lib: stackdepot: add support to configure STACK_HASH_SIZE

Use CONFIG_STACK_HASH_ORDER to configure STACK_HASH_SIZE.

Aim is to have configurable value for  STACK_HASH_SIZE,
so depend on use case one can configure it.

One example is of Page Owner, CONFIG_PAGE_OWNER works only if
page_owner=on via kernel parameter on CONFIG_PAGE_OWNER configured system.
Thus, unless admin enable it via command line option, the stackdepot will
just waste 8M memory without any customer.

Making it configurable and use lower value helps to enable features like
CONFIG_PAGE_OWNER without any significant overhead.

Link: https://lkml.kernel.org/r/1611749198-24316-1-git-send-email-vjitta@codeaurora.org
Signed-off-by: Yogesh Lal <ylal@codeaurora.org>
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/Kconfig b/lib/Kconfig
index 4680633..a38cc61 100644 (file)
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -651,6 +651,15 @@ config STACKDEPOT
        bool
        select STACKTRACE
 
+config STACK_HASH_ORDER
+       int "stack depot hash size (12 => 4KB, 20 => 1024KB)"
+       range 12 20
+       default 20
+       depends on STACKDEPOT
+       help
+        Select the hash size as a power of 2 for the stackdepot hash table.
+        Choose a lower value to reduce the memory impact.
+
 config SBITMAP
        bool
 

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 890dcc2..4b97154 100644 (file)
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -141,8 +141,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
        return stack;
 }
 
-#define STACK_HASH_ORDER 20
-#define STACK_HASH_SIZE (1L << STACK_HASH_ORDER)
+#define STACK_HASH_SIZE (1L << CONFIG_STACK_HASH_ORDER)
 #define STACK_HASH_MASK (STACK_HASH_SIZE - 1)
 #define STACK_HASH_SEED 0x9747b28c