mm, tracing: record slab name for kmem_cache_free()

Currently, a trace record generated by the RCU core is as below.

... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=00000000f3b49a66

It doesn't tell us what the RCU core has freed.

This patch adds the slab name to trace_kmem_cache_free().
The new format is as follows.

... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=0000000037f79c8d name=dentry
... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=00000000f78cb7b5 name=sock_inode_cache
... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=0000000018768985 name=pool_workqueue
... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=000000006a6cb484 name=radix_tree_node

We can use it to understand what the RCU core is going to free. For
example, some users maybe interested in when the RCU core starts
freeing reclaimable slabs like dentry to reduce memory pressure.

Link: https://lkml.kernel.org/r/20201216072804.8838-1-jian.w.wen@oracle.com
Signed-off-by: Jacob Wen <jian.w.wen@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index f65b1f6db22d868485a6cd43eb884935bda11d0f..40845b0d5dad79cd0df4427417c634749471c6e3 100644 (file)
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -115,7 +115,7 @@ DEFINE_EVENT(kmem_alloc_node, kmem_cache_alloc_node,
        TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags, node)
 );
 
-DECLARE_EVENT_CLASS(kmem_free,
+TRACE_EVENT(kfree,
 
        TP_PROTO(unsigned long call_site, const void *ptr),
 
@@ -135,18 +135,26 @@ DECLARE_EVENT_CLASS(kmem_free,
                  (void *)__entry->call_site, __entry->ptr)
 );
 
-DEFINE_EVENT(kmem_free, kfree,
+TRACE_EVENT(kmem_cache_free,
 
-       TP_PROTO(unsigned long call_site, const void *ptr),
+       TP_PROTO(unsigned long call_site, const void *ptr, const char *name),
 
-       TP_ARGS(call_site, ptr)
-);
+       TP_ARGS(call_site, ptr, name),
 
-DEFINE_EVENT(kmem_free, kmem_cache_free,
+       TP_STRUCT__entry(
+               __field(        unsigned long,  call_site       )
+               __field(        const void *,   ptr             )
+               __field(        const char *,   name            )
+       ),
 
-       TP_PROTO(unsigned long call_site, const void *ptr),
+       TP_fast_assign(
+               __entry->call_site      = call_site;
+               __entry->ptr            = ptr;
+               __entry->name           = name;
+       ),
 
-       TP_ARGS(call_site, ptr)
+       TP_printk("call_site=%pS ptr=%p name=%s",
+                 (void *)__entry->call_site, __entry->ptr, __entry->name)
 );
 
 TRACE_EVENT(mm_page_free,

diff --git a/mm/slab.c b/mm/slab.c
index dcc55e78f3534a97682b173ea3ed2506d1bafbfb..2ed27849d1f28c8b8b4b9b765a8f56bd139b5cde 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3717,7 +3717,7 @@ void kmem_cache_free(struct kmem_cache *cachep, void *objp)
        __cache_free(cachep, objp, _RET_IP_);
        local_irq_restore(flags);
 
-       trace_kmem_cache_free(_RET_IP_, objp);
+       trace_kmem_cache_free(_RET_IP_, objp, cachep->name);
 }
 EXPORT_SYMBOL(kmem_cache_free);
 

diff --git a/mm/slob.c b/mm/slob.c
index ef87ada8705d8d1fa5e264d74744a87c3743bb07..0578429b991b4bdeef0ad17250c4c1a3502673ed 100644 (file)
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -673,7 +673,7 @@ void kmem_cache_free(struct kmem_cache *c, void *b)
                __kmem_cache_free(b, c->size);
        }
 
-       trace_kmem_cache_free(_RET_IP_, b);
+       trace_kmem_cache_free(_RET_IP_, b, c->name);
 }
 EXPORT_SYMBOL(kmem_cache_free);
 

diff --git a/mm/slub.c b/mm/slub.c
index f5baf429654f24d6dc056f1edeab02a00f7b9f39..f4dc70228861b61ccb7d77d3248d185bf5553c16 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3157,7 +3157,7 @@ void kmem_cache_free(struct kmem_cache *s, void *x)
        if (!s)
                return;
        slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_);
-       trace_kmem_cache_free(_RET_IP_, x);
+       trace_kmem_cache_free(_RET_IP_, x, s->name);
 }
 EXPORT_SYMBOL(kmem_cache_free);