1. 17 Jul, 2018 4 commits
    • Paul Burton's avatar
      MIPS: Use async IPIs for arch_trigger_cpumask_backtrace() · 0818c44b
      Paul Burton authored
      commit b63e132b upstream.
      
      The current MIPS implementation of arch_trigger_cpumask_backtrace() is
      broken because it attempts to use synchronous IPIs despite the fact that
      it may be run with interrupts disabled.
      
      This means that when arch_trigger_cpumask_backtrace() is invoked, for
      example by the RCU CPU stall watchdog, we may:
      
        - Deadlock due to use of synchronous IPIs with interrupts disabled,
          causing the CPU that's attempting to generate the backtrace output
          to hang itself.
      
        - Not succeed in generating the desired output from remote CPUs.
      
        - Produce warnings about this from smp_call_function_many(), for
          example:
      
          [42760.526910] INFO: rcu_sched detected stalls on CPUs/tasks:
          [42760.535755]  0-...!: (1 GPs behind) idle=ade/140000000000000/0 softirq=526944/526945 fqs=0
          [42760.547874]  1-...!: (0 ticks this GP) idle=e4a/140000000000000/0 softirq=547885/547885 fqs=0
          [42760.559869]  (detected by 2, t=2162 jiffies, g=266689, c=266688, q=33)
          [42760.568927] ------------[ cut here ]------------
          [42760.576146] WARNING: CPU: 2 PID: 1216 at kernel/smp.c:416 smp_call_function_many+0x88/0x20c
          [42760.587839] Modules linked in:
          [42760.593152] CPU: 2 PID: 1216 Comm: sh Not tainted 4.15.4-00373-gee058bb4d0c2 #2
          [42760.603767] Stack : 8e09bd20 8e09bd20 8e09bd20 fffffff0 00000007 00000006 00000000 8e09bca8
          [42760.616937]         95b2b379 95b2b379 807a0080 00000007 81944518 0000018a 00000032 00000000
          [42760.630095]         00000000 00000030 80000000 00000000 806eca74 00000009 8017e2b8 000001a0
          [42760.643169]         00000000 00000002 00000000 8e09baa4 00000008 808b8008 86d69080 8e09bca0
          [42760.656282]         8e09ad50 805e20aa 00000000 00000000 00000000 8017e2b8 00000009 801070ca
          [42760.669424]         ...
          [42760.673919] Call Trace:
          [42760.678672] [<27fde568>] show_stack+0x70/0xf0
          [42760.685417] [<84751641>] dump_stack+0xaa/0xd0
          [42760.692188] [<699d671c>] __warn+0x80/0x92
          [42760.698549] [<68915d41>] warn_slowpath_null+0x28/0x36
          [42760.705912] [<f7c76c1c>] smp_call_function_many+0x88/0x20c
          [42760.713696] [<6bbdfc2a>] arch_trigger_cpumask_backtrace+0x30/0x4a
          [42760.722216] [<f845bd33>] rcu_dump_cpu_stacks+0x6a/0x98
          [42760.729580] [<796e7629>] rcu_check_callbacks+0x672/0x6ac
          [42760.737476] [<059b3b43>] update_process_times+0x18/0x34
          [42760.744981] [<6eb94941>] tick_sched_handle.isra.5+0x26/0x38
          [42760.752793] [<478d3d70>] tick_sched_timer+0x1c/0x50
          [42760.759882] [<e56ea39f>] __hrtimer_run_queues+0xc6/0x226
          [42760.767418] [<e88bbcae>] hrtimer_interrupt+0x88/0x19a
          [42760.775031] [<6765a19e>] gic_compare_interrupt+0x2e/0x3a
          [42760.782761] [<0558bf5f>] handle_percpu_devid_irq+0x78/0x168
          [42760.790795] [<90c11ba2>] generic_handle_irq+0x1e/0x2c
          [42760.798117] [<1b6d462c>] gic_handle_local_int+0x38/0x86
          [42760.805545] [<b2ada1c7>] gic_irq_dispatch+0xa/0x14
          [42760.812534] [<90c11ba2>] generic_handle_irq+0x1e/0x2c
          [42760.820086] [<c7521934>] do_IRQ+0x16/0x20
          [42760.826274] [<9aef3ce6>] plat_irq_dispatch+0x62/0x94
          [42760.833458] [<6a94b53c>] except_vec_vi_end+0x70/0x78
          [42760.840655] [<22284043>] smp_call_function_many+0x1ba/0x20c
          [42760.848501] [<54022b58>] smp_call_function+0x1e/0x2c
          [42760.855693] [<ab9fc705>] flush_tlb_mm+0x2a/0x98
          [42760.862730] [<0844cdd0>] tlb_flush_mmu+0x1c/0x44
          [42760.869628] [<cb259b74>] arch_tlb_finish_mmu+0x26/0x3e
          [42760.877021] [<1aeaaf74>] tlb_finish_mmu+0x18/0x66
          [42760.883907] [<b3fce717>] exit_mmap+0x76/0xea
          [42760.890428] [<c4c8a2f6>] mmput+0x80/0x11a
          [42760.896632] [<a41a08f4>] do_exit+0x1f4/0x80c
          [42760.903158] [<ee01cef6>] do_group_exit+0x20/0x7e
          [42760.909990] [<13fa8d54>] __wake_up_parent+0x0/0x1e
          [42760.917045] [<46cf89d0>] smp_call_function_many+0x1a2/0x20c
          [42760.924893] [<8c21a93b>] syscall_common+0x14/0x1c
          [42760.931765] ---[ end trace 02aa09da9dc52a60 ]---
          [42760.938342] ------------[ cut here ]------------
          [42760.945311] WARNING: CPU: 2 PID: 1216 at kernel/smp.c:291 smp_call_function_single+0xee/0xf8
          ...
      
