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authorChintan Pandya <cpandya@codeaurora.org>2018-04-06 01:20:15 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-06 06:36:23 +0200
commit86609d3319ad57ff65c20890391a035acad47bb1 (patch)
tree812a45def82edb6a8c4cecde8e1cd32f8174bc00 /mm/slub.c
parentmm/slab_common.c: mark kmalloc machinery as __ro_after_init (diff)
downloadlinux-86609d3319ad57ff65c20890391a035acad47bb1.tar.xz
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mm/slub.c: use jitter-free reference while printing age
When SLUB_DEBUG catches some issues, it prints all the required debug info. However, in a few cases where allocation and free of the object has happened in a very short time, 'age' might be misleading. See the example below: ============================================================================= BUG kmalloc-256 (Tainted: G W O ): Poison overwritten ----------------------------------------------------------------------------- ... INFO: Allocated in binder_transaction+0x4b0/0x2448 age=731 cpu=3 pid=5314 ... INFO: Freed in binder_free_transaction+0x2c/0x58 age=735 cpu=6 pid=2079 ... Object fffffff14956a870: 6b 6b 6b 6b 6b 6b 6b 6b 67 6b 6b 6b 6b 6b 6b a5 kkkkkkkkgkkkk In this case, object got freed later but 'age' shows otherwise. This could be because, while printing this info, we print allocation traces first and free traces thereafter. In between, if we get schedule out or jiffies increment, (jiffies - t->when) could become meaningless. Use the jitter free reference to calculate age. New output will exactly be same. 'age' is still staying with single jiffies ref in both prints. Change-Id: I0846565807a4229748649bbecb1ffb743d71fcd8 Link: http://lkml.kernel.org/r/1520492010-19389-1-git-send-email-cpandya@codeaurora.org Signed-off-by: Chintan Pandya <cpandya@codeaurora.org> Acked-by: Christoph Lameter <cl@linux.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> 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>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/mm/slub.c b/mm/slub.c
index e381728a3751..d92218ed7f1c 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -598,13 +598,13 @@ static void init_tracking(struct kmem_cache *s, void *object)
set_track(s, object, TRACK_ALLOC, 0UL);
}
-static void print_track(const char *s, struct track *t)
+static void print_track(const char *s, struct track *t, unsigned long pr_time)
{
if (!t->addr)
return;
pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
- s, (void *)t->addr, jiffies - t->when, t->cpu, t->pid);
+ s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
#ifdef CONFIG_STACKTRACE
{
int i;
@@ -619,11 +619,12 @@ static void print_track(const char *s, struct track *t)
static void print_tracking(struct kmem_cache *s, void *object)
{
+ unsigned long pr_time = jiffies;
if (!(s->flags & SLAB_STORE_USER))
return;
- print_track("Allocated", get_track(s, object, TRACK_ALLOC));
- print_track("Freed", get_track(s, object, TRACK_FREE));
+ print_track("Allocated", get_track(s, object, TRACK_ALLOC), pr_time);
+ print_track("Freed", get_track(s, object, TRACK_FREE), pr_time);
}
static void print_page_info(struct page *page)