Re: [PATCH v12 00/25] Linux RISC-V AIA Support

[Anup Patel <apatel@ventanamicro.com>]

Hi Andrea,

On Thu, Feb 8, 2024 at 3:40 PM Andrea Parri <parri.andrea@gmail.com> wrote:
>
> Hi Anup,
>
> I understand that some refactoring is in progress, but I don't see the
> report below; adding it here hoping that it can be useful towards v13.
> (Unfortunately, I didn't have enough time to debug this yet...)
>
>
> >   irqchip/sifive-plic: Convert PLIC driver into a platform driver
>
> I'm seeing the following LOCKDEP warning with this series, bisected to
> the commit above.  This is a defconfig + PROVE_LOCKING=y build, booted
> using -machine virt,aia=none.
>
> [    0.953473] ========================================================
> [    0.953704] WARNING: possible irq lock inversion dependency detected
> [    0.953955] 6.8.0-rc1-00039-gd9b9d6eb987f #1122 Not tainted
> [    0.954224] --------------------------------------------------------
> [    0.954444] swapper/0/0 just changed the state of lock:
> [    0.954664] ffffaf808109d0c8 (&irq_desc_lock_class){-...}-{2:2}, at: handle_fasteoi_irq+0x24/0x1da
> [    0.955699] but this lock took another, HARDIRQ-unsafe lock in the past:
> [    0.955942]  (&handler->enable_lock){+.+.}-{2:2}
> [    0.955974]
>
>                and interrupts could create inverse lock ordering between them.
>
> [    0.956507]
>                other info that might help us debug this:
> [    0.956775]  Possible interrupt unsafe locking scenario:
>
> [    0.956998]        CPU0                    CPU1
> [    0.957247]        ----                    ----
> [    0.957439]   lock(&handler->enable_lock);
> [    0.957607]                                local_irq_disable();
> [    0.957793]                                lock(&irq_desc_lock_class);
> [    0.958021]                                lock(&handler->enable_lock);
> [    0.958246]   <Interrupt>
> [    0.958342]     lock(&irq_desc_lock_class);
> [    0.958501]
>                 *** DEADLOCK ***

I was able to reproduce this warning.

Further digging, it turns out the locking safety issue existed
before PLIC was converted into platform driver but was never
caught by the lock dependency because previously it was
being probed very early using IRQCHIP_DECLARE().

I will include a separate patch in v13 to fix this warning.

