From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <54986525.3070305@codeaurora.org> Date: Mon, 22 Dec 2014 10:38:29 -0800 From: Stephen Boyd MIME-Version: 1.0 To: Krzysztof Kozlowski , Mike Turquette , linux-kernel@vger.kernel.org CC: Rajendra Nayak , Kyungmin Park , Marek Szyprowski , Bartlomiej Zolnierkiewicz , stable@vger.kernel.org Subject: Re: [PATCH] clk: Fix __GFP_FS allocation with irqs disabled References: <1419248747-3367-1-git-send-email-k.kozlowski@samsung.com> In-Reply-To: <1419248747-3367-1-git-send-email-k.kozlowski@samsung.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: On 12/22/2014 03:45 AM, Krzysztof Kozlowski wrote: > Allocation of memory for cached clock parents during s3c-sdhci probe was > done with interrupts disabled which lead to lockdep warning: > > [ 2.254980] s3c-sdhci 12530000.sdhci: clock source 2: mmc_busclk.2 (50000000 Hz) > [ 2.560726] ------------[ cut here ]------------ > [ 2.565341] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2744 lockdep_trace_alloc+0xec/0x118() > [ 2.574439] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) > [ 2.579821] Modules linked in: > [ 2.583038] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 3.18.0-next-20141216-00002-g4ff197fc1902-dirty #1318 > [ 2.593796] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) > [ 2.599892] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [ 2.607612] [] (show_stack) from [] (dump_stack+0x70/0xbc) > [ 2.614822] [] (dump_stack) from [] (warn_slowpath_common+0x74/0xb0) > [ 2.622885] [] (warn_slowpath_common) from [] (warn_slowpath_fmt+0x30/0x40) > [ 2.631569] [] (warn_slowpath_fmt) from [] (lockdep_trace_alloc+0xec/0x118) > [ 2.640246] [] (lockdep_trace_alloc) from [] (__kmalloc+0x3c/0x1cc) > [ 2.648240] [] (__kmalloc) from [] (clk_fetch_parent_index+0xb8/0xd4) > [ 2.656390] [] (clk_fetch_parent_index) from [] (clk_calc_new_rates+0xe0/0x1fc) > [ 2.665415] [] (clk_calc_new_rates) from [] (clk_calc_new_rates+0x1b4/0x1fc) > [ 2.674181] [] (clk_calc_new_rates) from [] (clk_set_rate+0x50/0xc8) > [ 2.682265] [] (clk_set_rate) from [] (sdhci_cmu_set_clock+0x68/0x16c) clk_set_rate() takes a mutex, so that looks to be the real problem here. Don't call clk_set_rate() in a context where irqs are disabled. > [ 2.690503] [] (sdhci_cmu_set_clock) from [] (sdhci_do_set_ios+0xf0/0x64c) > [ 2.699095] [] (sdhci_do_set_ios) from [] (sdhci_set_ios+0x20/0x2c) > [ 2.707080] [] (sdhci_set_ios) from [] (mmc_power_up+0x118/0x1fc) > [ 2.714889] [] (mmc_power_up) from [] (mmc_start_host+0x44/0x6c) > [ 2.722615] [] (mmc_start_host) from [] (mmc_add_host+0x58/0x7c) > [ 2.730341] [] (mmc_add_host) from [] (sdhci_add_host+0x968/0xd94) > [ 2.738240] [] (sdhci_add_host) from [] (sdhci_s3c_probe+0x354/0x52c) > [ 2.746406] [] (sdhci_s3c_probe) from [] (platform_drv_probe+0x48/0xa4) > [ 2.754733] [] (platform_drv_probe) from [] (driver_probe_device+0x13c/0x37c) > [ 2.763585] [] (driver_probe_device) from [] (__driver_attach+0x94/0x98) > [ 2.772003] [] (__driver_attach) from [] (bus_for_each_dev+0x54/0x88) > [ 2.780163] [] (bus_for_each_dev) from [] (bus_add_driver+0xe4/0x200) > [ 2.788322] [] (bus_add_driver) from [] (driver_register+0x78/0xf4) > [ 2.796308] [] (driver_register) from [] (do_one_initcall+0xac/0x1f0) > [ 2.804473] [] (do_one_initcall) from [] (kernel_init_freeable+0x10c/0x1d8) > [ 2.813153] [] (kernel_init_freeable) from [] (kernel_init+0x28/0x108) > [ 2.821398] [] (kernel_init) from [] (ret_from_fork+0x14/0x2c) > [ 2.828939] ---[ end trace 03cc00e539849d1f ]--- > > The memory for cached parents was not allocated during __clk_init() > because the clock has only one parent and commit 9ca1c5a4bf41 ("clk: > cache parent clocks only for muxes") made allocation skipped in such case. > > Be consequent also in clk_fetch_parent_index(): don't cache parents if > there is only one. > > Signed-off-by: Krzysztof Kozlowski > Fixes: 9ca1c5a4bf41 ("clk: cache parent clocks only for muxes") > Cc: > --- > drivers/clk/clk.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index f4963b7d4e17..35079302a650 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -1150,6 +1150,12 @@ static int clk_fetch_parent_index(struct clk *clk, struct clk *parent) > { > int i; > > + if (clk->num_parents == 1) { > + if (IS_ERR_OR_NULL(clk->parent)) > + clk->parent = __clk_lookup(clk->parent_names[0]); > + return 0; > + } > + > if (!clk->parents) { > clk->parents = kcalloc(clk->num_parents, > sizeof(struct clk *), GFP_KERNEL); This may be a worthwhile optimization, but I wonder why the clk_ops for this clock need to fetch the parent index at all? Which clock are we actually dealing with here? -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project