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Subject[PATCH] kmemtrace: trace kfree() calls with NULL or zero-length objects
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Date
From: Pekka Enberg <penberg@cs.helsinki.fi>

Impact: improve tracing

This patch moves the trace_kfree() calls before the ZERO_OR_NULL_PTR
check so that we can trace call-sites that call kfree() with NULL many
times which might be an indication of a bug.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
---
Eduard, does this require some changes in the user-space tools?

mm/slab.c | 4 ++--
mm/slob.c | 4 ++--
mm/slub.c | 4 ++--
3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index fa00fd6..b584002 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3773,6 +3773,8 @@ void kfree(const void *objp)
struct kmem_cache *c;
unsigned long flags;

+ trace_kfree(_RET_IP_, objp);
+
if (unlikely(ZERO_OR_NULL_PTR(objp)))
return;
local_irq_save(flags);
@@ -3782,8 +3784,6 @@ void kfree(const void *objp)
debug_check_no_obj_freed(objp, obj_size(c));
__cache_free(c, (void *)objp);
local_irq_restore(flags);
-
- trace_kfree(_RET_IP_, objp);
}
EXPORT_SYMBOL(kfree);

diff --git a/mm/slob.c b/mm/slob.c
index 2ccd31d..5bd7ecc 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -503,6 +503,8 @@ void kfree(const void *block)
{
struct slob_page *sp;

+ trace_kfree(_RET_IP_, block);
+
if (unlikely(ZERO_OR_NULL_PTR(block)))
return;

@@ -513,8 +515,6 @@ void kfree(const void *block)
slob_free(m, *m + align);
} else
put_page(&sp->page);
-
- trace_kfree(_RET_IP_, block);
}
EXPORT_SYMBOL(kfree);

diff --git a/mm/slub.c b/mm/slub.c
index c3a905b..988ef33 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2791,6 +2791,8 @@ void kfree(const void *x)
struct page *page;
void *object = (void *)x;

+ trace_kfree(_RET_IP_, x);
+
if (unlikely(ZERO_OR_NULL_PTR(x)))
return;

@@ -2801,8 +2803,6 @@ void kfree(const void *x)
return;
}
slab_free(page->slab, page, object, _RET_IP_);
-
- trace_kfree(_RET_IP_, x);
}
EXPORT_SYMBOL(kfree);

--
1.5.4.3




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