From patchwork Tue Oct 30 11:35:44 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anders Roxell X-Patchwork-Id: 149738 Delivered-To: patch@linaro.org Received: by 2002:a2e:299d:0:0:0:0:0 with SMTP id p29-v6csp5333277ljp; Tue, 30 Oct 2018 04:36:13 -0700 (PDT) X-Google-Smtp-Source: AJdET5dAPmzkT0V8h/I6D22mb+OzqFGT3VviO25mN+/rlEBqQLN6kdvCe0nKvlnqX5k6Juu2/lmG X-Received: by 2002:a65:4783:: with SMTP id e3-v6mr17325630pgs.12.1540899372956; Tue, 30 Oct 2018 04:36:12 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1540899372; cv=none; d=google.com; s=arc-20160816; b=fOzMQ0jpZmudDxqL0Rmhy7YZm/wTYrOCPtyRUOLg3e5v1TxS0VYcvuahPPCznyhOuS MCRZkbPDOZXmrQY52uBvhA8FYe7ki8A3/hdEjUiYtYNO2v9lNozpbUnG89gJR0Uj0vNx jEaWzFR05FXgLqqyqPafaQXqTH34mMy7DQhFwL02NQvG7JQaQfmwSuckuDiMA39rMJ6v UACRUQf8aD8Xeq11Zpr/A5Qe8pMEnIJ091jxweNbCpeG7IiflXLA1dIshSZNKRuRv22U DVn26BTXKpOS2pRA7hl5e1aat6GxkNs5MMUrsrtnN5UK+l1NcQPmbK3g+HzWbbmGU2EG i/ag== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature; bh=WJ322NJYt3KCJHxHGLXAnFMT7Facd4rpzlJUcFGlM1E=; b=ff9xNH6ZHS2BbW5LS8razZ0lXb2GYYISjH0Qb/VbSbzrjd+w8XFYKhJTf1ZkAvdVRk PHaUQ34PaH0REqzslEgO7or3zTTX08RucuNZYl6qhXCo35u/RGtrAuSsdRFTyiTMFPvE MI/0oMXxt39Xsy7ISMyTXfiZQwUfRn3iSp1BHxAlIxXgsQgPg118yJWsdBaXLd6Hu0+b rMdB1l28EgtDuwHbyV0BhOqcQFODn7lfjm297dp0Lp86KGCR3GjCYpfEjf6h1IpgXHEw Sg7KbmSxBBD8r/xd20CBes7alQNgX9wDr5UKYyvf/YRHEi0XGPgpRVsoZR37uL9BCGxB OMBg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b="C/OUWmrn"; spf=pass (google.com: best guess record for domain of linux-serial-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-serial-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. 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[213.113.33.115]) by smtp.gmail.com with ESMTPSA id j66-v6sm3749434ljb.45.2018.10.30.04.36.08 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 30 Oct 2018 04:36:08 -0700 (PDT) From: Anders Roxell To: linux@armlinux.org.uk, gregkh@linuxfoundation.org, akpm@linux-foundation.org Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, tj@kernel.org, Anders Roxell , Arnd Bergmann Subject: [PATCH v2 1/2] serial: set suppress_bind_attrs flag only if builtin Date: Tue, 30 Oct 2018 12:35:44 +0100 Message-Id: <20181030113545.30999-1-anders.roxell@linaro.org> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org When the test 'CONFIG_DEBUG_TEST_DRIVER_REMOVE=y' is enabled, arch_initcall(pl011_init) came before subsys_initcall(default_bdi_init). devtmpfs gets killed because we try to remove a file and decrement the wb reference count before the noop_backing_device_info gets initialized. [ 0.332075] Serial: AMBA PL011 UART driver [ 0.485276] 9000000.pl011: ttyAMA0 at MMIO 0x9000000 (irq = 39, base_baud = 0) is a PL011 rev1 [ 0.502382] console [ttyAMA0] enabled [ 0.515710] Unable to handle kernel paging request at virtual address 0000800074c12000 [ 0.516053] Mem abort info: [ 0.516222] ESR = 0x96000004 [ 0.516417] Exception class = DABT (current EL), IL = 32 bits [ 0.516641] SET = 0, FnV = 0 [ 0.516826] EA = 0, S1PTW = 0 [ 0.516984] Data abort info: [ 0.517149] ISV = 0, ISS = 0x00000004 [ 0.517339] CM = 0, WnR = 0 [ 0.517553] [0000800074c12000] user address but active_mm is swapper [ 0.517928] Internal error: Oops: 96000004 [#1] PREEMPT SMP [ 0.518305] Modules linked in: [ 0.518839] CPU: 0 PID: 13 Comm: kdevtmpfs Not tainted 4.19.0-rc5-next-20180928-00002-g2ba39ab0cd01-dirty #82 [ 0.519307] Hardware name: linux,dummy-virt (DT) [ 0.519681] pstate: 80000005 (Nzcv daif -PAN -UAO) [ 0.519959] pc : __destroy_inode+0x94/0x2a8 [ 