Created attachment 51891 [details]
Example program with reachable blocks

Version:           3.6 SVN
OS:                Linux

Please see the attached example (example.c). When running valgrind on it I get:

$ valgrind --tool=memcheck --trace-children=yes --num-callers=32 --memcheck:leak-check=yes --memcheck:leak-resolution=high ./test

[skip]

==9787== 10 bytes in 1 blocks are possibly lost in loss record 5 of 12
==9787==    at 0x4C278FC: calloc (vg_replace_malloc.c:467)
==9787==    by 0x400591: init_ts1 (example.c:22)
==9787==    by 0x4005E9: main (example.c:32)
==9787== 
==9787== 10 bytes in 1 blocks are possibly lost in loss record 6 of 12
==9787==    at 0x4C278FC: calloc (vg_replace_malloc.c:467)
==9787==    by 0x4005AA: init_ts1 (example.c:23)
==9787==    by 0x4005E9: main (example.c:32)
==9787== 
==9787== 10 bytes in 1 blocks are possibly lost in loss record 7 of 12
==9787==    at 0x4C278FC: calloc (vg_replace_malloc.c:467)
==9787==    by 0x400591: init_ts1 (example.c:22)
==9787==    by 0x400601: main (example.c:33)
==9787== 
==9787== 10 bytes in 1 blocks are possibly lost in loss record 8 of 12
==9787==    at 0x4C278FC: calloc (vg_replace_malloc.c:467)
==9787==    by 0x4005AA: init_ts1 (example.c:23)
==9787==    by 0x400601: main (example.c:33)
==9787== 
==9787== 32 bytes in 1 blocks are possibly lost in loss record 12 of 12
==9787==    at 0x4C278FC: calloc (vg_replace_malloc.c:467)
==9787==    by 0x40057E: init_ts1 (example.c:21)
==9787==    by 0x400601: main (example.c:33)
==9787== 
==9787== LEAK SUMMARY:
==9787==    definitely lost: 0 bytes in 0 blocks
==9787==    indirectly lost: 0 bytes in 0 blocks
==9787==      possibly lost: 72 bytes in 5 blocks
==9787==    still reachable: 136 bytes in 7 blocks
==9787==         suppressed: 0 bytes in 0 blocks

Now please apply patch to example.c:

--- example-old.c       2010-09-23 09:24:45.000000000 +0400
+++ example.c   2010-09-23 09:24:02.000000000 +0400
@@ -7,7 +7,7 @@
     void *ptr2;
 };
 
-static struct ts1 *s1, *s2;
+static struct ts1 *s2, *s1;
 
 struct ts2 {
     struct ts1 *ts;

Possibly leaks have gone!

==9861== LEAK SUMMARY:
==9861==    definitely lost: 0 bytes in 0 blocks
==9861==    indirectly lost: 0 bytes in 0 blocks
==9861==      possibly lost: 0 bytes in 0 blocks
==9861==    still reachable: 208 bytes in 12 blocks
==9861==         suppressed: 0 bytes in 0 blocks


Reproducible: Always




I've added debug logging to mc_leakcheck.c (please see mc_leakcheck_c_debug.patch attached).

After that I believe that there is a bug in lc_push_without_clique_if_a_chunk_ptr(): we  to re-check sub-nodes of nodes which changed its state from Possible to Reachable (please see mc_leakcheck_c_possibly_lost.patch).