Bug 434760

Summary: F-9 pv_ops: recursive locking warning during x86_32 DomU boot
Product: [Fedora] Fedora Reporter: Mark McLoughlin <markmc>
Component: kernel-xen-2.6Assignee: Xen Maintainance List <xen-maint>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: low Docs Contact:
Priority: low    
Version: rawhideCC: berrange, ehabkost, orion
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2008-03-25 13:28:12 EDT Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Bug Depends On:    
Bug Blocks: 434756    

Description Mark McLoughlin 2008-02-25 05:54:06 EST
Seeing this with kernel-xen-2.6.24-23.7.pv_ops during DomU boot:

Red Hat nash version 6.0.29 starting
Mounting proc filesystem
Mounting sysfs filesystem
Creating /dev
Creating initial device nodes
Setting up hotplug.

=============================================
[ INFO: possible recursive locking detected ]
2.6.24-23.7.pv_ops.fc9xen #1
---------------------------------------------
init/1 is trying to acquire lock:
 (__pte_lockptr(new)){--..}, at: [<c10047c4>] pin_page+0x6c/0x12d

but task is already holding lock:
 (__pte_lockptr(new)){--..}, at: [<c10047c4>] pin_page+0x6c/0x12d

other info that might help us debug this:
4 locks held by init/1:
 #0:  (&mm->mmap_sem){----}, at: [<c10336c7>] copy_process+0xa7f/0x1306
 #1:  (&mm->mmap_sem/1){--..}, at: [<c10336dd>] copy_process+0xa95/0x1306
 #2:  (&mm->page_table_lock){--..}, at: [<c1004998>] xen_dup_mmap+0x11/0x24
 #3:  (__pte_lockptr(new)){--..}, at: [<c10047c4>] pin_page+0x6c/0x12d

stack backtrace:
Pid: 1, comm: init Not tainted 2.6.24-23.7.pv_ops.fc9xen #1
 [<c100bb70>] show_trace+0x1a/0x32
 [<c1255813>] _etext+0x6c/0x72
 [<c105290f>] __lock_acquire+0x8fe/0xc5b
 [<c1052ce7>] lock_acquire+0x7b/0x9e
 [<c12518a6>] _spin_lock+0x2e/0x58
 [<c10047c4>] pin_page+0x6c/0x12d
 [<c1003a94>] pgd_walk+0x119/0x162
 [<c10048c7>] xen_pgd_pin+0x42/0x102
 [<c10049a0>] xen_dup_mmap+0x19/0x24
 [<c10338af>] copy_process+0xc67/0x1306
 [<c1033f77>] do_fork+0x29/0x19e
 [<c100778b>] sys_clone+0x2f/0x31
 [<c100917a>] syscall_call+0x7/0xb
 =======================
Creating block device nodes.
Loading ehci-hcd module
Comment 1 Mark McLoughlin 2008-03-25 04:21:56 EDT
*** Bug 438707 has been marked as a duplicate of this bug. ***
Comment 2 Mark McLoughlin 2008-03-25 12:01:11 EDT
Note, this is only visible on x86_32
Comment 3 Mark McLoughlin 2008-03-25 13:28:12 EDT
Seems this is a harmless warning:

  http://lkml.org/lkml/2008/3/20/273

Hopefully upstream will figure out a way to avoid the warning, but there's no
point in keeping this bug open to track the issue.