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>

1 files changed, 2 insertions, 0 deletions

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();