From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x241.google.com (mail-pf0-x241.google.com [IPv6:2607:f8b0:400e:c00::241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3yd4YQ72lWzDr17 for ; Fri, 17 Nov 2017 02:15:06 +1100 (AEDT) Received: by mail-pf0-x241.google.com with SMTP id r62so7235418pfd.5 for ; Thu, 16 Nov 2017 07:15:06 -0800 (PST) Date: Fri, 17 Nov 2017 01:14:46 +1000 From: Nicholas Piggin To: Shriya Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au, paulus@samba.org, ego@linux.vnet.ibm.com, mikey@neuling.org, aneesh.kumar@linux.vnet.ibm.com Subject: Re: [PATCH] cpufreq: powernv: Return the actual CPU frequency in /proc/cpuinfo Message-ID: <20171117011446.13144fd6@roar.ozlabs.ibm.com> In-Reply-To: <1507274648-14221-1-git-send-email-shriyak@linux.vnet.ibm.com> References: <1507274648-14221-1-git-send-email-shriyak@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 6 Oct 2017 12:54:08 +0530 Shriya wrote: > Make /proc/cpuinfo read the frequency of the CPU it is running at > instead of reading the cached value of the last requested frequency. > In conditions like WOF/throttle CPU can be running at a different > frequency than the requested frequency. > > Signed-off-by: Shriya This causes the following: [ 7.203270] BUG: sleeping function called from invalid context at /home/npiggin/linux/kernel/locking/rwsem.c:23 [ 7.203323] in_atomic(): 1, irqs_disabled(): 0, pid: 1, name: systemd [ 7.203352] 1 lock held by systemd/1: [ 7.203367] #0: (&p->lock){+.+.}, at: [] seq_read+0x78/0x5c0 [ 7.203416] CPU: 164 PID: 1 Comm: systemd Not tainted 4.14.0-00345-g8fb6e339cdf5 #33 [ 7.203452] Call Trace: [ 7.203463] [c000000ff55039d0] [c000000000be4f24] dump_stack+0x104/0x190 (unreliable) [ 7.203502] [c000000ff5503a10] [c0000000001297d0] ___might_sleep+0x2e0/0x320 [ 7.203539] [c000000ff5503a90] [c000000000c049fc] down_read+0x3c/0xc0 [ 7.203569] [c000000ff5503ad0] [c0000000009f7c70] cpufreq_get+0x50/0xc0 [ 7.203600] [c000000ff5503b20] [c000000000093618] pnv_get_proc_freq+0x28/0x60 [ 7.203637] [c000000ff5503b50] [c00000000002bfc0] show_cpuinfo+0x1b0/0x460 [ 7.203667] [c000000ff5503c00] [c0000000003e14b8] seq_read+0x238/0x5c0 [ 7.203698] [c000000ff5503ca0] [c000000000441e80] proc_reg_read+0xb0/0x110 [ 7.203729] [c000000ff5503cf0] [c0000000003a16cc] __vfs_read+0x6c/0x1c0 [ 7.203759] [c000000ff5503d90] [c0000000003a18dc] vfs_read+0xbc/0x1b0 [ 7.203788] [c000000ff5503de0] [c0000000003a20cc] SyS_read+0x6c/0x110 [ 7.203819] [c000000ff5503e30] [c00000000000b82c] system_call+0x58/0x6c > arch/powerpc/platforms/powernv/setup.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c > index 897aa14..55ea4bf 100644 > --- a/arch/powerpc/platforms/powernv/setup.c > +++ b/arch/powerpc/platforms/powernv/setup.c > @@ -311,7 +311,7 @@ static unsigned long pnv_get_proc_freq(unsigned int cpu) > { > unsigned long ret_freq; > > - ret_freq = cpufreq_quick_get(cpu) * 1000ul; > + ret_freq = cpufreq_get(cpu) * 1000ul; > > /* > * If the backend cpufreq driver does not exist,