0.520212] lr : __destroy_inode+0x78/0x2a8 [ 0.520401] sp : ffff0000098c3b20 [ 0.520590] x29: ffff0000098c3b20 x28: 00000000087a3714 [ 0.520904] x27: 0000000000002000 x26: 0000000000002000 [ 0.521179] x25: ffff000009583000 x24: 0000000000000000 [ 0.521467] x23: ffff80007bb52000 x22: ffff80007bbaa7c0 [ 0.521737] x21: ffff0000093f9338 x20: 0000000000000000 [ 0.522033] x19: ffff80007bbb05d8 x18: 0000000000000400 [ 0.522376] x17: 0000000000000000 x16: 0000000000000000 [ 0.522727] x15: 0000000000000400 x14: 0000000000000400 [ 0.523068] x13: 0000000000000001 x12: 0000000000000001 [ 0.523421] x11: 0000000000000000 x10: 0000000000000970 [ 0.523749] x9 : ffff0000098c3a60 x8 : ffff80007bbab190 [ 0.524017] x7 : ffff80007bbaa880 x6 : 0000000000000c88 [ 0.524305] x5 : ffff0000093d96c8 x4 : 61c8864680b583eb [ 0.524567] x3 : ffff0000093d6180 x2 : ffffffffffffffff [ 0.524872] x1 : 0000800074c12000 x0 : 0000800074c12000 [ 0.525207] Process kdevtmpfs (pid: 13, stack limit = 0x(____ptrval____)) [ 0.525529] Call trace: [ 0.525806] __destroy_inode+0x94/0x2a8 [ 0.526108] destroy_inode+0x34/0x88 [ 0.526370] evict+0x144/0x1c8 [ 0.526636] iput+0x184/0x230 [ 0.526871] dentry_unlink_inode+0x118/0x130 [ 0.527152] d_delete+0xd8/0xe0 [ 0.527420] vfs_unlink+0x240/0x270 [ 0.527665] handle_remove+0x1d8/0x330 [ 0.527875] devtmpfsd+0x138/0x1c8 [ 0.528085] kthread+0x14c/0x158 [ 0.528291] ret_from_fork+0x10/0x18 [ 0.528720] Code: 92800002 aa1403e0 d538d081 8b010000 (c85f7c04) [ 0.529367] ---[ end trace 5a3dee47727f877c ]--- Rework to set suppress_bind_attrs flag to avoid removing the device when CONFIG_DEBUG_TEST_DRIVER_REMOVE=y. This applies for pic32_uart and xilinx_uartps as well. Co-developed-by: Arnd Bergmann Signed-off-by: Arnd Bergmann Signed-off-by: Anders Roxell --- drivers/tty/serial/amba-pl011.c | 2 ++ drivers/tty/serial/pic32_uart.c | 1 + drivers/tty/serial/xilinx_uartps.c | 1 + 3 files changed, 4 insertions(+) -- 2.19.1 diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index ebd33c0232e6..89ade213a1a9 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -2780,6 +2780,7 @@ static struct platform_driver arm_sbsa_uart_platform_driver = { .name = "sbsa-uart", .of_match_table = of_match_ptr(sbsa_uart_of_match), .acpi_match_table = ACPI_PTR(sbsa_uart_acpi_match), + .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_AMBA_PL011), }, }; @@ -2808,6 +2809,7 @@ static struct amba_driver pl011_driver = { .drv = { .name = "uart-pl011", .pm = &pl011_dev_pm_ops, + .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_AMBA_PL011), }, .id_table = pl011_ids, .probe = pl011_probe, diff --git a/drivers/tty/serial/pic32_uart.c b/drivers/tty/serial/pic32_uart.c index fd80d999308d..0bdf1687983f 100644 --- a/drivers/tty/serial/pic32_uart.c +++ b/drivers/tty/serial/pic32_uart.c @@ -919,6 +919,7 @@ static struct platform_driver pic32_uart_platform_driver = { .driver = { .name = PIC32_DEV_NAME, .of_match_table = of_match_ptr(pic32_serial_dt_ids), + .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_PIC32), }, }; diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index 57c66d2c3471..379242b96790 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -1719,6 +1719,7 @@ static struct platform_driver cdns_uart_platform_driver = { .name = CDNS_UART_NAME, .of_match_table = cdns_uart_of_match, .pm = &cdns_uart_dev_pm_ops, + .