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lib: stackdepot: add support to disable stack depot

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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>
This commit is contained in:
Vijayanand Jitta
2021-02-25 17:21:27 -08:00
committed by Linus Torvalds
parent d262093656
commit e1fdc40334
4 changed files with 45 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
lib/stackdepot.c
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@@ -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);