      This patch switches MIPS' arch_trigger_cpumask_backtrace() to use async
      IPIs & smp_call_function_single_async() in order to resolve this
      problem. We ensure use of the pre-allocated call_single_data_t
      structures is serialized by maintaining a cpumask indicating that
      they're busy, and refusing to attempt to send an IPI when a CPU's bit is
      set in this mask. This should only happen if a CPU hasn't responded to a
      previous backtrace IPI - ie. if it's hung - and we print a warning to
      the console in this case.
      
      I've marked this for stable branches as far back as v4.9, to which it
      applies cleanly. Strictly speaking the faulty MIPS implementation can be
      traced further back to commit 856839b7 ("MIPS: Add
      arch_trigger_all_cpu_backtrace() function") in v3.19, but kernel
      versions v3.19 through v4.8 will require further work to backport due to
      the rework performed in commit 9a01c3ed ("nmi_backtrace: add more
      trigger_*_cpu_backtrace() methods").
      Signed-off-by: default avatarPaul Burton <paul.burton@mips.com>
      Patchwork: https://patchwork.linux-mips.org/patch/19597/
      Cc: James Hogan <jhogan@kernel.org>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Huacai Chen <chenhc@lemote.com>
      Cc: linux-mips@linux-mips.org
      Cc: stable@vger.kernel.org # v4.9+
      Fixes: 856839b7 ("MIPS: Add arch_trigger_all_cpu_backtrace() function")
      Fixes: 9a01c3ed ("nmi_backtrace: add more trigger_*_cpu_backtrace() methods")
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0818c44b
    • Paul Burton's avatar
      MIPS: Call dump_stack() from show_regs() · 14ab9902
      Paul Burton authored
      commit 5a267832 upstream.
      
      The generic nmi_cpu_backtrace() function calls show_regs() when a struct
      pt_regs is available, and dump_stack() otherwise. If we were to make use
      of the generic nmi_cpu_backtrace() with MIPS' current implementation of
      show_regs() this would mean that we see only register data with no
      accompanying stack information, in contrast with our current
      implementation which calls dump_stack() regardless of whether register
      state is available.
      
      In preparation for making use of the generic nmi_cpu_backtrace() to
      implement arch_trigger_cpumask_backtrace(), have our implementation of
      show_regs() call dump_stack() and drop the explicit dump_stack() call in
      arch_dump_stack() which is invoked by arch_trigger_cpumask_backtrace().
      
      This will allow the output we produce to remain the same after a later
      patch switches to using nmi_cpu_backtrace(). It may mean that we produce
      extra stack output in other uses of show_regs(), but this:
      
        1) Seems harmless.
        2) Is good for consistency between arch_trigger_cpumask_backtrace()
           and other users of show_regs().
        3) Matches the behaviour of the ARM & PowerPC architectures.
      
      Marked for stable back to v4.9 as a prerequisite of the following patch
      "MIPS: Call dump_stack() from show_regs()".
      Signed-off-by: default avatarPaul Burton <paul.burton@mips.com>
      Patchwork: https://patchwork.linux-mips.org/patch/19596/
      Cc: James Hogan <jhogan@kernel.org>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Huacai Chen <chenhc@lemote.com>
      Cc: linux-mips@linux-mips.org
      Cc: stable@vger.kernel.org # v4.9+
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      14ab9902
    • Kai Chieh Chuang's avatar
      ASoC: mediatek: preallocate pages use platform device · 77f738e8
      Kai Chieh Chuang authored
      commit 5845e615 upstream.
      
      preallocate pages should use platform device,
      since we set dma mask for platform device.
      Signed-off-by: default avatarKaiChieh Chuang <kaichieh.chuang@mediatek.com>
      Signed-off-by: default avatarMark Brown <broonie@kernel.org>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarSudip Mukherjee <sudipm.mukherjee@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      
      77f738e8
    • Sean Young's avatar
      media: rc: mce_kbd decoder: fix stuck keys · 99ebaf4f
      Sean Young authored
      commit 63039c29 upstream.
      
      The MCE Remote sends a 0 scancode when keys are released. If this is not
      received or decoded, then keys can get "stuck"; the keyup event is not
      sent since the input_sync() is missing from the timeout handler.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarSean Young <sean@mess.org>
      Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
      Signed-off-by: default avatarSudip Mukherjee <sudipm.mukherjee@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      99ebaf4f
  2. 11 Jul, 2018 36 commits