From nobody Thu Feb 12 02:00:20 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D156FEE0203 for ; Thu, 14 Sep 2023 01:56:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234183AbjINB4w (ORCPT ); Wed, 13 Sep 2023 21:56:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234170AbjINB4D (ORCPT ); Wed, 13 Sep 2023 21:56:03 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F9582127; Wed, 13 Sep 2023 18:55:47 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B94BDC433C7; Thu, 14 Sep 2023 01:55:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1694656546; bh=LZ6DzAt5mVz1QiKYVFmaZ9L+EBTYTuGsjlufbB5PfBc=; h=From:To:Cc:Subject:Date:From; b=TNhCUyPMFdmf4ldrxH2gpfnSez5Dxozru0j13G/IqzTtos6IOPc98JhzJV4YRiQla aplc+YwA47KFoi3dnedH1Tgugl+CZCJ9bTOQ7zQ6y4OEFdiIzQGXuZx70J9bgL6B3y nAqvCHfBiUukznAOA7lNXxuOuwOpMOmdNydaqZ68XUmELoWevfdasIh+PsfBP6pdyh kYqHu3+CiMcPRRUKNfxBkr+WixHN+AkJhF0SXrnnHuqoft4jGGyeXkYr0WlmYTqWtz 1ksErfHk4Zak435oO1PObnAvt1ULaezzg8WyTEUQoNdt5p3G9dJ87CqYLT9V1Q2I9b wZI0c9g4X6Nyg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sergey Senozhatsky , Rob Clark , Robin Murphy , Christoph Hellwig , Sasha Levin , m.szyprowski@samsung.com, iommu@lists.linux.dev Subject: [PATCH AUTOSEL 5.10] dma-debug: don't call __dma_entry_alloc_check_leak() under free_entries_lock Date: Wed, 13 Sep 2023 21:55:43 -0400 Message-Id: <20230914015543.52035-1-sashal@kernel.org> X-Mailer: git-send-email 2.40.1 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.10.194 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Sergey Senozhatsky [ Upstream commit fb5a4315591dae307a65fc246ca80b5159d296e1 ] __dma_entry_alloc_check_leak() calls into printk -> serial console output (qcom geni) and grabs port->lock under free_entries_lock spin lock, which is a reverse locking dependency chain as qcom_geni IRQ handler can call into dma-debug code and grab free_entries_lock under port->lock. Move __dma_entry_alloc_check_leak() call out of free_entries_lock scope so that we don't acquire serial console's port->lock under it. Trimmed-down lockdep splat: The existing dependency chain (in reverse order) is: -> #2 (free_entries_lock){-.-.}-{2:2}: _raw_spin_lock_irqsave+0x60/0x80 dma_entry_alloc+0x38/0x110 debug_dma_map_page+0x60/0xf8 dma_map_page_attrs+0x1e0/0x230 dma_map_single_attrs.constprop.0+0x6c/0xc8 geni_se_rx_dma_prep+0x40/0xcc qcom_geni_serial_isr+0x310/0x510 __handle_irq_event_percpu+0x110/0x244 handle_irq_event_percpu+0x20/0x54 handle_irq_event+0x50/0x88 handle_fasteoi_irq+0xa4/0xcc handle_irq_desc+0x28/0x40 generic_handle_domain_irq+0x24/0x30 gic_handle_irq+0xc4/0x148 do_interrupt_handler+0xa4/0xb0 el1_interrupt+0x34/0x64 el1h_64_irq_handler+0x18/0x24 el1h_64_irq+0x64/0x68 arch_local_irq_enable+0x4/0x8 ____do_softirq+0x18/0x24 ... -> #1 (&port_lock_key){-.-.}-{2:2}: _raw_spin_lock_irqsave+0x60/0x80 qcom_geni_serial_console_write+0x184/0x1dc console_flush_all+0x344/0x454 console_unlock+0x94/0xf0 vprintk_emit+0x238/0x24c vprintk_default+0x3c/0x48 vprintk+0xb4/0xbc _printk+0x68/0x90 register_console+0x230/0x38c uart_add_one_port+0x338/0x494 qcom_geni_serial_probe+0x390/0x424 platform_probe+0x70/0xc0 really_probe+0x148/0x280 __driver_probe_device+0xfc/0x114 driver_probe_device+0x44/0x100 __device_attach_driver+0x64/0xdc bus_for_each_drv+0xb0/0xd8 __device_attach+0xe4/0x140 device_initial_probe+0x1c/0x28 bus_probe_device+0x44/0xb0 device_add+0x538/0x668 of_device_add+0x44/0x50 of_platform_device_create_pdata+0x94/0xc8 of_platform_bus_create+0x270/0x304 of_platform_populate+0xac/0xc4 devm_of_platform_populate+0x60/0xac geni_se_probe+0x154/0x160 platform_probe+0x70/0xc0 ... -> #0 (console_owner){-...