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authorVijayanand Jitta <vjitta@codeaurora.org>2021-02-26 04:21:27 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-26 20:41:04 +0300
commite1fdc403349c64fa58f4c163f4bf9b860b4db808 (patch)
tree18d2e4c6908552dccc5069f3aa393e39f0ca9655
parentd262093656a0eec6d6114a3178a9d887fddd0ded (diff)
downloadlinux-e1fdc403349c64fa58f4c163f4bf9b860b4db808.tar.xz
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@linux-foundation.org: fix CONFIG_STACKDEPOT=n build] Link: https://lkml.kernel.org/r/1611749198-24316-2-git-send-email-vjitta@codeaurora.org Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org> Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org> Cc: Alexander Potapenko <glider@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Yogesh Lal <ylal@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt6
-rw-r--r--include/linux/stackdepot.h9
-rw-r--r--init/main.c2
-rw-r--r--lib/stackdepot.c32
4 files changed, 45 insertions, 4 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index bab6a8b01202..04545725f187 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/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.
diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
index 24d49c732341..6bb4bc1a5f54 100644
--- a/include/linux/stackdepot.h
+++ b/include/linux/stackdepot.h
@@ -21,4 +21,13 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
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
diff --git a/init/main.c b/init/main.c
index 261051070e3c..3648c9f94882 100644
--- a/init/main.c
+++ b/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();
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 4b9715470e87..cc21116512a7 100644
--- a/lib/stackdepot.c
+++ b/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_stack(unsigned long *entries, int size,
#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(unsigned long *entries,
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);