From: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx> Subject: lib: stackdepot: add support to disable stack depot Add a kernel parameter stack_depot_disable to disable stack depot. So that stack hash table doesn't consume any memory when stack depot is disabled. The use case is CONFIG_PAGE_OWNER without page_owner=on. Without this patch, stackdepot will consume the memory for the hashtable. By default, it's 8M which is never trivial. With this option, in CONFIG_PAGE_OWNER configured system, page_owner=off, stack_depot_disable in kernel command line, we could save the wasted memory for the hashtable. [akpm@xxxxxxxxxxxxxxxxxxxx: fix CONFIG_STACKDEPOT=n build] Link: https://lkml.kernel.org/r/1611749198-24316-2-git-send-email-vjitta@xxxxxxxxxxxxxx Signed-off-by: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx> Signed-off-by: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Yogesh Lal <ylal@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/admin-guide/kernel-parameters.txt | 6 ++ include/linux/stackdepot.h | 9 +++ init/main.c | 2 lib/stackdepot.c | 32 ++++++++++++-- 4 files changed, 45 insertions(+), 4 deletions(-) --- a/Documentation/admin-guide/kernel-parameters.txt~lib-stackdepot-add-support-to-disable-stack-depot +++ a/Documentation/admin-guide/kernel-parameters.txt @@ -5182,6 +5182,12 @@ growing up) the main stack are reserved for no other mapping. Default value is 256 pages. + stack_depot_disable= [KNL] + Setting this to true through kernel command line will + disable the stack depot thereby saving the static memory + consumed by the stack hash table. By default this is set + to false. + stacktrace [FTRACE] Enabled the stack tracer on boot up. --- a/include/linux/stackdepot.h~lib-stackdepot-add-support-to-disable-stack-depot +++ a/include/linux/stackdepot.h @@ -21,4 +21,13 @@ unsigned int stack_depot_fetch(depot_sta unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries); +#ifdef CONFIG_STACKDEPOT +int stack_depot_init(void); +#else +static inline int stack_depot_init(void) +{ + return 0; +} +#endif /* CONFIG_STACKDEPOT */ + #endif --- a/init/main.c~lib-stackdepot-add-support-to-disable-stack-depot +++ a/init/main.c @@ -97,6 +97,7 @@ #include <linux/mem_encrypt.h> #include <linux/kcsan.h> #include <linux/init_syscalls.h> +#include <linux/stackdepot.h> #include <asm/io.h> #include <asm/bugs.h> @@ -827,6 +828,7 @@ static void __init mm_init(void) init_mem_debugging_and_hardening(); kfence_alloc_pool(); report_meminit(); + stack_depot_init(); mem_init(); /* page_owner must be initialized after buddy is ready */ page_ext_init_flatmem_late(); --- a/lib/stackdepot.c~lib-stackdepot-add-support-to-disable-stack-depot +++ a/lib/stackdepot.c @@ -31,6 +31,7 @@ #include <linux/stackdepot.h> #include <linux/string.h> #include <linux/types.h> +#include <linux/memblock.h> #define DEPOT_STACK_BITS (sizeof(depot_stack_handle_t) * 8) @@ -145,9 +146,32 @@ static struct stack_record *depot_alloc_ #define STACK_HASH_MASK (STACK_HASH_SIZE - 1) #define STACK_HASH_SEED 0x9747b28c -static struct stack_record *stack_table[STACK_HASH_SIZE] = { - [0 ... STACK_HASH_SIZE - 1] = NULL -}; +static bool stack_depot_disable; +static struct stack_record **stack_table; + +static int __init is_stack_depot_disabled(char *str) +{ + kstrtobool(str, &stack_depot_disable); + if (stack_depot_disable) { + pr_info("Stack Depot is disabled\n"); + stack_table = NULL; + } + return 0; +} +early_param("stack_depot_disable", is_stack_depot_disabled); + +int __init stack_depot_init(void) +{ + if (!stack_depot_disable) { + size_t size = (STACK_HASH_SIZE * sizeof(struct stack_record *)); + int i; + + stack_table = memblock_alloc(size, size); + for (i = 0; i < STACK_HASH_SIZE; i++) + stack_table[i] = NULL; + } + return 0; +} /* Calculate hash for a stack */ static inline u32 hash_stack(unsigned long *entries, unsigned int size) @@ -241,7 +265,7 @@ depot_stack_handle_t stack_depot_save(un unsigned long flags; u32 hash; - if (unlikely(nr_entries == 0)) + if (unlikely(nr_entries == 0) || stack_depot_disable) goto fast_exit; hash = hash_stack(entries, nr_entries); _
