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Tue, 10 Mar 2020 18:49:30 +0000 From: Marc Zyngier To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 4/4] irqchip/gic-v4: Provide irq_retrigger to avoid circular locking dependency Date: Tue, 10 Mar 2020 18:49:21 +0000 Message-Id: <20200310184921.23552-5-maz@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200310184921.23552-1-maz@kernel.org> References: <20200310184921.23552-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, tglx@linutronix.de, jason@lakedaemon.net, linux@arm.linux.org.uk, nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com, ludovic.desroches@microchip.com, yuzenghui@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200310_114932_795082_E1C1D78D X-CRM114-Status: GOOD ( 16.52 ) X-Spam-Score: -5.2 (-----) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-5.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexandre Belloni , Russell King , Jason Cooper , Ludovic Desroches , Zenghui Yu , Thomas Gleixner Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org On a very heavily loaded D05 with GICv4, I managed to trigger the following lockdep splat: [ 6022.598864] ====================================================== [ 6022.605031] WARNING: possible circular locking dependency detected [ 6022.611200] 5.6.0-rc4-00026-geee7c7b0f498 #680 Tainted: G E [ 6022.618061] ------------------------------------------------------ [ 6022.624227] qemu-system-aar/7569 is trying to acquire lock: [ 6022.629789] ffff042f97606808 (&p->pi_lock){-.-.}, at: try_to_wake_up+0x54/0x7a0 [ 6022.637102] [ 6022.637102] but task is already holding lock: [ 6022.642921] ffff002fae424cf0 (&irq_desc_lock_class){-.-.}, at: __irq_get_desc_lock+0x5c/0x98 [ 6022.651350] [ 6022.651350] which lock already depends on the new lock. [ 6022.651350] [ 6022.659512] [ 6022.659512] the existing dependency chain (in reverse order) is: [ 6022.666980] [ 6022.666980] -> #2 (&irq_desc_lock_class){-.-.}: [ 6022.672983] _raw_spin_lock_irqsave+0x50/0x78 [ 6022.677848] __irq_get_desc_lock+0x5c/0x98 [ 6022.682453] irq_set_vcpu_affinity+0x40/0xc0 [ 6022.687236] its_make_vpe_non_resident+0x6c/0xb8 [ 6022.692364] vgic_v4_put+0x54/0x70 [ 6022.696273] vgic_v3_put+0x20/0xd8 [ 6022.700183] kvm_vgic_put+0x30/0x48 [ 6022.704182] kvm_arch_vcpu_put+0x34/0x50 [ 6022.708614] kvm_sched_out+0x34/0x50 [ 6022.712700] __schedule+0x4bc/0x7f8 [ 6022.716697] schedule+0x50/0xd8 [ 6022.720347] kvm_arch_vcpu_ioctl_run+0x5f0/0x978 [ 6022.725473] kvm_vcpu_ioctl+0x3d4/0x8f8 [ 6022.729820] ksys_ioctl+0x90/0xd0 [ 6022.733642] __arm64_sys_ioctl+0x24/0x30 [ 6022.738074] el0_svc_common.constprop.3+0xa8/0x1e8 [ 6022.743373] do_el0_svc+0x28/0x88 [ 6022.747198] el0_svc+0x14/0x40 [ 6022.750761] el0_sync_handler+0x124/0x2b8 [ 6022.755278] el0_sync+0x140/0x180 [ 6022.759100] [ 6022.759100] -> #1 (&rq->lock){-.-.