Commit 11ac25c6 authored by Marco Elver's avatar Marco Elver Committed by Linus Torvalds
Browse files

lib/stackdepot: introduce __stack_depot_save() 

Add __stack_depot_save(), which provides more fine-grained control over
stackdepot's memory allocation behaviour, in case stackdepot runs out of
"stack slabs".

Normally stackdepot uses alloc_pages() in case it runs out of space;
passing can_alloc==false to __stack_depot_save() prohibits this, at the
cost of more likely failure to record a stack trace.

Link: https://lkml.kernel.org/r/20210913112609.2651084-4-elver@google.com


Signed-off-by: default avatarMarco Elver <elver@google.com>
Tested-by: default avatarShuah Khan <skhan@linuxfoundation.org>
Acked-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: default avatarAndrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Taras Madan <tarasmadan@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Walter Wu <walter-zh.wu@mediatek.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7f2b8818

include/linux/stackdepot.h

+4 −0
Original line number Diff line number Diff line
@@ -15,6 +15,10 @@ 


typedef u32 depot_stack_handle_t;



depot_stack_handle_t __stack_depot_save(unsigned long *entries,

					unsigned int nr_entries,

					gfp_t gfp_flags, bool can_alloc);



depot_stack_handle_t stack_depot_save(unsigned long *entries,

				      unsigned int nr_entries, gfp_t gfp_flags);

lib/stackdepot.c

+37 −6
Original line number Diff line number Diff line
@@ -248,17 +248,28 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, 
EXPORT_SYMBOL_GPL(stack_depot_fetch);



/**

 * stack_depot_save - Save a stack trace from an array

 * __stack_depot_save - Save a stack trace from an array

 *

 * @entries:		Pointer to storage array

 * @nr_entries:		Size of the storage array

 * @alloc_flags:	Allocation gfp flags

 * @can_alloc:		Allocate stack slabs (increased chance of failure if false)

 *

 * Saves a stack trace from @entries array of size @nr_entries. If @can_alloc is

 * %true, is allowed to replenish the stack slab pool in case no space is left

 * (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, avoids

 * any allocations and will fail if no space is left to store the stack trace.

 *

 * Context: Any context, but setting @can_alloc to %false is required if

 *          alloc_pages() cannot be used from the current context. Currently

 *          this is the case from contexts where neither %GFP_ATOMIC nor

 *          %GFP_NOWAIT can be used (NMI, raw_spin_lock).

 *

 * Return: The handle of the stack struct stored in depot

 * Return: The handle of the stack struct stored in depot, 0 on failure.

 */

depot_stack_handle_t stack_depot_save(unsigned long *entries,

depot_stack_handle_t __stack_depot_save(unsigned long *entries,

					unsigned int nr_entries,

				      gfp_t alloc_flags)

					gfp_t alloc_flags, bool can_alloc)

{

	struct stack_record *found = NULL, **bucket;

	depot_stack_handle_t retval = 0;
@@ -291,7 +302,7 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries, 
	 * The smp_load_acquire() here pairs with smp_store_release() to

	 * |next_slab_inited| in depot_alloc_stack() and init_stack_slab().

	 */

	if (unlikely(!smp_load_acquire(&next_slab_inited))) {

	if (unlikely(can_alloc && !smp_load_acquire(&next_slab_inited))) {

		/*

		 * Zero out zone modifiers, as we don't have specific zone

		 * requirements. Keep the flags related to allocation in atomic
@@ -339,6 +350,26 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries, 
fast_exit:

	return retval;

}

EXPORT_SYMBOL_GPL(__stack_depot_save);



/**

 * stack_depot_save - Save a stack trace from an array

 *

 * @entries:		Pointer to storage array

 * @nr_entries:		Size of the storage array

 * @alloc_flags:	Allocation gfp flags

 *

 * Context: Contexts where allocations via alloc_pages() are allowed.

 *          See __stack_depot_save() for more details.

 *

 * Return: The handle of the stack struct stored in depot, 0 on failure.

 */

depot_stack_handle_t stack_depot_save(unsigned long *entries,

				      unsigned int nr_entries,

				      gfp_t alloc_flags)

{

	return __stack_depot_save(entries, nr_entries, alloc_flags, true);

}

EXPORT_SYMBOL_GPL(stack_depot_save);



static inline int in_irqentry_text(unsigned long ptr)