Thanks,
Anup



>
> [    0.958715] no locks held by swapper/0/0.
> [    0.958870]
>                the shortest dependencies between 2nd lock and 1st lock:
> [    0.959152]  -> (&handler->enable_lock){+.+.}-{2:2} {
> [    0.959372]     HARDIRQ-ON-W at:
> [    0.959522]                       __lock_acquire+0x884/0x1f5c
> [    0.959745]                       lock_acquire+0xf0/0x292
> [    0.959913]                       _raw_spin_lock+0x2c/0x40
> [    0.960090]                       plic_probe+0x322/0x65c
> [    0.960257]                       platform_probe+0x4e/0x92
> [    0.960432]                       really_probe+0x82/0x210
> [    0.960598]                       __driver_probe_device+0x5c/0xd0
> [    0.960784]                       driver_probe_device+0x2c/0xb0
> [    0.960964]                       __driver_attach+0x72/0x10a
> [    0.961151]                       bus_for_each_dev+0x60/0xac
> [    0.961330]                       driver_attach+0x1a/0x22
> [    0.961496]                       bus_add_driver+0xd4/0x19e
> [    0.961666]                       driver_register+0x3e/0xd8
> [    0.961835]                       __platform_driver_register+0x1c/0x24
> [    0.962030]                       plic_driver_init+0x1a/0x22
> [    0.962201]                       do_one_initcall+0x80/0x268
> [    0.962371]                       kernel_init_freeable+0x296/0x300
> [    0.962554]                       kernel_init+0x1e/0x10a
> [    0.962713]                       ret_from_fork+0xe/0x1c
> [    0.962884]     SOFTIRQ-ON-W at:
> [    0.962994]                       __lock_acquire+0x89e/0x1f5c
> [    0.963169]                       lock_acquire+0xf0/0x292
> [    0.963336]                       _raw_spin_lock+0x2c/0x40
> [    0.963497]                       plic_probe+0x322/0x65c
> [    0.963664]                       platform_probe+0x4e/0x92
> [    0.963849]                       really_probe+0x82/0x210
> [    0.964054]                       __driver_probe_device+0x5c/0xd0
> [    0.964255]                       driver_probe_device+0x2c/0xb0
> [    0.964428]                       __driver_attach+0x72/0x10a
> [    0.964603]                       bus_for_each_dev+0x60/0xac
> [    0.964777]                       driver_attach+0x1a/0x22
> [    0.964943]                       bus_add_driver+0xd4/0x19e
> [    0.965343]                       driver_register+0x3e/0xd8
> [    0.965527]                       __platform_driver_register+0x1c/0x24
> [    0.965732]                       plic_driver_init+0x1a/0x22
> [    0.965908]                       do_one_initcall+0x80/0x268
> [    0.966078]                       kernel_init_freeable+0x296/0x300
> [    0.966268]                       kernel_init+0x1e/0x10a
> [    0.966436]                       ret_from_fork+0xe/0x1c
> [    0.966599]     INITIAL USE at:
> [    0.966716]                      __lock_acquire+0x3fc/0x1f5c
> [    0.966891]                      lock_acquire+0xf0/0x292
> [    0.967048]                      _raw_spin_lock+0x2c/0x40
> [    0.967206]                      plic_probe+0x322/0x65c
> [    0.967360]                      platform_probe+0x4e/0x92
> [    0.967522]                      really_probe+0x82/0x210
> [    0.967678]                      __driver_probe_device+0x5c/0xd0
> [    0.967853]                      driver_probe_device+0x2c/0xb0
> [    0.968025]                      __driver_attach+0x72/0x10a
> [    0.968185]                      bus_for_each_dev+0x60/0xac
> [    0.968348]                      driver_attach+0x1a/0x22
