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It's weird to me that no one has complained about this bug in real life but I suppose that unless you have kfree poisoning or KASAN enabled then probably you wouldn't notice it. ] Hello Lars Ellenberg, Commit 9e276872fe16 ("drbd: allow parallel promote/demote actions") from Apr 28, 2014 (linux-next), leads to the following Smatch static checker warning: drivers/block/drbd/drbd_nl.c:4564 drbd_adm_down() error: dereferencing freed memory 'resource' (line 4562) drivers/block/drbd/drbd_nl.c:4585 drbd_adm_del_resource() error: dereferencing freed memory 'resource' (line 4584) drivers/block/drbd/drbd_nl.c 4552 /* delete volumes */ 4553 idr_for_each_entry(&resource->devices, device, i) { 4554 retcode = adm_del_minor(device); 4555 if (retcode != NO_ERROR) { 4556 /* "can not happen" */ 4557 drbd_msg_put_info(adm_ctx->reply_skb, "failed to delete volume"); 4558 goto out; 4559 } 4560 } 4561 4562 retcode = adm_del_resource(resource); ^^^^^^^^^^^^^^^^^^^^^^^^^^ This frees "resource" 4563 out: --> 4564 mutex_unlock(&resource->adm_mutex); ^^^^^^^^^ Use after free. 4565 finish: 4566 adm_ctx->reply_dh->ret_code = retcode; 4567 return 0; 4568 } This email is a free service from the Smatch-CI project [smatch.sf.net]. regards, dan carpenter