts where a spinlock (or a raw spinlock)
has been held or in a non-task context except for the init call, though
a sleeping lock may still be held. This should reduce the chance of
deadlock due to this kind of circular lock dependency.

Waiman Long (2):
  debugobjects: Show the state of debug_objects_enabled
  debugobjects: Allow object pool refill mostly in non-atomic context

 lib/Kconfig.debug  |  1 +
 lib/debugobjects.c | 34 +++++++++++++++++++++++-----------
 2 files changed, 24 insertions(+), 11 deletions(-)

-- 
2.49.0