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Message-Id: <20210414163434.4376-1-glittao@gmail.com>
Date: Wed, 14 Apr 2021 18:34:34 +0200
From: glittao@...il.com
To: cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
iamjoonsoo.kim@....com, akpm@...ux-foundation.org, vbabka@...e.cz
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Oliver Glitta <glittao@...il.com>
Subject: [PATCH] mm/slub: use stackdepot to save stack trace in objects
From: Oliver Glitta <glittao@...il.com>
Many stack traces are similar so there are many similar arrays.
Stackdepot saves each unique stack only once.
Replace field addrs in struct track with depot_stack_handle_t handle.
Use stackdepot to save stack trace.
The benefits are smaller memory overhead and possibility to aggregate
per-cache statistics in the future using the stackdepot handle
instead of matching stacks manually.
Signed-off-by: Oliver Glitta <glittao@...il.com>
---
init/Kconfig | 1 +
mm/slub.c | 79 ++++++++++++++++++++++++++++++++--------------------
2 files changed, 50 insertions(+), 30 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index 37a17853433a..a4ed2daa6c41 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1891,6 +1891,7 @@ config SLUB_DEBUG
default y
bool "Enable SLUB debugging support" if EXPERT
depends on SLUB && SYSFS
+ select STACKDEPOT if STACKTRACE_SUPPORT
help
SLUB has extensive debug support features. Disabling these can
result in significant savings in code size. This also disables
diff --git a/mm/slub.c b/mm/slub.c
index 9c0e26ddf300..4b18499726eb 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -35,6 +35,7 @@
#include <linux/prefetch.h>
#include <linux/memcontrol.h>
#include <linux/random.h>
+#include <linux/stackdepot.h>
#include <trace/events/kmem.h>
@@ -203,8 +204,8 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
#define TRACK_ADDRS_COUNT 16
struct track {
unsigned long addr; /* Called from address */
-#ifdef CONFIG_STACKTRACE
- unsigned long addrs[TRACK_ADDRS_COUNT]; /* Called from address */
+#ifdef CONFIG_STACKDEPOT
+ depot_stack_handle_t handle;
#endif
int cpu; /* Was running on cpu */
int pid; /* Pid context */
@@ -581,22 +582,27 @@ static struct track *get_track(struct kmem_cache *s, void *object,
return kasan_reset_tag(p + alloc);
}
+#ifdef CONFIG_STACKDEPOT
+static depot_stack_handle_t save_stack_trace(gfp_t flags)
+{
+ unsigned long entries[TRACK_ADDRS_COUNT];
+ depot_stack_handle_t handle;
+ unsigned int nr_entries;
+
+ nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 4);
+ handle = stack_depot_save(entries, nr_entries, flags);
+ return handle;
+}
+#endif
+
static void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, unsigned long addr)
{
struct track *p = get_track(s, object, alloc);
if (addr) {
-#ifdef CONFIG_STACKTRACE
- unsigned int nr_entries;
-
- metadata_access_enable();
- nr_entries = stack_trace_save(kasan_reset_tag(p->addrs),
- TRACK_ADDRS_COUNT, 3);
- metadata_access_disable();
-
- if (nr_entries < TRACK_ADDRS_COUNT)
- p->addrs[nr_entries] = 0;
+#ifdef CONFIG_STACKDEPOT
+ p->handle = save_stack_trace(GFP_KERNEL);
#endif
p->addr = addr;
p->cpu = smp_processor_id();
@@ -623,14 +629,19 @@ static void print_track(const char *s, struct track *t, unsigned long pr_time)
pr_err("%s in %pS age=%lu cpu=%u pid=%d\n",
s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
-#ifdef CONFIG_STACKTRACE
+#ifdef CONFIG_STACKDEPOT
{
- int i;
- for (i = 0; i < TRACK_ADDRS_COUNT; i++)
- if (t->addrs[i])
- pr_err("\t%pS\n", (void *)t->addrs[i]);
- else
- break;
+ depot_stack_handle_t handle;
+ unsigned long *entries;
+ unsigned int nr_entries;
+
+ handle = READ_ONCE(t->handle);
+ if (!handle) {
+ pr_err("object allocation/free stack trace missing\n");
+ } else {
+ nr_entries = stack_depot_fetch(handle, &entries);
+ stack_trace_print(entries, nr_entries, 0);
+ }
}
#endif
}
@@ -4017,18 +4028,26 @@ void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
objp = fixup_red_left(s, objp);
trackp = get_track(s, objp, TRACK_ALLOC);
kpp->kp_ret = (void *)trackp->addr;
-#ifdef CONFIG_STACKTRACE
- for (i = 0; i < KS_ADDRS_COUNT && i < TRACK_ADDRS_COUNT; i++) {
- kpp->kp_stack[i] = (void *)trackp->addrs[i];
- if (!kpp->kp_stack[i])
- break;
- }
+#ifdef CONFIG_STACKDEPOT
+ {
+ depot_stack_handle_t handle;
+ unsigned long *entries;
+ unsigned int nr_entries;
- trackp = get_track(s, objp, TRACK_FREE);
- for (i = 0; i < KS_ADDRS_COUNT && i < TRACK_ADDRS_COUNT; i++) {
- kpp->kp_free_stack[i] = (void *)trackp->addrs[i];
- if (!kpp->kp_free_stack[i])
- break;
+ handle = READ_ONCE(trackp->handle);
+ if (handle) {
+ nr_entries = stack_depot_fetch(handle, &entries);
+ for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
+ kpp->kp_stack[i] = (void *)entries[i];
+ }
+
+ trackp = get_track(s, objp, TRACK_FREE);
+ handle = READ_ONCE(trackp->handle);
+ if (handle) {
+ nr_entries = stack_depot_fetch(handle, &entries);
+ for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
+ kpp->kp_free_stack[i] = (void *)entries[i];
+ }
}
#endif
#endif
--
2.31.1.272.g89b43f80a5
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