kernel/lib/debugobjects.c, branch linux-2.6.32.y

debugobjects: Fix boot crash when kmemleak and debugobjects enabled

2011-07-13T03:29:24Z

commit 161b6ae0e067e421b20bb35caf66bdb405c929ac upstream. Order of initialization look like this: ... debugobjects kmemleak ...(lots of other subsystems)... workqueues (through early initcall) ... debugobjects use schedule_work for batch freeing of its data and kmemleak heavily use debugobjects, so when it comes to freeing and workqueues were not initialized yet, kernel crashes: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] __queue_work+0x29/0x41a [] queue_work_on+0x16/0x1d [] queue_work+0x29/0x55 [] schedule_work+0x13/0x15 [] free_object+0x90/0x95 [] debug_check_no_obj_freed+0x187/0x1d3 [] ? _raw_spin_unlock_irqrestore+0x30/0x4d [] ? free_object_rcu+0x68/0x6d [] kmem_cache_free+0x64/0x12c [] free_object_rcu+0x68/0x6d [] __rcu_process_callbacks+0x1b6/0x2d9 ... because system_wq is NULL. Fix it by checking if workqueues susbystem was initialized before using. Signed-off-by: Marcin Slusarz Cc: Catalin Marinas Cc: Tejun Heo Cc: Dipankar Sarma Cc: Paul E. McKenney Link: http://lkml.kernel.org/r/20110528112342.GA3068@joi.lan Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

headers: remove sched.h from interrupt.h

2009-10-11T18:20:58Z

After m68k's task_thread_info() doesn't refer to current, it's possible to remove sched.h from interrupt.h and not break m68k! Many thanks to Heiko Carstens for allowing this. Signed-off-by: Alexey Dobriyan

debugobjects: delay free of internal objects

2009-03-17T11:28:30Z

Impact: avoid recursive kfree calls, less slab activity on heavy load debugobjects checks on kfree whether tracked objects are freed. When a tracked object is freed debugobjects frees the internal reference object as well. The debug object slab cache is marked to not recurse into debugobjects when a slab objects is freed, but the recursive call can be problematic versus locking in the memory allocator. Defer the freeing of debug slab objects via schedule_work. The reasons not to use RCU are: 1) rcu makes the data structure larger 2) there is no real need for rcu as nothing references the obj after we freed it 3) under heavy load it is easier to reuse the to be freed objects instead of allocating new objects from the slab. This lowered the slab activity significantly in a heavy load networking test where lots of timers are created/destroyed. The workqueue based delayed free allows us just to put the to be freed objects back into the object pool and reuse them right away. Signed-off-by: Thomas Gleixner LKML-Reference: <200903162049.58058.nickpiggin@yahoo.com.au>

debugobjects: replace static objects when slab cache becomes available

2009-03-17T11:28:30Z

Impact: refactor/consolidate object management, prepare for delayed free debugobjects allocates static reference objects to track objects which are initialized or activated before the slab cache becomes available. These static reference objects have to be handled seperately in free_object(). The handling of these objects is in the way of implementing a delayed free functionality. The delayed free is required to avoid callbacks into the mm code from debug_check_no_obj_freed(). Replace the static object references with dynamic ones after the slab cache has been initialized. The static objects are now marked initdata. Signed-off-by: Thomas Gleixner LKML-Reference: <200903162049.58058.nickpiggin@yahoo.com.au>

debug_objects: add boot-parameter toggle to turn object debugging off again

2009-03-02T11:04:01Z

While trying to debug why my Atom netbook is falling over booting rawhide debug-enabled kernels, I stumbled across the fact that we've been enabling object debugging by default. However, once you default it to on, you've got no way to turn it back off again at runtime. Add a boolean toggle to turn it off. I would just make it an int module_param, however people may already expect the boolean enable behaviour, so just add an analogue for disabling. Signed-off-by: Kyle McMartin Signed-off-by: Ingo Molnar

debugobjects: add boot parameter default value

2008-11-26T09:07:06Z

Impact: add .config driven boot parameter default value Right now debugobjects can only be activated if the debug_objects boot parameter is passed in via the boot command line. Make this more convenient (and randomizable) by also providing a .config method. Enable it by default. (DEBUG_OBJECTS itself is default-off) Signed-off-by: Ingo Molnar

debugobjects: fix lockdep warning

2008-09-01T07:47:16Z

Daniel J. Blueman reported: > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc4-224c #1 > ------------------------------------------------------- > hald/4680 is trying to acquire lock: > (&n->list_lock){++..}, at: [] add_partial+0x26/0x80 > > but task is already holding lock: > (&obj_hash[i].lock){++..}, at: [] > debug_object_free+0x5c/0x120 We fix it by moving the actual freeing to outside the lock (the lock now only protects the list). The pool lock is also promoted to irq-safe (suggested by Dan). It's necessary because free_pool is now called outside the irq disabled region. So we need to protect against an interrupt handler which calls debug_object_init(). [tglx@linutronix.de: added hlist_move_list helper to avoid looping through the list twice] Reported-by: Daniel J Blueman Signed-off-by: Vegard Nossum Signed-off-by: Thomas Gleixner

Use WARN() in lib/

2008-07-26T19:00:07Z

Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. In addition, one of the if() clauses collapes into the WARN() entirely now. Signed-off-by: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

add a helper function to test if an object is on the stack

2008-07-24T17:47:14Z

lib/debugobjects.c has a function to test if an object is on the stack. The block layer and ide needs it (they need to avoid DMA from/to stack buffers). This patch moves the function to include/linux/sched.h so that everyone can use it. lib/debugobjects.c uses current->stack but this patch uses a task_stack_page() accessor, which is a preferable way to access the stack. Signed-off-by: FUJITA Tomonori Cc: Christoph Lameter Cc: Andy Whitcroft Cc: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

debugobjects: fix lockdep warning

2008-06-18T09:09:54Z

Daniel J Blueman reported: | ======================================================= | [ INFO: possible circular locking dependency detected ] | 2.6.26-rc5-201c #1 | ------------------------------------------------------- | nscd/3669 is trying to acquire lock: | (&n->list_lock){.+..}, at: [] deactivate_slab+0x173/0x1e0 | | but task is already holding lock: | (&obj_hash[i].lock){++..}, at: [] | __debug_object_init+0x2f/0x350 | | which lock already depends on the new lock. There are two locks involved here; the first is a SLUB-local lock, and the second is a debugobjects-local lock. They are basically taken in two different orders: 1. SLUB { debugobjects { ... } } 2. debugobjects { SLUB { ... } } This patch changes pattern #2 by trying to fill the memory pool (e.g. the call into SLUB/kmalloc()) outside the debugobjects lock, so now the two patterns look like this: 1. SLUB { debugobjects { ... } } 2. SLUB { } debugobjects { ... } [ daniel.blueman@gmail.com: pool_lock needs to be taken irq safe in fill_pool ] Reported-by: Daniel J Blueman Signed-off-by: Vegard Nossum Signed-off-by: Thomas Gleixner