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Date: Wed, 9 Apr 2014 13:28:16 +0800
From: Fengguang Wu <fengguang.wu@intel.com>
To: Alessandro Rubini <rubini@gnudd.com>
Cc: jet.chen@intel.com, gregkh@linuxfoundation.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [FMC] BUG: scheduling while atomic: swapper/1/0x10000002
Message-ID: <20140409052816.GA29432@localhost>
References: <5344BF60.5050300@intel.com>
 <20140409050843.GA18949@mail.gnudd.com>
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On Wed, Apr 09, 2014 at 07:08:43AM +0200, Alessandro Rubini wrote:
> Hello.
> Thank you for the report.
> 
> I'm at a conference and I fear I won't be able to test myself in the
> next days, but I think this is already fixed (it is part of
> the "misc_register" call path, so it's the same problem).
> 
> The fix is commit v3.11-rc2-11-g783c2fb
> 
>    783c2fb FMC: fix locking in sample chardev driver
> 
> This commit, however, is not part of v3.11 and I think this is why you
> are finding the problem in the v3.10..v3.11 interval.

Alessandro, you are right. There are no more "scheduling while 
atomic" bugs in v3.12 and v3.13.

Our bisect log shows

git bisect  bad 38dbfb59d1175ef458d006556061adeaa8751b72  # 10:03      0-    345  Linus 3.14-rc1

However that happen to be caused by an independent "scheduling while
atomic" bug:

[   20.038125] Fixing recursive fault but reboot is needed!
[   20.038125] BUG: scheduling while atomic: kworker/0:1H/77/0x00000005
[   20.038125] INFO: lockdep is turned off.
[   20.038125] irq event stamp: 758
[   20.038125] hardirqs last  enabled at (757): [<c1c31683>] _raw_spin_unlock_irq+0x22/0x30
[   20.038125] hardirqs last disabled at (758): [<c1c31523>] _raw_spin_lock_irq+0x14/0x73
[   20.038125] softirqs last  enabled at (302): [<c1032d4d>] __do_softirq+0x186/0x1d2
[   20.038125] softirqs last disabled at (295): [<c1002f99>] do_softirq_own_stack+0x2f/0x35
[   20.038125] CPU: 0 PID: 77 Comm: kworker/0:1H Tainted: G      D W    3.14.0-rc1 #1
[   20.038125] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   20.038125]  c0420610 c0420610 c0449a38 c1c1f562 c0449a54 c1c1b59c c1f91661 c0420938
[   20.038125]  0000004d 00000005 c0420610 c0449acc c1c2e4e2 c105fff8 01449a7c 000004af
[   20.038125]  c0420610 0000002c 00000001 c0449a7c c0420610 c0449ab4 c106001c 00000000
[   20.038125] Call Trace:
[   20.038125]  [<c1c1f562>] dump_stack+0x16/0x18
[   20.038125]  [<c1c1b59c>] __schedule_bug+0x5d/0x6f
[   20.038125]  [<c1c2e4e2>] __schedule+0x45/0x55f
[   20.038125]  [<c105fff8>] ? vprintk_emit+0x367/0x3a4
[   20.038125]  [<c106001c>] ? vprintk_emit+0x38b/0x3a4
[   20.038125]  [<c105876b>] ? trace_hardirqs_off+0xb/0xd
[   20.038125]  [<c1c1c185>] ? printk+0x38/0x3a
[   20.038125]  [<c1c2ea59>] schedule+0x5d/0x5f
[   20.038125]  [<c10314b8>] do_exit+0xcc/0x75d
[   20.038125]  [<c1060e7b>] ? kmsg_dump+0x184/0x191
[   20.038125]  [<c1060d13>] ? kmsg_dump+0x1c/0x191
[   20.038125]  [<c1003d54>] oops_end+0x7e/0x83
[   20.038125]  [<c1c1ae82>] no_context+0x1ba/0x1c2
[   20.038125]  [<c1c1afc1>] __bad_area_nosemaphore+0x137/0x13f
[   20.038125]  [<c1c1a82d>] ? pte_offset_kernel+0x13/0x2a
[   20.038125]  [<c1c1aa5f>] ? spurious_fault+0x75/0xd5
[   20.038125]  [<c1c1afdb>] bad_area_nosemaphore+0x12/0x14

Thanks,
Fengguang