Re: [PATCH] perf: fix kernel panic when parsing user space CS saved in pt_regs

[Zhang, Yanmin]

On 2014/6/5 15:55, Peter Zijlstra wrote:
> On Thu, Jun 05, 2014 at 03:33:21PM +0800, Liu ShuoX wrote:
> > On Thu  5.Jun'14 at  9:19:19 +0200, Peter Zijlstra wrote:
> > > On Thu, Jun 05, 2014 at 10:36:10AM +0800, Liu ShuoX wrote:
> > > > From: Zhang Yanmin <yanmin.zhang@xxxxxxxxx>
> > > >
> > > > We hit a kernel panic when running perf to collect some performance data.
> > > > kenel is x86_64 and user space apps are 32bit.
> > > >
> > > > [   71.965351, 1] [       Binder_2] BUG: unable to handle kernel NULL pointer dereference at 0000000000000004
> > > > [   71.965360, 1] [       Binder_2] IP: [<ffffffff82012091>] get_segment_base+0x71/0xc0
> > > > [   71.965367, 1] [       Binder_2] PGD 6c65f067 PUD 0
> > > > [   71.965375, 1] [       Binder_2] Oops: 0000 [#1] PREEMPT SMP
> > > > [   71.965413, 1] [       Binder_2] Modules linked in: ddrgx snd_merr_dpcm_wm8958 snd_intel_sst snd_soc_sst_platform snd_soc_wm8994 snd_soc_wm_hubs lm3559 imx1x5 atomisp_css2401a0_v21 libmsrlisthelper rmi4 bcm_bt_lpm videobuf_vmalloc videobuf_core fps_throttle hdmi_audio pn544(O) tngdisp bcm4335(O) cfg80211
> > > > [   71.965420, 1] [       Binder_2] CPU: 1 PID: 304 Comm: Binder_2 Tainted: G        W  O 3.10.20-263902-g184bfbc-dirty #14
> > > > [   71.965426, 1] [       Binder_2] task: ffff8800764dc300 ti: ffff88006c6e8000 task.ti: ffff88006c6e8000
> > > > [   71.965439, 1] [       Binder_2] RIP: 0010:[<ffffffff82012091>]  [<ffffff?f82012091>] get_segment_base+0x71/0xc0
> > >                                                                              ^
> > > > [   71.965<44, 1] [       Binder_2] RSP: 0018:ffff^X8007ea87b98  EFLAGS: 00010092
> > >            ^                                       ^
> > > > [   71.965447, 1] [      !Binder_2] RAX: 0000000000000024 RBX: 0000000000000000 RCX: 0000000000000000
> > >                           ^
> > > > [   71.965450, 1] [       Binder_2] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000009
> > > > [   71.965454, 1] [       Binder_2] RBP: ffff88007ea87ba8 R08: ffffffff83143b3c R09: ffffffff831848a8
> > > > [   71.965458, 1] [       Binder_2] R10: 0000000000000000 R11: 00000000001bf2d8 R12: 0000000000000000
> > > > [   71.965462, 1] [       Binder_2] R13: ffff88006c6e9fd8 R14: ffff88006c6e9f58 R15: ffff8800764dc300
> > > > [   71.965468, 1_ [       Binder_2] FS:  0000000000000000(0000) GS:ffff88007ea80000(006b) knlGS:00000000f704add0
> > >                  ^
> > >
> > > Are you suffering some serious corruption?
> > The log captured by pstore after rebooting, so there are some
> > corruption. Please ignore those.
> Why does pstore cause corruption? I thought that stuff was supposed to
> be 'good' ?
pstore is good if the board is reset by WarmReset as memory content is 
kept across rebooting.
If it's a ColdReset, memory might lose some or all contents. My board 
uses Coldreset, which is a very
fast ColdReset. Most memory content can be kept. But sometimes, some 
data has little change.

Yanmin


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