• Ingo Molnar's avatar
    x86: fix "BUG: sleeping function called from invalid context" in print_vma_addr() · e8bff74a
    Ingo Molnar authored
    Jiri Kosina reported the following deadlock scenario with
    show_unhandled_signals enabled:
    
     [   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]
    
    and tracked it down to:
    
      commit 03252919
      Author: Andi Kleen <ak@suse.de>
      Date:   Wed Jan 30 13:33:18 2008 +0100
    
          x86: print which shared library/executable faulted in segfault etc. messages
    
    the problem is that we call down_read() from an atomic context.
    
    Solve this by returning from print_vma_addr() if the preempt count is
    elevated. Update preempt_conditional_sti / preempt_conditional_cli to
    unconditionally lift the preempt count even on !CONFIG_PREEMPT.
    Reported-by: default avatarJiri Kosina <jkosina@suse.cz>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    e8bff74a
memory.c 72.9 KB