}: [ 6022.764143] _raw_spin_lock+0x38/0x50 [ 6022.768314] task_fork_fair+0x40/0x128 [ 6022.772572] sched_fork+0xe0/0x210 [ 6022.776484] copy_process+0x8c4/0x18d8 [ 6022.780742] _do_fork+0x88/0x6d8 [ 6022.784478] kernel_thread+0x64/0x88 [ 6022.788563] rest_init+0x30/0x270 [ 6022.792390] arch_call_rest_init+0x14/0x1c [ 6022.796995] start_kernel+0x498/0x4c4 [ 6022.801164] [ 6022.801164] -> #0 (&p->pi_lock){-.-.}: [ 6022.806382] __lock_acquire+0xdd8/0x15c8 [ 6022.810813] lock_acquire+0xd0/0x218 [ 6022.814896] _raw_spin_lock_irqsave+0x50/0x78 [ 6022.819761] try_to_wake_up+0x54/0x7a0 [ 6022.824018] wake_up_process+0x1c/0x28 [ 6022.828276] wakeup_softirqd+0x38/0x40 [ 6022.832533] __tasklet_schedule_common+0xc4/0xf0 [ 6022.837658] __tasklet_schedule+0x24/0x30 [ 6022.842176] check_irq_resend+0xc8/0x158 [ 6022.846609] irq_startup+0x74/0x128 [ 6022.850606] __enable_irq+0x6c/0x78 [ 6022.854602] enable_irq+0x54/0xa0 [ 6022.858431] its_make_vpe_non_resident+0xa4/0xb8 [ 6022.863557] vgic_v4_put+0x54/0x70 [ 6022.867469] kvm_arch_vcpu_blocking+0x28/0x38 [ 6022.872336] kvm_vcpu_block+0x48/0x490 [ 6022.876594] kvm_handle_wfx+0x18c/0x310 [ 6022.880938] handle_exit+0x138/0x198 [ 6022.885022] kvm_arch_vcpu_ioctl_run+0x4d4/0x978 [ 6022.890148] kvm_vcpu_ioctl+0x3d4/0x8f8 [ 6022.894494] ksys_ioctl+0x90/0xd0 [ 6022.898317] __arm64_sys_ioctl+0x24/0x30 [ 6022.902748] el0_svc_common.constprop.3+0xa8/0x1e8 [ 6022.908046] do_el0_svc+0x28/0x88 [ 6022.911871] el0_svc+0x14/0x40 [ 6022.915434] el0_sync_handler+0x124/0x2b8 [ 6022.919951] el0_sync+0x140/0x180 [ 6022.923773] [ 6022.923773] other info that might help us debug this: [ 6022.923773] [ 6022.931762] Chain exists of: [ 6022.931762] &p->pi_lock --> &rq->lock --> &irq_desc_lock_class [ 6022.931762] [ 6022.942101] Possible unsafe locking scenario: [ 6022.942101] [ 6022.948007] CPU0 CPU1 [ 6022.952523] ---- ---- [ 6022.957039] lock(&irq_desc_lock_class); [ 6022.961036] lock(&rq->lock); [ 6022.966595] lock(&irq_desc_lock_class); [ 6022.973109] lock(&p->pi_lock); [ 6022.976324] [ 6022.976324] *** DEADLOCK *** This is happening because we have a pending doorbell that requires retrigger. As SW retriggering is done in a tasklet, we trigger the circular dependency above. The easy cop-out is to provide a retrigger callback that doesn't require acquiring any extra lock. Signed-off-by: Marc Zyngier --- drivers/irqchip/irq-gic-v3-its.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 83b1186ffcad..fd0758a29b5f 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -3675,12 +3675,18 @@ static int its_vpe_set_irqchip_state(struct irq_data *d, return 0; } +static int its_vpe_retrigger(struct irq_data *d) +{ + return !its_vpe_set_irqchip_state(d, IRQCHIP_STATE_PENDING, true); +} + static struct irq_chip its_vpe_irq_chip = { .name = "GICv4-vpe", .irq_mask = its_vpe_mask_irq, .irq_unmask = its_vpe_unmask_irq, .irq_eoi = irq_chip_eoi_parent, .irq_set_affinity = its_vpe_set_affinity, + .irq_retrigger = its_vpe_retrigger, .irq_set_irqchip_state = its_vpe_set_irqchip_state, .irq_set_vcpu_affinity = its_vpe_set_vcpu_affinity, };