On 9/7/24 01:34, Konstantin Khorenko wrote:
Introduce 2 ways to setup/configure "unlimited_slabs" tweak:
1. "unlimited_slabs=" kernel boot option
* "unlimited_slabs=1" to enable the tweak
* "unlimited_slabs=0" to disable the tweak
2. /sys/kernel/debug/unlimited_slabs entry
* echo 1 > /sys/kernel/debug/unlimited_slabs to enable the tweak
* echo 0 > /sys/kernel/debug/unlimited_slabs to disable the tweak
The "unlimited_slabs" functionality is disabled by default.
https://virtuozzo.atlassian.net/browse/PSBM-155867
Signed-off-by: Konstantin Khorenko <khore...@virtuozzo.com>
---
mm/slub.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 58 insertions(+), 1 deletion(-)
diff --git a/mm/slub.c b/mm/slub.c
index ea3e20e73fe6..a7d6da9b528c 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -34,6 +34,7 @@
#include <linux/stacktrace.h>
#include <linux/prefetch.h>
#include <linux/memcontrol.h>
+#include <linux/debugfs.h>
#include <trace/events/kmem.h>
@@ -2466,6 +2467,59 @@ static inline void *get_freelist(struct kmem_cache *s, struct page *page)
return freelist;
}
+struct static_key unlimited_slabs = STATIC_KEY_INIT_FALSE;
+EXPORT_SYMBOL(unlimited_slabs);
+
+#ifdef CONFIG_DEBUG_FS
+static int unlimited_slabs_get(void *data, u64 *val)
+{
+ *val = static_key_false(&unlimited_slabs);
+ return 0;
+}
+
+static int unlimited_slabs_set(void *data, u64 val)
+{
+ if (val != 0 && val != 1)
+ return -EINVAL;
+
+ if (static_key_false(&unlimited_slabs) && !val) {
+ static_key_slow_dec(&unlimited_slabs);
+ printk("unlimited_slabs tweak has been disabled\n");
+ } else if (!static_key_false(&unlimited_slabs) && val) {
+ static_key_slow_inc(&unlimited_slabs);
+ printk("unlimited_slabs tweak has been enabled\n");
+ }
+
+ return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(unlimited_slabs_fops,
+ unlimited_slabs_get, unlimited_slabs_set, "%llu\n");
+
+bool setup_unlimited_slabs_cmd;
Maybe rename from setup_unlimited_slabs_cmd to unlimited_slabs_default?
+static int __init unlimited_slabs_debugfs(void)
+{
+ void *ret;
+
+ ret = debugfs_create_file("unlimited_slabs", 0644, NULL, NULL,
+ &unlimited_slabs_fops);
+ if (!ret)
+ pr_warn("Failed to create unlimited_slabs in debugfs");
+ if (setup_unlimited_slabs_cmd) {
+ static_key_slow_inc(&unlimited_slabs);
+ printk("unlimited_slabs tweak has been enabled "
+ "due to unlimited_slabs=1 kernel boot option\n");
+ }
+ return 0;
+}
+late_initcall(unlimited_slabs_debugfs);
+
+static int __init setup_unlimited_slabs(char *str)
+{
+ return (kstrtobool(str, &setup_unlimited_slabs_cmd) == 0);
+}
+__setup("unlimited_slabs=", setup_unlimited_slabs);
Maybe we can use typesafe module_param here? Note: that noaliencache and
slab_max_order in this file use __setup instead of module_param likely
only because they do non linear conversion of arguments.
static bool __read_mostly unlimited_slabs_default = false;
module_param(unlimited_slabs_default, bool, 0);
+#endif
+
/*
* Slow path. The lockless freelist is empty or we need to perform
* debugging duties.
@@ -2619,7 +2673,10 @@ static void *___slab_alloc_unlimited(struct kmem_cache
*s, gfp_t gfpflags, int n
static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
unsigned long addr, struct kmem_cache_cpu *c)
{
- return ___slab_alloc_unlimited(s, gfpflags, node, addr, c);
+ if (static_key_false(&unlimited_slabs))
+ return ___slab_alloc_unlimited(s, gfpflags, node, addr, c);
+ else
+ return ___slab_alloc_limited(s, gfpflags, node, addr, c);
}
/*
--
Best regards, Tikhomirov Pavel
Senior Software Developer, Virtuozzo.
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