On Sat, Mar 12, 2022 at 01:53:26AM +0000, Hyeonggon Yoo wrote: > On Fri, Mar 04, 2022 at 04:06:19PM +0900, Byungchul Park wrote: > > Hi Linus and folks, > > > > I've been developing a tool for detecting deadlock possibilities by > > tracking wait/event rather than lock(?) acquisition order to try to > > cover all synchonization machanisms. It's done on v5.17-rc1 tag. > > > > https://github.com/lgebyungchulpark/linux-dept/commits/dept1.14_on_v5.17-rc1 > > > > Small feedback unrelated to thread: > I'm not sure "Need to expand the ring buffer" is something to call > WARN(). Is this stack trace useful for something? > ======== > > Hello Byungchul. These are two warnings of DEPT on system. Hi Hyeonggon, Could you run scripts/decode_stacktrace.sh and share the result instead of the raw format below if the reports still appear with PATCH v5? It'd be appreciated (: https://lkml.org/lkml/2022/3/15/1277 (or https://github.com/lgebyungchulpark/linux-dept/commits/dept1.18_on_v5.17-rc7) Thank you very much! -- Byungchul > Both cases look similar. > > In what case DEPT says (unknown)? > I'm not sure we can properly debug this. > > =================================================== > DEPT: Circular dependency has been detected. > 5.17.0-rc1+ #3 Tainted: G W > --------------------------------------------------- > summary > --------------------------------------------------- > *** AA DEADLOCK *** > > context A > [S] (unknown)(&vfork:0) > [W] wait_for_completion_killable(&vfork:0) > [E] complete(&vfork:0) > > [S]: start of the event context > [W]: the wait blocked > [E]: the event not reachable > --------------------------------------------------- > context A's detail > --------------------------------------------------- > context A > [S] (unknown)(&vfork:0) > [W] wait_for_completion_killable(&vfork:0) > [E] complete(&vfork:0) > > [S] (unknown)(&vfork:0): > (N/A) > > [W] wait_for_completion_killable(&vfork:0): > [<ffffffc00802204c>] kernel_clone+0x25c/0x2b8 > stacktrace: > dept_wait+0x74/0x88 > wait_for_completion_killable+0x60/0xa0 > kernel_clone+0x25c/0x2b8 > __do_sys_clone+0x5c/0x74 > __arm64_sys_clone+0x18/0x20 > invoke_syscall.constprop.0+0x78/0xc4 > do_el0_svc+0x98/0xd0 > el0_svc+0x44/0xe4 > el0t_64_sync_handler+0xb0/0x12c > el0t_64_sync+0x158/0x15c > > [E] complete(&vfork:0): > [<ffffffc00801f49c>] mm_release+0x7c/0x90 > stacktrace: > dept_event+0xe0/0x100 > complete+0x48/0x98 > mm_release+0x7c/0x90 > exit_mm_release+0xc/0x14 > do_exit+0x1b4/0x81c > do_group_exit+0x30/0x9c > __wake_up_parent+0x0/0x24 > invoke_syscall.constprop.0+0x78/0xc4 > do_el0_svc+0x98/0xd0 > el0_svc+0x44/0xe4 > el0t_64_sync_handler+0xb0/0x12c > el0t_64_sync+0x158/0x15c > --------------------------------------------------- > information that might be helpful > --------------------------------------------------- > CPU: 6 PID: 229 Comm: start-stop-daem Tainted: G W 5.17.0-rc1+ #3 > Hardware name: linux,dummy-virt (DT) > Call trace: > dump_backtrace.part.0+0x9c/0xc4 > show_stack+0x14/0x28 > dump_stack_lvl+0x9c/0xcc > dump_stack+0x14/0x2c > print_circle+0x2d4/0x438 > cb_check_dl+0x44/0x70 > bfs+0x60/0x168 > add_dep+0x88/0x11c > do_event.constprop.0+0x19c/0x2c0 > dept_event+0xe0/0x100 > complete+0x48/0x98 > mm_release+0x7c/0x90 > exit_mm_release+0xc/0x14 > do_exit+0x1b4/0x81c > do_group_exit+0x30/0x9c > __wake_up_parent+0x0/0x24 > invoke_syscall.constprop.0+0x78/0xc4 > do_el0_svc+0x98/0xd0 > el0_svc+0x44/0xe4 > el0t_64_sync_handler+0xb0/0x12c > el0t_64_sync+0x158/0x15c > > > > > =================================================== > DEPT: Circular dependency has been detected. > 5.17.0-rc1+ #3 Tainted: G W > --------------------------------------------------- > summary > --------------------------------------------------- > *** AA DEADLOCK *** > > context A > [S] (unknown)(&try_completion:0) > [W] wait_for_completion_timeout(&try_completion:0) > [E] complete(&try_completion:0) > > [S]: start of the event context > [W]: the wait blocked > [E]: the event not reachable > --------------------------------------------------- > context A's detail > --------------------------------------------------- > context A > [S] (unknown)(&try_completion:0) > [W] wait_for_completion_timeout(&try_completion:0) > [E] complete(&try_completion:0) > > [S] (unknown)(&try_completion:0): > (N/A) > > [W] wait_for_completion_timeout(&try_completion:0): > [<ffffffc008166bf4>] kunit_try_catch_run+0xb4/0x160 > stacktrace: > dept_wait+0x74/0x88 > wait_for_completion_timeout+0x64/0xa0 > kunit_try_catch_run+0xb4/0x160 > kunit_test_try_catch_successful_try_no_catch+0x3c/0x98 > kunit_try_run_case+0x9c/0xa0 > kunit_generic_run_threadfn_adapter+0x1c/0x28 > kthread+0xd4/0xe4 > ret_from_fork+0x10/0x20 > > [E] complete(&try_completion:0): > [<ffffffc00803dce4>] kthread_complete_and_exit+0x18/0x20 > stacktrace: > dept_event+0xe0/0x100 > complete+0x48/0x98 > kthread_complete_and_exit+0x18/0x20 > kunit_try_catch_throw+0x0/0x1c > kthread+0xd4/0xe4 > ret_from_fork+0x10/0x20 > > --------------------------------------------------- > information that might be helpful > --------------------------------------------------- > CPU: 15 PID: 132 Comm: kunit_try_catch Tainted: G W 5.17.0-rc1+ #3 > Hardware name: linux,dummy-virt (DT) > Call trace: > dump_backtrace.part.0+0x9c/0xc4 > show_stack+0x14/0x28 > dump_stack_lvl+0x9c/0xcc > dump_stack+0x14/0x2c > print_circle+0x2d4/0x438 > cb_check_dl+0x44/0x70 > bfs+0x60/0x168 > add_dep+0x88/0x11c > do_event.constprop.0+0x19c/0x2c0 > dept_event+0xe0/0x100 > complete+0x48/0x98 > kthread_complete_and_exit+0x18/0x20 > kunit_try_catch_throw+0x0/0x1c > kthread+0xd4/0xe4 > ret_from_fork+0x10/0x20 > > > > Benifit: > > > > 0. Works with all lock primitives. > > 1. Works with wait_for_completion()/complete(). > > 2. Works with 'wait' on PG_locked. > > 3. Works with 'wait' on PG_writeback. > > 4. Works with swait/wakeup. > > 5. Works with waitqueue. > > 6. Multiple reports are allowed. > > 7. Deduplication control on multiple reports. > > 8. Withstand false positives thanks to 6. > > 9. Easy to tag any wait/event. > > > > Future work: > > [...] > > > -- > > 1.9.1 > > > > -- > Thank you, You are awesome! > Hyeonggon :-)