> [    0.968513]                      bus_add_driver+0xd4/0x19e
> [    0.968678]                      driver_register+0x3e/0xd8
> [    0.968839]                      __platform_driver_register+0x1c/0x24
> [    0.969035]                      plic_driver_init+0x1a/0x22
> [    0.969239]                      do_one_initcall+0x80/0x268
> [    0.969431]                      kernel_init_freeable+0x296/0x300
> [    0.969610]                      kernel_init+0x1e/0x10a
> [    0.969766]                      ret_from_fork+0xe/0x1c
> [    0.969936]   }
> [    0.970010]   ... key      at: [<ffffffff824f4138>] __key.2+0x0/0x10
> [    0.970224]   ... acquired at:
> [    0.970353]    lock_acquire+0xf0/0x292
> [    0.970482]    _raw_spin_lock+0x2c/0x40
> [    0.970609]    plic_irq_enable+0x7e/0x140
> [    0.970739]    irq_enable+0x2c/0x60
> [    0.970882]    __irq_startup+0x58/0x60
> [    0.971008]    irq_startup+0x5e/0x13c
> [    0.971126]    __setup_irq+0x4de/0x5da
> [    0.971248]    request_threaded_irq+0xcc/0x12e
> [    0.971394]    vm_find_vqs+0x62/0x50a
> [    0.971518]    probe_common+0xfe/0x1d2
> [    0.971635]    virtrng_probe+0xc/0x14
> [    0.971751]    virtio_dev_probe+0x154/0x1fc
> [    0.971878]    really_probe+0x82/0x210
> [    0.972008]    __driver_probe_device+0x5c/0xd0
> [    0.972147]    driver_probe_device+0x2c/0xb0
> [    0.972280]    __driver_attach+0x72/0x10a
> [    0.972407]    bus_for_each_dev+0x60/0xac
> [    0.972540]    driver_attach+0x1a/0x22
> [    0.972656]    bus_add_driver+0xd4/0x19e
> [    0.972777]    driver_register+0x3e/0xd8
> [    0.972896]    register_virtio_driver+0x1c/0x2a
> [    0.973049]    virtio_rng_driver_init+0x18/0x20
> [    0.973236]    do_one_initcall+0x80/0x268
> [    0.973399]    kernel_init_freeable+0x296/0x300
> [    0.973540]    kernel_init+0x1e/0x10a
> [    0.973658]    ret_from_fork+0xe/0x1c
>
> [    0.973858] -> (&irq_desc_lock_class){-...}-{2:2} {
> [    0.974036]    IN-HARDIRQ-W at:
> [    0.974142]                     __lock_acquire+0xa82/0x1f5c
> [    0.974309]                     lock_acquire+0xf0/0x292
> [    0.974467]                     _raw_spin_lock+0x2c/0x40
> [    0.974625]                     handle_fasteoi_irq+0x24/0x1da
> [    0.974794]                     generic_handle_domain_irq+0x1c/0x2a
> [    0.974982]                     plic_handle_irq+0x7e/0xf0
> [    0.975143]                     generic_handle_domain_irq+0x1c/0x2a
> [    0.975329]                     riscv_intc_irq+0x2e/0x46
> [    0.975488]                     handle_riscv_irq+0x4a/0x74
> [    0.975652]                     call_on_irq_stack+0x32/0x40
> [    0.975817]    INITIAL USE at:
> [    0.975923]                    __lock_acquire+0x3fc/0x1f5c
> [    0.976087]                    lock_acquire+0xf0/0x292
> [    0.976244]                    _raw_spin_lock_irqsave+0x3a/0x64
> [    0.976423]                    __irq_get_desc_lock+0x5a/0x84
> [    0.976594]                    irq_modify_status+0x2a/0x106
> [    0.976764]                    irq_set_percpu_devid+0x62/0x78
> [    0.976939]                    riscv_intc_domain_map+0x1e/0x54
> [    0.977133]                    irq_domain_associate_locked+0x42/0xe4
> [    0.977363]                    irq_create_mapping_affinity+0x98/0xd4
> [    0.977570]                    sbi_ipi_init+0x70/0x142
> [    0.977744]                    init_IRQ+0xfe/0x11a
> [    0.977906]                    start_kernel+0x4ae/0x790
> [    0.978082]  }
> [    0.978151]  ... key      at: [<ffffffff824bbee0>] irq_desc_lock_class+0x0/0x10
> [    0.978389]  ... acquired at:
> [    0.978494]    mark_lock+0x3fe/0x8c2
