[PATCH 4.9 67/94] mm/slub.c: trace free objects at KERN_INFO

Greg Kroah-Hartman
2017-06-05T16:27:15Z

From: Daniel Thompson <daniel.thompson@linaro.org>

commit aa2efd5ea4041754da4046c3d2e7edaac9526258 upstream.

Currently when trace is enabled (e.g. slub_debug=T,kmalloc-128 ) the
trace messages are mostly output at KERN_INFO. However the trace code
also calls print_section() to hexdump the head of a free object. This
is hard coded to use KERN_ERR, meaning the console is deluged with trace
messages even if we've asked for quiet.

Fix this the obvious way but adding a level parameter to
print_section(), allowing calls from the trace code to use the same
trace level as other trace messages.

Link: http://lkml.kernel.org/r/20170113154850.518-1-daniel.thompson@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
mm/slub.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

--- a/mm/slub.c
+++ b/mm/slub.c
@@ -496,10 +496,11 @@ static inline int check_valid_pointer(st
return 1;
}

-static void print_section(char *text, u8 *addr, unsigned int length)
+static void print_section(char *level, char *text, u8 *addr,
+ unsigned int length)
{
metadata_access_enable();
- print_hex_dump(KERN_ERR, text, DUMP_PREFIX_ADDRESS, 16, 1, addr,
+ print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, addr,
length, 1);
metadata_access_disable();
}
@@ -636,14 +637,15 @@ static void print_trailer(struct kmem_ca
p, p - addr, get_freepointer(s, p));

if (s->flags & SLAB_RED_ZONE)
- print_section("Redzone ", p - s->red_left_pad, s->red_left_pad);
+ print_section(KERN_ERR, "Redzone ", p - s->red_left_pad,
+ s->red_left_pad);
else if (p > addr + 16)
- print_section("Bytes b4 ", p - 16, 16);
+ print_section(KERN_ERR, "Bytes b4 ", p - 16, 16);

- print_section("Object ", p, min_t(unsigned long, s->object_size,
- PAGE_SIZE));
+ print_section(KERN_ERR, "Object ", p,
+ min_t(unsigned long, s->object_size, PAGE_SIZE));
if (s->flags & SLAB_RED_ZONE)
- print_section("Redzone ", p + s->object_size,
+ print_section(KERN_ERR, "Redzone ", p + s->object_size,
s->inuse - s->object_size);

if (s->offset)
@@ -658,7 +660,8 @@ static void print_trailer(struct kmem_ca

if (off != size_from_object(s))
/* Beginning of the filler is the free pointer */
- print_section("Padding ", p + off, size_from_object(s) - off);
+ print_section(KERN_ERR, "Padding ", p + off,
+ size_from_object(s) - off);

dump_stack();
}
@@ -820,7 +823,7 @@ static int slab_pad_check(struct kmem_ca
end--;

slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
- print_section("Padding ", end - remainder, remainder);
+ print_section(KERN_ERR, "Padding ", end - remainder, remainder);

restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end);
return 0;
@@ -973,7 +976,7 @@ static void trace(struct kmem_cache *s,
page->freelist);

if (!alloc)
- print_section("Object ", (void *)object,
+ print_section(KERN_INFO, "Object ", (void *)object,
s->object_size);

dump_stack();