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Date: Mon, 14 Mar 2022 15:59:06 +0900 From: Byungchul Park <byungchul.park@....com> To: Hyeonggon Yoo <42.hyeyoo@...il.com> Cc: torvalds@...ux-foundation.org, damien.lemoal@...nsource.wdc.com, linux-ide@...r.kernel.org, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, mingo@...hat.com, linux-kernel@...r.kernel.org, peterz@...radead.org, will@...nel.org, tglx@...utronix.de, rostedt@...dmis.org, joel@...lfernandes.org, sashal@...nel.org, daniel.vetter@...ll.ch, chris@...is-wilson.co.uk, duyuyang@...il.com, johannes.berg@...el.com, tj@...nel.org, tytso@....edu, willy@...radead.org, david@...morbit.com, amir73il@...il.com, bfields@...ldses.org, gregkh@...uxfoundation.org, kernel-team@....com, linux-mm@...ck.org, akpm@...ux-foundation.org, mhocko@...nel.org, minchan@...nel.org, hannes@...xchg.org, vdavydov.dev@...il.com, sj@...nel.org, jglisse@...hat.com, dennis@...nel.org, cl@...ux.com, penberg@...nel.org, rientjes@...gle.com, vbabka@...e.cz, ngupta@...are.org, linux-block@...r.kernel.org, paolo.valente@...aro.org, josef@...icpanda.com, linux-fsdevel@...r.kernel.org, viro@...iv.linux.org.uk, jack@...e.cz, jack@...e.com, jlayton@...nel.org, dan.j.williams@...el.com, hch@...radead.org, djwong@...nel.org, dri-devel@...ts.freedesktop.org, airlied@...ux.ie, rodrigosiqueiramelo@...il.com, melissa.srw@...il.com, hamohammed.sa@...il.com Subject: Re: [PATCH v4 00/24] DEPT(Dependency Tracker) 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? Yeah. It seems to happen too often. I won't warn it. Thanks. > ======== > > Hello Byungchul. These are two warnings of DEPT on system. > 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) All the reports look like having to do with kernel_clone(). I need to check it more. Thank you very much. You are awesome, Hyeonggon. Thank you, Byungchul > [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 > -- > Thank you, You are awesome! > Hyeonggon :-)
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