> [    0.978624]    __lock_acquire+0xa82/0x1f5c
> [    0.978766]    lock_acquire+0xf0/0x292
> [    0.978897]    _raw_spin_lock+0x2c/0x40
> [    0.979029]    handle_fasteoi_irq+0x24/0x1da
> [    0.979171]    generic_handle_domain_irq+0x1c/0x2a
> [    0.979326]    plic_handle_irq+0x7e/0xf0
> [    0.979460]    generic_handle_domain_irq+0x1c/0x2a
> [    0.979618]    riscv_intc_irq+0x2e/0x46
> [    0.979751]    handle_riscv_irq+0x4a/0x74
> [    0.979888]    call_on_irq_stack+0x32/0x40
>
> [    0.980110]
>                stack backtrace:
> [    0.980358] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.8.0-rc1-00039-gd9b9d6eb987f #1122
> [    0.980662] Hardware name: riscv-virtio,qemu (DT)
> [    0.980913] Call Trace:
> [    0.981042] [<ffffffff80007198>] dump_backtrace+0x1c/0x24
> [    0.981246] [<ffffffff80ae020a>] show_stack+0x2c/0x38
> [    0.981456] [<ffffffff80aedac4>] dump_stack_lvl+0x5a/0x7c
> [    0.981648] [<ffffffff80aedafa>] dump_stack+0x14/0x1c
> [    0.981813] [<ffffffff80ae17a4>] print_irq_inversion_bug.part.0+0x162/0x176
> [    0.982031] [<ffffffff8007c6e6>] mark_lock+0x3fe/0x8c2
> [    0.982198] [<ffffffff8007d888>] __lock_acquire+0xa82/0x1f5c
> [    0.982377] [<ffffffff8007f59e>] lock_acquire+0xf0/0x292
> [    0.982549] [<ffffffff80af9962>] _raw_spin_lock+0x2c/0x40
> [    0.982721] [<ffffffff8008f3fe>] handle_fasteoi_irq+0x24/0x1da
> [    0.982904] [<ffffffff8008a4a4>] generic_handle_domain_irq+0x1c/0x2a
> [    0.983112] [<ffffffff80581dc0>] plic_handle_irq+0x7e/0xf0
> [    0.983293] [<ffffffff8008a4a4>] generic_handle_domain_irq+0x1c/0x2a
> [    0.983495] [<ffffffff8057fb1a>] riscv_intc_irq+0x2e/0x46
> [    0.983671] [<ffffffff80aedb4c>] handle_riscv_irq+0x4a/0x74
> [    0.983856] [<ffffffff80afa756>] call_on_irq_stack+0x32/0x40
>
>
> When I switch to -machine virt,aia=aplic-imsic (same config as above), I
> get:
>
> [    0.971406] ============================================
> [    0.971439] WARNING: possible recursive locking detected
> [    0.971497] 6.8.0-rc1-00039-gd9b9d6eb987f #1122 Not tainted
> [    0.971583] --------------------------------------------
> [    0.971612] swapper/0/1 is trying to acquire lock:
> [    0.971662] ffffaf83fefa8e78 (&lpriv->ids_lock){-...}-{2:2}, at: imsic_vector_move+0x92/0x146
> [    0.971927]
>                but task is already holding lock:
> [    0.971975] ffffaf83fef6ee78 (&lpriv->ids_lock){-...}-{2:2}, at: imsic_vector_move+0x86/0x146
> [    0.972045]
>                other info that might help us debug this:
> [    0.972085]  Possible unsafe locking scenario:
>
> [    0.972114]        CPU0
> [    0.972133]        ----
> [    0.972153]   lock(&lpriv->ids_lock);
> [    0.972191]   lock(&lpriv->ids_lock);
> [    0.972228]
>                 *** DEADLOCK ***
>
> [    0.972258]  May be due to missing lock nesting notation
>
> [    0.972306] 6 locks held by swapper/0/1:
> [    0.972338]  #0: ffffaf8081f65970 (&dev->mutex){....}-{3:3}, at: __driver_attach+0x6a/0x10a
> [    0.972413]  #1: ffffaf808217c240 (&desc->request_mutex){+.+.}-{3:3}, at: __setup_irq+0xa2/0x5da
> [    0.972492]  #2: ffffaf808217c0c8 (&irq_desc_lock_class){....}-{2:2}, at: __setup_irq+0xbe/0x5da
> [    0.972555]  #3: ffffffff81892ac0 (mask_lock){....}-{2:2}, at: irq_setup_affinity+0x38/0xc6
> [    0.972617]  #4: ffffffff81892a80 (tmp_mask_lock){....}-{2:2}, at: irq_do_set_affinity+0x3a/0x164
> [    0.972681]  #5: ffffaf83fef6ee78 (&lpriv->ids_lock){-...}-{2:2}, at: imsic_vector_move+0x86/0x146
> [    0.972753]
>                stack backtrace:
