Commit c4cf6785 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Vlastimil Babka
Browse files

mm/slub: Move the stackdepot related allocation out of IRQ-off section. 



The set_track() invocation in free_debug_processing() is invoked with
acquired slab_lock(). The lock disables interrupts on PREEMPT_RT and
this forbids to allocate memory which is done in stack_depot_save().

Split set_track() into two parts: set_track_prepare() which allocate
memory and set_track_update() which only performs the assignment of the
trace data structure. Use set_track_prepare() before disabling
interrupts.

[ vbabka@suse.cz: make set_track() call set_track_update() instead of
  open-coded assignments ]

Fixes: 5cf909c5 ("mm/slub: use stackdepot to save stack trace in objects")
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Link: https://lore.kernel.org/r/Yp9sqoUi4fVa5ExF@linutronix.de
parent b13baccc

mm/slub.c

+34 −7
Original line number Diff line number Diff line
@@ -726,25 +726,48 @@ static struct track *get_track(struct kmem_cache *s, void *object, 
	return kasan_reset_tag(p + alloc);

}



static void noinline set_track(struct kmem_cache *s, void *object,

			enum track_item alloc, unsigned long addr)

{

	struct track *p = get_track(s, object, alloc);



#ifdef CONFIG_STACKDEPOT

static noinline depot_stack_handle_t set_track_prepare(void)

{

	depot_stack_handle_t handle;

	unsigned long entries[TRACK_ADDRS_COUNT];

	unsigned int nr_entries;



	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);

	p->handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);

	handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);



	return handle;

}

#else

static inline depot_stack_handle_t set_track_prepare(void)

{

	return 0;

}

#endif



static void set_track_update(struct kmem_cache *s, void *object,

			     enum track_item alloc, unsigned long addr,

			     depot_stack_handle_t handle)

{

	struct track *p = get_track(s, object, alloc);



#ifdef CONFIG_STACKDEPOT

	p->handle = handle;

#endif

	p->addr = addr;

	p->cpu = smp_processor_id();

	p->pid = current->pid;

	p->when = jiffies;

}



static __always_inline void set_track(struct kmem_cache *s, void *object,

				      enum track_item alloc, unsigned long addr)

{

	depot_stack_handle_t handle = set_track_prepare();



	set_track_update(s, object, alloc, addr, handle);

}



static void init_tracking(struct kmem_cache *s, void *object)

{

	struct track *p;
@@ -1373,6 +1396,10 @@ static noinline int free_debug_processing( 
	int cnt = 0;

	unsigned long flags, flags2;

	int ret = 0;

	depot_stack_handle_t handle = 0;



	if (s->flags & SLAB_STORE_USER)

		handle = set_track_prepare();



	spin_lock_irqsave(&n->list_lock, flags);

	slab_lock(slab, &flags2);
@@ -1391,7 +1418,7 @@ static noinline int free_debug_processing( 
	}



	if (s->flags & SLAB_STORE_USER)

		set_track(s, object, TRACK_FREE, addr);

		set_track_update(s, object, TRACK_FREE, addr, handle);

	trace(s, slab, object, 0);

	/* Freepointer not overwritten by init_object(), SLAB_POISON moved it */

	init_object(s, object, SLUB_RED_INACTIVE);