On Wed, Mar 16, 2022 at 09:30:02AM +0000, Hyeonggon Yoo wrote: > On Wed, Mar 16, 2022 at 01:32:13PM +0900, Byungchul Park wrote: > > 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 (: > > > > Hi Byungchul. > > on dept1.18_on_v5.17-rc7, the kernel_clone() warning has gone. > There is one warning remaining on my system: > > It warns when running kunit-try-catch-test testcase. Hi Hyeonggon, I can reproduce it thanks to you. I will let you know on all works done. Thanks, Byungchul > =================================================== > DEPT: Circular dependency has been detected. > 5.17.0-rc7+ #4 Not tainted > --------------------------------------------------- > 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): > kunit_try_catch_run (lib/kunit/try-catch.c:78 (discriminator 1)) > stacktrace: > dept_wait (kernel/dependency/dept.c:2149) > wait_for_completion_timeout (kernel/sched/completion.c:119 (discriminator 4) kernel/sched/completion.c:165 (discriminator 4)) > kunit_try_catch_run (lib/kunit/try-catch.c:78 (discriminator 1)) > kunit_test_try_catch_successful_try_no_catch (lib/kunit/kunit-test.c:43) > kunit_try_run_case (lib/kunit/test.c:333 lib/kunit/test.c:374) > kunit_generic_run_threadfn_adapter (lib/kunit/try-catch.c:30) > kthread (kernel/kthread.c:379) > ret_from_fork (arch/arm64/kernel/entry.S:757) > > [E] complete(&try_completion:0): > kthread_complete_and_exit (kernel/kthread.c:327) > stacktrace: > dept_event (kernel/dependency/dept.c:2376 (discriminator 2)) > complete (kernel/sched/completion.c:33 (discriminator 4)) > kthread_complete_and_exit (kernel/kthread.c:327) > kunit_try_catch_throw (lib/kunit/try-catch.c:18) > kthread (kernel/kthread.c:379) > ret_from_fork (arch/arm64/kernel/entry.S:757) > > --------------------------------------------------- > information that might be helpful > --------------------------------------------------- > Hardware name: linux,dummy-virt (DT) > Call trace: > dump_backtrace.part.0 (arch/arm64/kernel/stacktrace.c:186) > show_stack (arch/arm64/kernel/stacktrace.c:193) > dump_stack_lvl (lib/dump_stack.c:107 (discriminator 4)) > dump_stack (lib/dump_stack.c:114) > print_circle (./arch/arm64/include/asm/atomic_ll_sc.h:112 ./arch/arm64/include/asm/atomic.h:30 ./include/linux/atomic/atomic-arch-fallback.h:511 ./include/linux/atomic/atomic-instrumented.h:258 kernel/dependency/dept.c:140 kernel/dependency/dept.c:748) > cb_check_dl (kernel/dependency/dept.c:1083 kernel/dependency/dept.c:1064) > bfs (kernel/dependency/dept.c:833) > add_dep (kernel/dependency/dept.c:1409) > do_event (kernel/dependency/dept.c:175 kernel/dependency/dept.c:1644) > dept_event (kernel/dependency/dept.c:2376 (discriminator 2)) > complete (kernel/sched/completion.c:33 (discriminator 4)) > kthread_complete_and_exit (kernel/kthread.c:327) > kunit_try_catch_throw (lib/kunit/try-catch.c:18) > kthread (kernel/kthread.c:379) > ret_from_fork (arch/arm64/kernel/entry.S:757) > > -- > Thank you, You are awesome! > Hyeonggon :-) > > > 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 :-)