> [    0.972852] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 6.8.0-rc1-00039-gd9b9d6eb987f #1122
> [    0.972900] Hardware name: riscv-virtio,qemu (DT)
> [    0.972987] Call Trace:
> [    0.973019] [<ffffffff80007198>] dump_backtrace+0x1c/0x24
> [    0.973054] [<ffffffff80ae020a>] show_stack+0x2c/0x38
> [    0.973083] [<ffffffff80aedac4>] dump_stack_lvl+0x5a/0x7c
> [    0.973112] [<ffffffff80aedafa>] dump_stack+0x14/0x1c
> [    0.973139] [<ffffffff8007ad5e>] print_deadlock_bug+0x282/0x328
> [    0.973168] [<ffffffff8007e15c>] __lock_acquire+0x1356/0x1f5c
> [    0.973198] [<ffffffff8007f59e>] lock_acquire+0xf0/0x292
> [    0.973225] [<ffffffff80af9adc>] _raw_spin_lock_irqsave+0x3a/0x64
> [    0.973255] [<ffffffff80581210>] imsic_vector_move+0x92/0x146
> [    0.973285] [<ffffffff80581a04>] imsic_irq_set_affinity+0x8e/0xc6
> [    0.973315] [<ffffffff8008c86a>] irq_do_set_affinity+0x142/0x164
> [    0.973345] [<ffffffff8008cc22>] irq_setup_affinity+0x68/0xc6
> [    0.973374] [<ffffffff8008fa82>] irq_startup+0x72/0x13c
> [    0.973401] [<ffffffff8008d40c>] __setup_irq+0x4de/0x5da
> [    0.973430] [<ffffffff8008d5d4>] request_threaded_irq+0xcc/0x12e
> [    0.973460] [<ffffffff806346d8>] vp_find_vqs_msix+0x114/0x376
> [    0.973491] [<ffffffff80634970>] vp_find_vqs+0x36/0x136
> [    0.973518] [<ffffffff80633280>] vp_modern_find_vqs+0x16/0x4e
> [    0.973547] [<ffffffff80ab31f8>] p9_virtio_probe+0x8e/0x31c
> [    0.973576] [<ffffffff8062d982>] virtio_dev_probe+0x154/0x1fc
> [    0.973605] [<ffffffff80693738>] really_probe+0x82/0x210
> [    0.973632] [<ffffffff80693922>] __driver_probe_device+0x5c/0xd0
> [    0.973661] [<ffffffff806939c2>] driver_probe_device+0x2c/0xb0
> [    0.973690] [<ffffffff80693b46>] __driver_attach+0x72/0x10a
> [    0.973718] [<ffffffff8069191a>] bus_for_each_dev+0x60/0xac
> [    0.973746] [<ffffffff80693164>] driver_attach+0x1a/0x22
> [    0.973773] [<ffffffff80692ade>] bus_add_driver+0xd4/0x19e
> [    0.973801] [<ffffffff8069487e>] driver_register+0x3e/0xd8
> [    0.973829] [<ffffffff8062d1ce>] register_virtio_driver+0x1c/0x2a
> [    0.973858] [<ffffffff80c3da52>] p9_virtio_init+0x36/0x56
> [    0.973887] [<ffffffff800028fe>] do_one_initcall+0x80/0x268
> [    0.973915] [<ffffffff80c01144>] kernel_init_freeable+0x296/0x300
> [    0.973944] [<ffffffff80af05dc>] kernel_init+0x1e/0x10a
> [    0.973972] [<ffffffff80afa716>] ret_from_fork+0xe/0x1c
>
>
> FWIW, the full Qemu command I used was as follows:
>
>         sudo /home/andrea/Downloads/qemu/build/qemu-system-riscv64 \
>                 -append "root=/dev/root rw rootfstype=9p rootflags=version=9p2000.L,trans=virtio,cache=mmap,access=any raid=noautodetect security=none loglevel=7" \
>                 -cpu rv64,sv57=off,svadu=off,svnapot=off \
>                 -device virtio-net-device,netdev=net0 \
>                 -device virtio-rng-device,rng=rng0 \
>                 -device virtio-9p-pci,fsdev=root,mount_tag=/dev/root \
>                 -fsdev local,id=root,path=/home/andrea/Downloads/jammy/,security_model=none \
>                 -kernel /home/andrea/linux/arch/riscv/boot/Image \
>                 -m 16G \
>                 -machine virt,aia=<either "none" or "aplic-imsic"> \
>                 -monitor telnet:127.0.0.1:55555,server,nowait \
>                 -netdev user,id=net0,host=10.0.2.10,hostfwd=tcp::10022-:22 \
>                 -nographic \
>                 -object rng-random,filename=/dev/urandom,id=rng0 \
>                 -serial mon:stdio \
>                 -smp 5
>
>
>   Andrea

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