On Fri, May 18, 2012 at 02:58:51PM -0400, Dave Jones wrote: > On Thu, May 17, 2012 at 05:31:20PM -0400, Dave Jones wrote: > > > ============================================================================= > > BUG numa_policy (Not tainted): Poison overwritten > > ----------------------------------------------------------------------------- > > > > INFO: 0xffff880146498250-0xffff880146498250. First byte 0x6a instead of 0x6b > > INFO: Allocated in mpol_new+0xa3/0x140 age=46310 cpu=6 pid=32154 > > __slab_alloc+0x3d3/0x445 > > kmem_cache_alloc+0x29d/0x2b0 > > mpol_new+0xa3/0x140 > > sys_mbind+0x142/0x620 > > system_call_fastpath+0x16/0x1b > > INFO: Freed in __mpol_put+0x27/0x30 age=46268 cpu=6 pid=32154 > > __slab_free+0x2e/0x1de > > kmem_cache_free+0x25a/0x260 > > __mpol_put+0x27/0x30 > > remove_vma+0x68/0x90 > > exit_mmap+0x118/0x140 > > mmput+0x73/0x110 > > exit_mm+0x108/0x130 > > do_exit+0x162/0xb90 > > do_group_exit+0x4f/0xc0 > > sys_exit_group+0x17/0x20 > > system_call_fastpath+0x16/0x1b > > INFO: Slab 0xffffea0005192600 objects=27 used=27 fp=0x (null) flags=0x20000000004080 > > INFO: Object 0xffff880146498250 @offset=592 fp=0xffff88014649b9d0 > > As I can reproduce this fairly easily, I enabled the dynamic debug prints for mempolicy.c, > and noticed something odd (but different to the above trace..) > > INFO: 0xffff88014649abf0-0xffff88014649abf0. First byte 0x6a instead of 0x6b > INFO: Allocated in mpol_new+0xa3/0x140 age=196087 cpu=7 pid=11496 > __slab_alloc+0x3d3/0x445 > kmem_cache_alloc+0x29d/0x2b0 > mpol_new+0xa3/0x140 > sys_mbind+0x142/0x620 > system_call_fastpath+0x16/0x1b > INFO: Freed in __mpol_put+0x27/0x30 age=40838 cpu=7 pid=20824 > __slab_free+0x2e/0x1de > kmem_cache_free+0x25a/0x260 > __mpol_put+0x27/0x30 > mpol_set_shared_policy+0xe6/0x280 > shmem_set_policy+0x2a/0x30 > shm_set_policy+0x28/0x30 > sys_mbind+0x4e7/0x620 > system_call_fastpath+0x16/0x1b > INFO: Slab 0xffffea0005192600 objects=27 used=27 fp=0x (null) flags=0x20000000004080 > INFO: Object 0xffff88014649abf0 @offset=11248 fp=0xffff880146498de0 > > In this case, it seems the policy was allocated by pid 11496, and freed by a different pid! > How is that possible ? (Does kind of explain why it looks like a double-free though I guess). > > debug printout for the relevant pids below, in case it yields further clues.. Anyone ? This can be reproduced very quickly by doing.. $ git clone git://git.codemonkey.org.uk/trinity.git $ make $ ./trinity -q -c mbind On my 8-core box, it happens within 30 seconds. If I run this long enough, the box wedges completely, needing a power cycle to reboot. Dave -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>