https://bugzilla.kernel.org/show_bug.cgi?id=219166 --- Comment #13 from Richard W.M. Jones (rjones@xxxxxxxxxx) --- To document for myself and others what I did to reproduce the bug and get the kernel stack trace ... (1) libguestfs from git with this patch reverted: https://github.com/libguestfs/libguestfs/commit/b2d682a4730ead8b4ae07e5aaf6fa230c5eec305 (2) Run guestfish in a loop until it hangs: $ while LIBGUESTFS_BACKEND_SETTINGS=force_tcg ./run guestfish -a /dev/null run -vx >& /tmp/log ; do echo -n . ; done (3) Looking /tmp/log we can see it hung just after trying to set noop scheduler: $ tail -5 /tmp/log + echo 300 + for f in /sys/block/sd*/device/timeout + echo 300 + for f in /sys/block/{h,s,ub,v}d*/queue/scheduler + echo noop (4) Check the log for the kernel version, install the corresponding kernel debuginfo. (5) Get virsh to produce a core dump of the VM: $ virsh list Id Name State -------------------------------------------- 1950 guestfs-lsdbxy71u4jg1w6x running $ virsh dump 1950 /var/tmp/core --memory-only Domain '1950' dumped to /var/tmp/core (6) Open in 'crash': $ crash /usr/lib/debug/lib/modules/6.11.0-0.rc5.20240830git20371ba12063.47.fc42.x86_64/vmlinux /var/tmp/core (7) List processes and find the one which hung: crash> ps ... 230 73 0 ffffa01f83c58000 UN 0.3 11608 3340 modprobe (8) Get stack trace from the hung process: crash> set 230 PID: 230 COMMAND: "modprobe" TASK: ffffa01f83c58000 [THREAD_INFO: ffffa01f83c58000] CPU: 0 STATE: TASK_UNINTERRUPTIBLE crash> bt PID: 230 TASK: ffffa01f83c58000 CPU: 0 COMMAND: "modprobe" #0 [ffffc1db0030f840] __schedule at ffffffff921906d0 #1 [ffffc1db0030f8f8] schedule at ffffffff92191a27 #2 [ffffc1db0030f908] __bio_queue_enter at ffffffff917e17dc #3 [ffffc1db0030f968] blk_mq_submit_bio at ffffffff917f3b4c #4 [ffffc1db0030f9f0] __submit_bio at ffffffff917e23fc #5 [ffffc1db0030fa58] submit_bio_noacct_nocheck at ffffffff917e28e6 #6 [ffffc1db0030fac0] ext4_mpage_readpages at ffffffff915cef7c #7 [ffffc1db0030fbe0] read_pages at ffffffff91381cda #8 [ffffc1db0030fc40] page_cache_ra_unbounded at ffffffff91381fb5 #9 [ffffc1db0030fca8] filemap_fault at ffffffff91376175 #10 [ffffc1db0030fd48] __do_fault at ffffffff913d1755 #11 [ffffc1db0030fd70] do_fault at ffffffff913d22e5 #12 [ffffc1db0030fda0] __handle_mm_fault at ffffffff913d8b2b #13 [ffffc1db0030fe88] handle_mm_fault at ffffffff913d9472 #14 [ffffc1db0030fec8] do_user_addr_fault at ffffffff910b34ea #15 [ffffc1db0030ff28] exc_page_fault at ffffffff92187e4e #16 [ffffc1db0030ff50] asm_exc_page_fault at ffffffff922012a6 RIP: 000055bb085508d8 RSP: 00007ffc3e731900 RFLAGS: 00010206 RAX: 00000000000becd6 RBX: 00007f39925d1cd6 RCX: 000055bb0856592a RDX: 00007ffc3e733c70 RSI: 00000000200becd6 RDI: 000055bb1a712970 RBP: 00007ffc3e731b60 R8: 0000000000000000 R9: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00000000200becd6 R13: 000055bb1a712970 R14: 00007ffc3e733c70 R15: 000055bb0856a708 ORIG_RAX: ffffffffffffffff CS: 0033 SS: 002b -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
