From dd9dbeec7444b13b510dc4a863e9593d1799f965 Mon Sep 17 00:00:00 2001 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> Date: Tue, 1 Mar 2022 03:36:38 +0000 Subject: [PATCH] mm/slub: initialize stack depot in boot process commit ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in objects") initializes stack depot in cache creation if SLAB_STORE_USER flag is set. This can make kernel crash because a cache can be crashed 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 for at least one cache. [ elver@google.com: initialize stack depot depending on slub_debug parameter instead of allowing stack_depot_init() to be called during kmem_cache_init() for simplicity. ] [ vbabka@suse.cz: parse slub_debug parameter in setup_slub_debug() and initialize stack depot in stack_depot_early_init(). ] Link: https://lore.kernel.org/all/YhyeaP8lrzKgKm5A@ip-172-31-19-208.ap-northeast-1.compute.internal/ Fixes: ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in objects") Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- include/linux/slab.h | 6 ++++++ include/linux/stackdepot.h | 3 ++- mm/slub.c | 18 +++++++++++++++--- 3 files changed, 23 insertions(+), 4 deletions(-) diff --git a/include/linux/slab.h b/include/linux/slab.h index 37bde99b74af09..062128e0db1003 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -763,6 +763,12 @@ extern void kvfree_sensitive(const void *addr, size_t len); unsigned int kmem_cache_size(struct kmem_cache *s); void __init kmem_cache_init_late(void); +#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_STACKDEPOT) +int slab_stack_depot_init(void); +#else +int slab_stack_depot_init(void) { return 0; } +#endif + #if defined(CONFIG_SMP) && defined(CONFIG_SLAB) int slab_prepare_cpu(unsigned int cpu); int slab_dead_cpu(unsigned int cpu); diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h index 17f992fe6355b6..a813a2673c480c 100644 --- a/include/linux/stackdepot.h +++ b/include/linux/stackdepot.h @@ -12,6 +12,7 @@ #define _LINUX_STACKDEPOT_H #include +#include typedef u32 depot_stack_handle_t; @@ -32,7 +33,7 @@ int stack_depot_init(void); #ifdef CONFIG_STACKDEPOT_ALWAYS_INIT static inline int stack_depot_early_init(void) { return stack_depot_init(); } #else -static inline int stack_depot_early_init(void) { return 0; } +static inline int stack_depot_early_init(void) { return slab_stack_depot_init(); } #endif depot_stack_handle_t stack_depot_save(unsigned long *entries, diff --git a/mm/slub.c b/mm/slub.c index a74afe59a40381..2419fc3cc9f32c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -646,6 +646,14 @@ static slab_flags_t slub_debug; static char *slub_debug_string; static int disable_higher_order_debug; +static bool init_stack_depot; + +int slab_stack_depot_init(void) +{ + if (init_stack_depot) + stack_depot_init(); + return 0; +} /* * slub is about to manipulate internal object metadata. This memory lies @@ -1531,6 +1539,8 @@ static int __init setup_slub_debug(char *str) global_slub_debug_changed = true; } else { slab_list_specified = true; + if (flags & SLAB_STORE_USER) + init_stack_depot = true; } } @@ -1546,6 +1556,10 @@ static int __init setup_slub_debug(char *str) global_flags = slub_debug; slub_debug_string = saved_str; } + + if (global_flags & SLAB_STORE_USER) + init_stack_depot = true; + out: slub_debug = global_flags; if (slub_debug != 0 || slub_debug_string) @@ -1556,6 +1570,7 @@ static int __init setup_slub_debug(char *str) static_branch_unlikely(&init_on_free)) && (slub_debug & SLAB_POISON)) pr_info("mem auto-init: SLAB_POISON will take precedence over init_on_alloc/init_on_free\n"); + return 1; } @@ -4221,9 +4236,6 @@ 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))