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>

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 d7c8da9319c782f5dd4f20179e65c696526dc854..f35d395794bdf5743127c20ef722020c7021a090 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3697,7 +3697,7 @@ 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 8d4bfa46247f47e4d8e870f0d11c9e4d99bb88ad..ffb34600b48c365daebc3b2d94431ebe91e53f06 100644 (file)
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -667,7 +667,7 @@ 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 d9e4e10683cc129c33c67864e75c926a5a7bf9d6..f695b07fee48e91f1c80903fde21ca3b70466137 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3156,7 +3156,7 @@ 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);