Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Mon, 5 Jul 2021 18:29:27 +0200 | Subject | Re: [PATCH v2] PM: domains: Shrink locking area of the gpd_list_lock |
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On Tue, Jun 29, 2021 at 12:41 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > On Thu, 24 Jun 2021 at 22:18, Stephen Boyd <swboyd@chromium.org> wrote: > > > > On trogdor devices I see the following lockdep splat when stopping > > youtube with lockdep enabled in the kernel. > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 5.13.0-rc2 #71 Not tainted > > ------------------------------------------------------ > > ThreadPoolSingl/3969 is trying to acquire lock: > > ffffff80d4d5c080 (&inst->lock#3){+.+.}-{3:3}, at: vdec_buf_cleanup+0x3c/0x17c [venus_dec] > > > > but task is already holding lock: > > ffffff80d3c3c4f8 (&q->mmap_lock){+.+.}-{3:3}, at: vb2_core_reqbufs+0xe4/0x390 [videobuf2_common] > > > > which lock already depends on the new lock. > > > > the existing dependency chain (in reverse order) is: > > > > -> #5 (&q->mmap_lock){+.+.}-{3:3}: > > __mutex_lock_common+0xcc/0xb88 > > mutex_lock_nested+0x5c/0x68 > > vb2_mmap+0xf4/0x290 [videobuf2_common] > > v4l2_m2m_fop_mmap+0x44/0x50 [v4l2_mem2mem] > > v4l2_mmap+0x5c/0xa4 > > mmap_region+0x310/0x5a4 > > do_mmap+0x348/0x43c > > vm_mmap_pgoff+0xfc/0x178 > > ksys_mmap_pgoff+0x84/0xfc > > __arm64_compat_sys_aarch32_mmap2+0x2c/0x38 > > invoke_syscall+0x54/0x110 > > el0_svc_common+0x88/0xf0 > > do_el0_svc_compat+0x28/0x34 > > el0_svc_compat+0x24/0x34 > > el0_sync_compat_handler+0xc0/0xf0 > > el0_sync_compat+0x19c/0x1c0 > > > > -> #4 (&mm->mmap_lock){++++}-{3:3}: > > __might_fault+0x60/0x88 > > filldir64+0x124/0x3a0 > > dcache_readdir+0x7c/0x1ec > > iterate_dir+0xc4/0x184 > > __arm64_sys_getdents64+0x78/0x170 > > invoke_syscall+0x54/0x110 > > el0_svc_common+0xa8/0xf0 > > do_el0_svc_compat+0x28/0x34 > > el0_svc_compat+0x24/0x34 > > el0_sync_compat_handler+0xc0/0xf0 > > el0_sync_compat+0x19c/0x1c0 > > > > -> #3 (&sb->s_type->i_mutex_key#3){++++}-{3:3}: > > down_write+0x94/0x1f4 > > start_creating+0xb0/0x174 > > debugfs_create_dir+0x28/0x138 > > opp_debug_register+0x88/0xc0 > > _add_opp_dev+0x84/0x9c > > _add_opp_table_indexed+0x16c/0x310 > > _of_add_table_indexed+0x70/0xb5c > > dev_pm_opp_of_add_table_indexed+0x20/0x2c > > of_genpd_add_provider_onecell+0xc4/0x1c8 > > rpmhpd_probe+0x21c/0x278 > > platform_probe+0xb4/0xd4 > > really_probe+0x140/0x35c > > driver_probe_device+0x90/0xcc > > __device_attach_driver+0xa4/0xc0 > > bus_for_each_drv+0x8c/0xd8 > > __device_attach+0xc4/0x150 > > device_initial_probe+0x20/0x2c > > bus_probe_device+0x40/0xa4 > > device_add+0x22c/0x3fc > > of_device_add+0x44/0x54 > > of_platform_device_create_pdata+0xb0/0xf4 > > of_platform_bus_create+0x1d0/0x350 > > of_platform_populate+0x80/0xd4 > > devm_of_platform_populate+0x64/0xb0 > > rpmh_rsc_probe+0x378/0x3dc > > platform_probe+0xb4/0xd4 > > really_probe+0x140/0x35c > > driver_probe_device+0x90/0xcc > > __device_attach_driver+0xa4/0xc0 > > bus_for_each_drv+0x8c/0xd8 > > __device_attach+0xc4/0x150 > > device_initial_probe+0x20/0x2c > > bus_probe_device+0x40/0xa4 > > device_add+0x22c/0x3fc > > of_device_add+0x44/0x54 > > of_platform_device_create_pdata+0xb0/0xf4 > > of_platform_bus_create+0x1d0/0x350 > > of_platform_bus_create+0x21c/0x350 > > of_platform_populate+0x80/0xd4 > > of_platform_default_populate_init+0xb8/0xd4 > > do_one_initcall+0x1b4/0x400 > > do_initcall_level+0xa8/0xc8 > > do_initcalls+0x5c/0x9c > > do_basic_setup+0x2c/0x38 > > kernel_init_freeable+0x1a4/0x1ec > > kernel_init+0x20/0x118 > > ret_from_fork+0x10/0x30 > > > > -> #2 (gpd_list_lock){+.+.}-{3:3}: > > __mutex_lock_common+0xcc/0xb88 > > mutex_lock_nested+0x5c/0x68 > > __genpd_dev_pm_attach+0x70/0x18c > > genpd_dev_pm_attach_by_id+0xe4/0x158 > > genpd_dev_pm_attach_by_name+0x48/0x60 > > dev_pm_domain_attach_by_name+0x2c/0x38 > > dev_pm_opp_attach_genpd+0xac/0x160 > > vcodec_domains_get+0x94/0x14c [venus_core] > > core_get_v4+0x150/0x188 [venus_core] > > venus_probe+0x138/0x444 [venus_core] > > platform_probe+0xb4/0xd4 > > really_probe+0x140/0x35c > > driver_probe_device+0x90/0xcc > > device_driver_attach+0x58/0x7c > > __driver_attach+0xc8/0xe0 > > bus_for_each_dev+0x88/0xd4 > > driver_attach+0x30/0x3c > > bus_add_driver+0x10c/0x1e0 > > driver_register+0x70/0x108 > > __platform_driver_register+0x30/0x3c > > 0xffffffde113e1044 > > do_one_initcall+0x1b4/0x400 > > do_init_module+0x64/0x1fc > > load_module+0x17f4/0x1958 > > __arm64_sys_finit_module+0xb4/0xf0 > > invoke_syscall+0x54/0x110 > > el0_svc_common+0x88/0xf0 > > do_el0_svc_compat+0x28/0x34 > > el0_svc_compat+0x24/0x34 > > el0_sync_compat_handler+0xc0/0xf0 > > el0_sync_compat+0x19c/0x1c0 > > > > -> #1 (&opp_table->genpd_virt_dev_lock){+.+.}-{3:3}: > > __mutex_lock_common+0xcc/0xb88 > > mutex_lock_nested+0x5c/0x68 > > _set_required_opps+0x74/0x120 > > _set_opp+0x94/0x37c > > dev_pm_opp_set_rate+0xa0/0x194 > > core_clks_set_rate+0x28/0x58 [venus_core] > > load_scale_v4+0x228/0x2b4 [venus_core] > > session_process_buf+0x160/0x198 [venus_core] > > venus_helper_vb2_buf_queue+0xcc/0x130 [venus_core] > > vdec_vb2_buf_queue+0xc4/0x140 [venus_dec] > > __enqueue_in_driver+0x164/0x188 [videobuf2_common] > > vb2_core_qbuf+0x13c/0x47c [videobuf2_common] > > vb2_qbuf+0x88/0xec [videobuf2_v4l2] > > v4l2_m2m_qbuf+0x84/0x15c [v4l2_mem2mem] > > v4l2_m2m_ioctl_qbuf+0x24/0x30 [v4l2_mem2mem] > > v4l_qbuf+0x54/0x68 > > __video_do_ioctl+0x2bc/0x3bc > > video_usercopy+0x558/0xb04 > > video_ioctl2+0x24/0x30 > > v4l2_ioctl+0x58/0x68 > > v4l2_compat_ioctl32+0x84/0xa0 > > __arm64_compat_sys_ioctl+0x12c/0x140 > > invoke_syscall+0x54/0x110 > > el0_svc_common+0x88/0xf0 > > do_el0_svc_compat+0x28/0x34 > > el0_svc_compat+0x24/0x34 > > el0_sync_compat_handler+0xc0/0xf0 > > el0_sync_compat+0x19c/0x1c0 > > > > -> #0 (&inst->lock#3){+.+.