Re: [Crash-utility] A bug in 'bt' triggered by 'gdb set disassembly-flavor intel'

Hi Dave, a colleague of mine has noticed a strange thing using crash-6.1.3: if we execute 'gdb set disassembly-flavor intel' first thing after starting crash (I duplicated this using this command interactively, he has it in his ~/.crashrc), this might add a bogus frame to 'bt' output. The default behaviour (crash64 is crash-6.1.3 compiled from sources on x86_64): $ crash64 vmlinux vmcore-2013-02-13-00.53.52 crash64 6.1.3 ... crash64> bt 4131 PID: 4131 TASK: ffff88041369a040 CPU: 0 COMMAND: "jbd2/dm-14-8" #0 [ffff88041443d810] machine_kexec at ffffffff8103284b #1 [ffff88041443d870] crash_kexec at ffffffff810ba982 #2 [ffff88041443d940] oops_end at ffffffff81501b00 #3 [ffff88041443d970] no_context at ffffffff81043bfb #4 [ffff88041443d9c0] __bad_area_nosemaphore at ffffffff81043e85 #5 [ffff88041443da10] bad_area_nosemaphore at ffffffff81043f53 #6 [ffff88041443da20] __do_page_fault at ffffffff810446b1 #7 [ffff88041443db40] do_page_fault at ffffffff81503ade #8 [ffff88041443db70] page_fault at ffffffff81500e95 [exception RIP: __jbd2_journal_remove_checkpoint+201] RIP: ffffffffa0299a09 RSP: ffff88041443dc20 RFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8805e4c59bc0 RCX: 0000000000000000 RDX: ffff8807fb6a4278 RSI: ffff88041443dcec RDI: ffff8807fb6a4278 RBP: ffff88041443dc60 R8: 0000000000000001 R9: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000292 R13: ffff8805e4c59c48 R14: ffff88041443dfd8 R15: ffff8807fb6a4278 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #9 [ffff88041443dc68] journal_clean_one_cp_list at ffffffffa0299d84 [jbd2] #10 [ffff88041443dcc8] __jbd2_journal_clean_checkpoint_list at ffffffffa0299e3c [jbd2] #11 [ffff88041443dd28] jbd2_journal_commit_transaction at ffffffffa02978d1 [jbd2] #12 [ffff88041443de68] kjournald2 at ffffffffa029df78 [jbd2] #13 [ffff88041443dee8] kthread at ffffffff81091e06 #14 [ffff88041443df48] kernel_thread at ffffffff8100c14a Now exiting crash and starting it again:

crash64> gdb set disassembly-flavor intel crash64> bt 4131 PID: 4131 TASK: ffff88041369a040 CPU: 0 COMMAND: "jbd2/dm-14-8" #0 [ffff88041443d810] machine_kexec at ffffffff8103284b #1 [ffff88041443d870] crash_kexec at ffffffff810ba982 #2 [ffff88041443d940] oops_end at ffffffff81501b00 #3 [ffff88041443d970] no_context at ffffffff81043bfb #4 [ffff88041443d9c0] __bad_area_nosemaphore at ffffffff81043e85 #5 [ffff88041443da10] bad_area_nosemaphore at ffffffff81043f53 #6 [ffff88041443da20] __do_page_fault at ffffffff810446b1 #7 [ffff88041443db40] do_page_fault at ffffffff81503ade #8 [ffff88041443db70] page_fault at ffffffff81500e95 [exception RIP: __jbd2_journal_remove_checkpoint+201] RIP: ffffffffa0299a09 RSP: ffff88041443dc20 RFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8805e4c59bc0 RCX: 0000000000000000 RDX: ffff8807fb6a4278 RSI: ffff88041443dcec RDI: ffff8807fb6a4278 RBP: ffff88041443dc60 R8: 0000000000000001 R9: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000292 R13: ffff8805e4c59c48 R14: ffff88041443dfd8 R15: ffff8807fb6a4278 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #9 [ffff88041443dc28] __journal_remove_journal_head at ffffffffa029ee22 [jbd2] #10 [ffff88041443dc68] journal_clean_one_cp_list at ffffffffa0299d84 [jbd2] #11 [ffff88041443dcc8] __jbd2_journal_clean_checkpoint_list at ffffffffa0299e3c [jbd2] #12 [ffff88041443dd28] jbd2_journal_commit_transaction at ffffffffa02978d1 [jbd2] #13 [ffff88041443de68] kjournald2 at ffffffffa029df78 [jbd2] #14 [ffff88041443dee8] kthread at ffffffff81091e06 #15 [ffff88041443df48] kernel_thread at ffffffff8100c14a As you see, now we have #9 that was not present while using the default flavour. This is not a 6.1.3 regression - I tried an older binary (6.1.1) on the same vmcore and it behaves similarly. Regards, Alex