Messages in this thread | | | Subject | [GIT BISECT] BUG kmalloc-8192: Object already free from kmem_cache_destroy | From | Eric Paris <> | Date | Sun, 13 Sep 2009 14:33:55 -0400 |
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2a38a002fbee06556489091c30b04746222167e4 is first bad commit commit 2a38a002fbee06556489091c30b04746222167e4 Author: Xiaotian Feng <dfeng@redhat.com> Date: Wed Jul 22 17:03:57 2009 +0800
slub: sysfs_slab_remove should free kmem_cache when debug is enabled
kmem_cache_destroy use sysfs_slab_remove to release the kmem_cache, but when CONFIG_SLUB_DEBUG is enabled, sysfs_slab_remove just release related kobject, the whole kmem_cache is missed to release and cause a memory leak.
Acked-by: Christoph Lameer <cl@linux-foundation.org> Signed-off-by: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
CONFIG_SLUB_DEBUG=y CONFIG_SLUB=y CONFIG_SLUB_DEBUG_ON=y # CONFIG_SLUB_STATS is not set
I created a very simple kernel module which consisted only of:
static int __init kmem_cache_test_init_module(void) { struct kmem_cache *test_cachep;
test_cachep = kmem_cache_create("test_cachep", 32, 0, 0, NULL); if (test_cachep) kmem_cache_destroy(test_cachep);
return 0; }
Before this patch it works just fine. After this patch I get a bug like this:
[ 59.921431] kmem_cache_test_init_module: [ 59.922415] ============================================================================= [ 59.922418] BUG kmalloc-8192: Object already free [ 59.922419] ----------------------------------------------------------------------------- [ 59.922420] [ 59.922453] INFO: Allocated in kmem_cache_create+0x70/0x320 age=1 cpu=3 pid=1781 [ 59.922458] INFO: Freed in kmem_cache_release+0x23/0x40 age=0 cpu=3 pid=1781 [ 59.922461] INFO: Slab 0xffffea0000373cc0 objects=3 used=1 fp=0xffff8800087fa048 flags=0x200000000040c3 [ 59.922463] INFO: Object 0xffff8800087fa048 @offset=8264 fp=0xffff8800087fc090 [ 59.922463] [ 59.922465] Bytes b4 0xffff8800087fa038: 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ [ 59.922477] Object 0xffff8800087fa048: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk [ 59.922487] Object 0xffff8800087fa058: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk [snip] [ 59.923261] Object 0xffff8800087fb028: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk [ 59.923261] Object 0xffff8800087fb038: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk [ 59.923261] Redzone 0xffff8800087fc048: bb bb bb bb bb bb bb bb »»»»»»»» [ 59.923261] Padding 0xffff8800087fc088: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ [ 59.923261] Pid: 1781, comm: insmod Not tainted 2.6.31-rc2 #33 [ 59.923261] Call Trace: [ 59.923261] [<ffffffff81142e1b>] print_trailer+0xfb/0x160 [ 59.923261] [<ffffffff81142ec9>] object_err+0x49/0x70 [ 59.923261] [<ffffffff81146166>] __slab_free+0x266/0x3c0 [ 59.923261] [<ffffffff811463ac>] kfree+0xec/0x220 [ 59.923261] [<ffffffff81146c4e>] ? kmem_cache_destroy+0x20e/0x230 [ 59.923261] [<ffffffffa02d1000>] ? kmem_cache_test_init_module+0x0/0x67 [cache_test] [ 59.923261] [<ffffffffa02d1000>] ? kmem_cache_test_init_module+0x0/0x67 [cache_test] [ 59.923261] [<ffffffff81146c4e>] kmem_cache_destroy+0x20e/0x230 [ 59.923261] [<ffffffffa02d1000>] ? kmem_cache_test_init_module+0x0/0x67 [cache_test] [ 59.923261] [<ffffffffa02d104f>] kmem_cache_test_init_module+0x4f/0x67 [cache_test] [ 59.923261] [<ffffffff8100a07b>] do_one_initcall+0x4b/0x1a0 [ 59.923261] [<ffffffff810b5f08>] sys_init_module+0x108/0x260 [ 59.923261] [<ffffffff81014282>] system_call_fastpath+0x16/0x1b [ 59.923261] FIX kmalloc-8192: Object at 0xffff8800087fa048 not freed
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