commit ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in
objects") initializes stack depot while creating cache if SLAB_STORE_USER
flag is set.
This can make kernel crash because a cache can be created in various
contexts. For example if user sets slub_debug=U, kernel crashes
because create_boot_cache() calls stack_depot_init(), which tries to
allocate hash table using memblock_alloc() if slab is not available.
But memblock is also not available at that time.
This patch solves the problem by initializing stack depot early
in boot process if SLAB_STORE_USER debug flag is set globally
or the flag is set to at least one cache.
[ elver@xxxxxxxxxx: initialize stack depot depending on slub_debug
parameter instead of allowing stack_depot_init() can be called
in kmem_cache_init() for simplicity. ]
Link: https://lkml.org/lkml/2022/2/28/238
Fixes: ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in objects")
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
---
include/linux/slab.h | 1 +
init/main.c | 1 +
mm/slab.c | 4 ++++
mm/slob.c | 4 ++++
mm/slub.c | 28 +++++++++++++++++++++++++---
5 files changed, 35 insertions(+), 3 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 37bde99b74af..023f3f71ae35 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -139,6 +139,7 @@ struct mem_cgroup;
/*
* struct kmem_cache related prototypes
*/
+void __init kmem_cache_init_early(void);
void __init kmem_cache_init(void);
bool slab_is_available(void);
diff --git a/init/main.c b/init/main.c
index 65fa2e41a9c0..4fdb7975a085 100644
--- a/init/main.c
+++ b/init/main.c
@@ -835,6 +835,7 @@ static void __init mm_init(void)
kfence_alloc_pool();
report_meminit();
stack_depot_early_init();
+ kmem_cache_init_early();
mem_init();
mem_init_print_info();
kmem_cache_init();
diff --git a/mm/slab.c b/mm/slab.c
index ddf5737c63d9..80a6d01aab06 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1196,6 +1196,10 @@ static void __init set_up_node(struct kmem_cache *cachep, int index)
}
}
+void __init kmem_cache_init_early(void)
+{
+}
+
/*
* Initialisation. Called after the page allocator have been initialised and
* before smp_init().
diff --git a/mm/slob.c b/mm/slob.c
index 60c5842215f1..00e323af8be4 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -715,6 +715,10 @@ struct kmem_cache kmem_cache_boot = {
.align = ARCH_KMALLOC_MINALIGN,
};
+void __init kmem_cache_init_early(void)
+{
+}
+
void __init kmem_cache_init(void)
{
kmem_cache = &kmem_cache_boot;
diff --git a/mm/slub.c b/mm/slub.c
index a74afe59a403..40bcd18143b6 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4221,9 +4221,6 @@ static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
s->remote_node_defrag_ratio = 1000;
#endif
- if (s->flags & SLAB_STORE_USER && IS_ENABLED(CONFIG_STACKDEPOT))
- stack_depot_init();
-
/* Initialize the pre-computed randomized freelist if slab is up */
if (slab_state >= UP) {
if (init_cache_random_seq(s))
@@ -4810,6 +4807,31 @@ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
return s;
}
+/* Initialize stack depot if needed */
+void __init kmem_cache_init_early(void)
+{
+#ifdef CONFIG_STACKDEPOT
+ slab_flags_t block_flags;
+ char *next_block;
+ char *slab_list;
+
+ if (slub_debug & SLAB_STORE_USER)
+ goto init_stack_depot;
+
+ next_block = slub_debug_string;
+ while (next_block) {
+ next_block = parse_slub_debug_flags(next_block, &block_flags, &slab_list, false);
+ if (block_flags & SLAB_STORE_USER)
+ goto init_stack_depot;
+ }
+
+ return;
+
+init_stack_depot:
+ stack_depot_init();
+#endif
+}
+
void __init kmem_cache_init(void)
{
static __initdata struct kmem_cache boot_kmem_cache,
--
2.33.1