}-{0:0}: __lock_acquire+0xdf8/0x109c lock_acquire+0x234/0x284 console_flush_all+0x330/0x454 console_unlock+0x94/0xf0 vprintk_emit+0x238/0x24c vprintk_default+0x3c/0x48 vprintk+0xb4/0xbc _printk+0x68/0x90 dma_entry_alloc+0xb4/0x110 debug_dma_map_sg+0xdc/0x2f8 __dma_map_sg_attrs+0xac/0xe4 dma_map_sgtable+0x30/0x4c get_pages+0x1d4/0x1e4 [msm] msm_gem_pin_pages_locked+0x38/0xac [msm] msm_gem_pin_vma_locked+0x58/0x88 [msm] msm_ioctl_gem_submit+0xde4/0x13ac [msm] drm_ioctl_kernel+0xe0/0x15c drm_ioctl+0x2e8/0x3f4 vfs_ioctl+0x30/0x50 ... Chain exists of: console_owner --> &port_lock_key --> free_entries_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(free_entries_lock); lock(&port_lock_key); lock(free_entries_lock); lock(console_owner); *** DEADLOCK *** Call trace: dump_backtrace+0xb4/0xf0 show_stack+0x20/0x30 dump_stack_lvl+0x60/0x84 dump_stack+0x18/0x24 print_circular_bug+0x1cc/0x234 check_noncircular+0x78/0xac __lock_acquire+0xdf8/0x109c lock_acquire+0x234/0x284 console_flush_all+0x330/0x454 console_unlock+0x94/0xf0 vprintk_emit+0x238/0x24c vprintk_default+0x3c/0x48 vprintk+0xb4/0xbc _printk+0x68/0x90 dma_entry_alloc+0xb4/0x110 debug_dma_map_sg+0xdc/0x2f8 __dma_map_sg_attrs+0xac/0xe4 dma_map_sgtable+0x30/0x4c get_pages+0x1d4/0x1e4 [msm] msm_gem_pin_pages_locked+0x38/0xac [msm] msm_gem_pin_vma_locked+0x58/0x88 [msm] msm_ioctl_gem_submit+0xde4/0x13ac [msm] drm_ioctl_kernel+0xe0/0x15c drm_ioctl+0x2e8/0x3f4 vfs_ioctl+0x30/0x50 ... Reported-by: Rob Clark Signed-off-by: Sergey Senozhatsky Acked-by: Robin Murphy Signed-off-by: Christoph Hellwig Signed-off-by: Sasha Levin --- kernel/dma/debug.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index ae9fc1ee6d206..0263983089097 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -606,15 +606,19 @@ static struct dma_debug_entry *__dma_entry_alloc(void) return entry; } =20 -static void __dma_entry_alloc_check_leak(void) +/* + * This should be called outside of free_entries_lock scope to avoid poten= tial + * deadlocks with serial consoles that use DMA. + */ +static void __dma_entry_alloc_check_leak(u32 nr_entries) { - u32 tmp =3D nr_total_entries % nr_prealloc_entries; + u32 tmp =3D nr_entries % nr_prealloc_entries; =20 /* Shout each time we tick over some multiple of the initial pool */ if (tmp < DMA_DEBUG_DYNAMIC_ENTRIES) { pr_info("dma_debug_entry pool grown to %u (%u00%%)\n", - nr_total_entries, - (nr_total_entries / nr_prealloc_entries)); + nr_entries, + (nr_entries / nr_prealloc_entries)); } } =20 @@ -625,8 +629,10 @@ static void __dma_entry_alloc_check_leak(void) */ static struct dma_debug_entry *dma_entry_alloc(void) { + bool alloc_check_leak =3D false; struct dma_debug_entry *entry; unsigned long flags; + u32 nr_entries; =20 spin_lock_irqsave(&free_entries_lock, flags); if (num_free_entries =3D=3D 0) { @@ -636,13 +642,17 @@ static struct dma_debug_entry *dma_entry_alloc(void) pr_err("debugging out of memory - disabling\n"); return NULL; } - __dma_entry_alloc_check_leak(); + alloc_check_leak =3D true; + nr_entries =3D nr_total_entries; } =20 entry =3D __dma_entry_alloc(); =20 spin_unlock_irqrestore(&free_entries_lock, flags); =20 + if (alloc_check_leak) + __dma_entry_alloc_check_leak(nr_entries); + #ifdef CONFIG_STACKTRACE entry->stack_len =3D stack_trace_save(entry->stack_entries, ARRAY_SIZE(entry->stack_entries), --=20 2.40.1