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_XILINX_PS_UART), }, }; From patchwork Tue Oct 30 11:35:45 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anders Roxell X-Patchwork-Id: 149739 Delivered-To: patch@linaro.org Received: by 2002:a2e:299d:0:0:0:0:0 with SMTP id p29-v6csp5333643ljp; Tue, 30 Oct 2018 04:36:36 -0700 (PDT) X-Google-Smtp-Source: AJdET5e3pKUt+Lp5WVZdYIS8B3EuGIZWJg8oOg4ygwZjAHmyCURnE99LEM9dcLomocbER4sbUyhq X-Received: by 2002:a63:c00b:: with SMTP id h11-v6mr17840162pgg.159.1540899396240; Tue, 30 Oct 2018 04:36:36 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1540899396; cv=none; d=google.com; s=arc-20160816; b=vnDhbmhHfUVZh2WqjOYW1XDBrdchb0Q8WKrT58r1FYOYgtslmq1Xm4YbyvAbSraRUT ekY0axaWy5/d3KKw1EGlFB4Xz2eqhiBMTFzyAfg3XwZidXlNXpPzHdonb407IwoEF/sp PP0b13Zi2ZX/8mUNaKwcMumpvY+5z0ZZIq7Knc1RqAMCfIQbP8w6LfzDwssqX7CYnBIX 6IM2u9lPboHsKsp5lCWblIGglBGM7gsIpQRCiHxP2akS8UXBfR6I6lEBRhjMNndnaTnI WQrMWBqHietstTARfyvzrczzpRzt8fbrFL9bKY6UaRd2t8RbMEzOfqdp6jbSj+yCJqRq 4ACA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=0c4qq4Ww0v5TJSITOLozxcLN7WvXMS6Pv+NS1rx0eYU=; b=b8xfyOKQ0Sxyaa1upVjftrn91c2HxZHnFTj4WCXWSrcJmw5FjsPu65TuwtbOUyrNGb NBcjKYdt8goCAhLyqpfCu/gGEsmbYp5RLpWXHQ2TUN/fttgB9PyfL8rM/PB8S6ujZozB 6GUGBnyfcJJGLPaVjLKku4FhJ2jiq3YORMgVjydNcVf91YQ6aLD9NANHfTD8u2kbNJzs sEhY6EXGkF0IbHj6zYPeLQMC9uv2ixF+El8FE9UwgiChbGq6iKIjL+i/13L3C6+V25ij cCJSyuatcylnJxal1bsMPzQKxM7JqaMa36NhZwxH9Vx/QdyJpUlYrBdHrZhOsOFjmckT C8MQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=gOwgddOR; spf=pass (google.com: best guess record for domain of linux-serial-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-serial-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. 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[213.113.33.115]) by smtp.gmail.com with ESMTPSA id l67-v6sm3776781lfg.45.2018.10.30.04.36.32 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 30 Oct 2018 04:36:32 -0700 (PDT) From: Anders Roxell To: linux@armlinux.org.uk, gregkh@linuxfoundation.org, akpm@linux-foundation.org Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, tj@kernel.org, Anders Roxell , Arnd Bergmann Subject: [PATCH v2 2/2] writeback: don't decrement wb->refcnt if !wb->bdi Date: Tue, 30 Oct 2018 12:35:45 +0100 Message-Id: <20181030113545.30999-2-anders.roxell@linaro.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181030113545.30999-1-anders.roxell@linaro.org> References: <20181030113545.30999-1-anders.roxell@linaro.org> MIME-Version: 1.0 Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org This happened while running in qemu-system-aarch64, the AMBA PL011 UART driver when enabling CONFIG_DEBUG_TEST_DRIVER_REMOVE. arch_initcall(pl011_init) came before subsys_initcall(default_bdi_init), devtmpfs' handle_remove() crashes because the reference count is a NULL pointer only because wb->bdi hasn't been initialized yet. Rework so that wb_put have an extra check if wb->bdi before decrement wb->refcnt and also add a WARN_ON_ONCE to get a warning if it happens again in other drivers. Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks") Co-developed-by: Arnd Bergmann Signed-off-by: Arnd Bergmann Signed-off-by: Anders Roxell --- include/linux/backing-dev-defs.h | 8 ++++++++ 1 file changed, 8 insertions(+) -- 2.19.1 diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index 9a6bc0951cfa..c31157135598 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -258,6 +258,14 @@ static inline void wb_get(struct bdi_writeback *wb) */ static inline void wb_put(struct bdi_writeback *wb) { + if (WARN_ON_ONCE(!wb->bdi)) { + /* + * A driver bug might cause a file to be removed before bdi was + * initialized. + */ + return; + } + if (wb != &wb->bdi->wb) percpu_ref_put(&wb->refcnt); }