}-{3:3}: > > __lock_acquire+0x248c/0x2d6c > > lock_acquire+0x240/0x314 > > __mutex_lock_common+0xcc/0xb88 > > mutex_lock_nested+0x5c/0x68 > > vdec_buf_cleanup+0x3c/0x17c [venus_dec] > > __vb2_queue_free+0x98/0x204 [videobuf2_common] > > vb2_core_reqbufs+0x14c/0x390 [videobuf2_common] > > vb2_reqbufs+0x58/0x74 [videobuf2_v4l2] > > v4l2_m2m_reqbufs+0x58/0x90 [v4l2_mem2mem] > > v4l2_m2m_ioctl_reqbufs+0x24/0x30 [v4l2_mem2mem] > > v4l_reqbufs+0x58/0x6c > > __video_do_ioctl+0x2bc/0x3bc > > video_usercopy+0x558/0xb04 > > video_ioctl2+0x24/0x30 > > v4l2_ioctl+0x58/0x68 > > v4l2_compat_ioctl32+0x84/0xa0 > > __arm64_compat_sys_ioctl+0x12c/0x140 > > invoke_syscall+0x54/0x110 > > el0_svc_common+0x88/0xf0 > > do_el0_svc_compat+0x28/0x34 > > el0_svc_compat+0x24/0x34 > > el0_sync_compat_handler+0xc0/0xf0 > > el0_sync_compat+0x19c/0x1c0 > > > > other info that might help us debug this: > > > > Chain exists of: > > &inst->lock#3 --> &mm->mmap_lock --> &q->mmap_lock > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(&q->mmap_lock); > > lock(&mm->mmap_lock); > > lock(&q->mmap_lock); > > lock(&inst->lock#3); > > > > *** DEADLOCK *** > > > > 1 lock held by ThreadPoolSingl/3969: > > #0: ffffff80d3c3c4f8 (&q->mmap_lock){+.+.}-{3:3}, at: vb2_core_reqbufs+0xe4/0x390 [videobuf2_common] > > > > stack backtrace: > > CPU: 2 PID: 3969 Comm: ThreadPoolSingl Not tainted 5.13.0-rc2 #71 > > Hardware name: Google Lazor (rev3+) with KB Backlight (DT) > > Call trace: > > dump_backtrace+0x0/0x1b4 > > show_stack+0x24/0x30 > > dump_stack+0xe0/0x15c > > print_circular_bug+0x32c/0x388 > > check_noncircular+0x138/0x140 > > __lock_acquire+0x248c/0x2d6c > > lock_acquire+0x240/0x314 > > __mutex_lock_common+0xcc/0xb88 > > mutex_lock_nested+0x5c/0x68 > > vdec_buf_cleanup+0x3c/0x17c [venus_dec] > > __vb2_queue_free+0x98/0x204 [videobuf2_common] > > vb2_core_reqbufs+0x14c/0x390 [videobuf2_common] > > vb2_reqbufs+0x58/0x74 [videobuf2_v4l2] > > v4l2_m2m_reqbufs+0x58/0x90 [v4l2_mem2mem] > > v4l2_m2m_ioctl_reqbufs+0x24/0x30 [v4l2_mem2mem] > > v4l_reqbufs+0x58/0x6c > > __video_do_ioctl+0x2bc/0x3bc > > video_usercopy+0x558/0xb04 > > video_ioctl2+0x24/0x30 > > v4l2_ioctl+0x58/0x68 > > v4l2_compat_ioctl32+0x84/0xa0 > > __arm64_compat_sys_ioctl+0x12c/0x140 > > invoke_syscall+0x54/0x110 > > el0_svc_common+0x88/0xf0 > > do_el0_svc_compat+0x28/0x34 > > el0_svc_compat+0x24/0x34 > > el0_sync_compat_handler+0xc0/0xf0 > > el0_sync_compat+0x19c/0x1c0 > > > > The 'gpd_list_lock' is nominally named as such to protect the 'gpd_list' > > from concurrent access and mutation. Unfortunately, holding that mutex > > around various OPP framework calls leads to lockdep splats because now > > we're doing various operations in OPP core such as registering with > > debugfs while holding the list lock. We don't need to hold any list > > mutex while we're calling into OPP, so let's shrink the locking area of > > the 'gpd_list_lock' so that lockdep isn't triggered. This also helps > > reduce contention on this lock, which probably doesn't matter much but > > at least is nice to have. > > > > Cc: Len Brown <len.brown@intel.com> > > Cc: Pavel Machek <pavel@ucw.cz> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: <linux-pm@vger.kernel.org> > > Cc: Viresh Kumar <vireshk@kernel.org> > > Signed-off-by: Stephen Boyd <swboyd@chromium.org> > > Thanks for fixing this! > > As I said, when discussing the previous version, I am working on > additional improvements, but this should be a step in the right > direction. > > Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Applied as 5.14-rc1 material, thanks!
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