The patch titled
Subject: mm/slub: use stackdepot to save stack trace in objects
has been added to the -mm tree. Its filename is
mm-slub-use-stackdepot-to-save-stack-trace-in-objects.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-use-stackdepot-to-save-stack-trace-in-objects.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-use-stackdepot-to-save-stack-trace-in-objects.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Oliver Glitta <glittao@xxxxxxxxx>
Subject: mm/slub: use stackdepot to save stack trace in objects
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.
Link: https://lkml.kernel.org/r/20210414163434.4376-1-glittao@xxxxxxxxx
Signed-off-by: Oliver Glitta <glittao@xxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
init/Kconfig | 1
mm/slub.c | 79 ++++++++++++++++++++++++++++++-------------------
2 files changed, 50 insertions(+), 30 deletions(-)
--- a/init/Kconfig~mm-slub-use-stackdepot-to-save-stack-trace-in-objects
+++ a/init/Kconfig
@@ -1853,6 +1853,7 @@ 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
--- a/mm/slub.c~mm-slub-use-stackdepot-to-save-stack-trace-in-objects
+++ a/mm/slub.c
@@ -25,6 +25,7 @@
#include <linux/cpuset.h>
#include <linux/mempolicy.h>
#include <linux/ctype.h>
+#include <linux/stackdepot.h>
#include <linux/debugobjects.h>
#include <linux/kallsyms.h>
#include <linux/kfence.h>
@@ -204,8 +205,8 @@ static inline bool kmem_cache_has_cpu_pa
#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 */
@@ -602,22 +603,27 @@ static struct track *get_track(struct km
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();
@@ -644,14 +650,19 @@ static void print_track(const char *s, s
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
}
@@ -4027,18 +4038,26 @@ void kmem_obj_info(struct kmem_obj_info
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
_
Patches currently in -mm which might be from glittao@xxxxxxxxx are
mm-slub-kunit-add-a-kunit-test-for-slub-debugging-functionality.patch
mm-slub-kunit-add-a-kunit-test-for-slub-debugging-functionality-fix.patch
slub-remove-resiliency_test-function.patch
mm-slub-use-stackdepot-to-save-stack-trace-in-objects.patch
