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To: LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
From: Larry Finger <Larry.Finger@lwfinger.net>
Subject: Sleeping BUG in khugepaged for i586
Message-ID: <968ae9a9-5345-18ca-c7ce-d9beaf9f43b6@lwfinger.net>
Date: Sat, 3 Jun 2017 14:24:26 -0500
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I recently turned on locking diagnostics for a Dell Latitude D600 laptop, which 
requires a 32-bit kernel. In the log I found the following:

BUG: sleeping function called from invalid context at mm/khugepaged.c:655
in_atomic(): 1, irqs_disabled(): 0, pid: 20, name: khugepaged
1 lock held by khugepaged/20:
  #0:  (&mm->mmap_sem){++++++}, at: [<c03d6609>] 
collapse_huge_page.isra.47+0x439/0x1240
CPU: 0 PID: 20 Comm: khugepaged Tainted: G        W 
4.12.0-rc1-wl-12125-g952a068 #80
Hardware name: Dell Computer Corporation Latitude D600 
/03U652, BIOS A05 05/29/2003
Call Trace:
  dump_stack+0x76/0xb2
  ___might_sleep+0x174/0x230
  collapse_huge_page.isra.47+0xacf/0x1240
  khugepaged_scan_mm_slot+0x41e/0xc00
  ? _raw_spin_lock+0x46/0x50
  khugepaged+0x277/0x4f0
  ? prepare_to_wait_event+0xe0/0xe0
  kthread+0xeb/0x120
  ? khugepaged_scan_mm_slot+0xc00/0xc00
  ? kthread_create_on_node+0x30/0x30
  ret_from_fork+0x21/0x30

I have no idea when this problem was introduced. Of course, I will test any 
proposed fixes.

Thanks,

Larry