print_vma_addr possible deadlock (was Re: Jeste jeden bug)

[Jiri Kosina]

[ sorry for forgetting to change subject properly :) ]

On Wed, 13 Feb 2008, Jiri Kosina wrote:

> [ the original mail was sent by Zdenek to me offlist ]
> 
> On Wed, 13 Feb 2008, Zdenek Kabelac wrote:
> 
> > [   68.379022] gnome-settings-[2941] trap int3 ip:3d2c840f34
> > sp:7fff36f5d100 error:0<3>BUG: sleeping function called from invalid
> > context at kernel/rwsem.c:21
> > [   68.379039] in_atomic():1, irqs_disabled():0
> > [   68.379044] no locks held by gnome-settings-/2941.
> > [   68.379050] Pid: 2941, comm: gnome-settings- Not tainted 2.6.25-rc1 #30
> > [   68.379054]
> > [   68.379056] Call Trace:
> > [   68.379061]  <#DB>  [<ffffffff81064883>] ? __debug_show_held_locks+0x13/0x30
> > [   68.379109]  [<ffffffff81036765>] __might_sleep+0xe5/0x110
> > [   68.379123]  [<ffffffff812f2240>] down_read+0x20/0x70
> > [   68.379137]  [<ffffffff8109cdca>] print_vma_addr+0x3a/0x110
> > [   68.379152]  [<ffffffff8100f435>] do_trap+0xf5/0x170
> > [   68.379168]  [<ffffffff8100f52b>] do_int3+0x7b/0xe0
> > [   68.379180]  [<ffffffff812f4a6f>] int3+0x9f/0xd0
> > [   68.379203]  <<EOE>>
> > [   68.379229]  in libglib-2.0.so.0.1505.0[3d2c800000+dc000]
> 
> Andi,
> 
> in commit 03252919 you introduced print_vma_addr(), but this funcion for 
> obvious reasons takes mmap_sem, so it is not safe to call it from atomic 
> context (i.e. do_trap(), for example), which is behavior your patch 
> introduced.
> 
> 
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