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| author | Thomas Gleixner <tglx@linutronix.de> | 2009-01-13 23:36:34 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-02-20 14:40:21 -0800 |
| commit | 14da78c411a1218764439c0004f0ea2b7d0c0c4c (patch) | |
| tree | 0b7c9c3db8632da8ac04f0a79f1ea62127d0364c | |
| parent | df94b12439ca449a852e579fc2952dac80f70c90 (diff) | |
| download | lwn-14da78c411a1218764439c0004f0ea2b7d0c0c4c.tar.gz lwn-14da78c411a1218764439c0004f0ea2b7d0c0c4c.zip | |
x86, vm86: fix preemption bug
commit be716615fe596ee117292dc615e95f707fb67fd1 upstream.
Commit 3d2a71a596bd9c761c8487a2178e95f8a61da083 ("x86, traps: converge
do_debug handlers") changed the preemption disable logic of do_debug()
so vm86_handle_trap() is called with preemption disabled resulting in:
BUG: sleeping function called from invalid context at include/linux/kernel.h:155
in_atomic(): 1, irqs_disabled(): 0, pid: 3005, name: dosemu.bin
Pid: 3005, comm: dosemu.bin Tainted: G W 2.6.29-rc1 #51
Call Trace:
[<c050d669>] copy_to_user+0x33/0x108
[<c04181f4>] save_v86_state+0x65/0x149
[<c0418531>] handle_vm86_trap+0x20/0x8f
[<c064e345>] do_debug+0x15b/0x1a4
[<c064df1f>] debug_stack_correct+0x27/0x2c
[<c040365b>] sysenter_do_call+0x12/0x2f
BUG: scheduling while atomic: dosemu.bin/3005/0x10000001
Restore the original calling convention and reenable preemption before
calling handle_vm86_trap().
Reported-by: Michal Suchanek <hramrach@centrum.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | arch/x86/kernel/traps.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 04d242ab0161..662f1b43e43d 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -104,6 +104,12 @@ static inline void preempt_conditional_sti(struct pt_regs *regs) local_irq_enable(); } +static inline void conditional_cli(struct pt_regs *regs) +{ + if (regs->flags & X86_EFLAGS_IF) + local_irq_disable(); +} + static inline void preempt_conditional_cli(struct pt_regs *regs) { if (regs->flags & X86_EFLAGS_IF) @@ -629,8 +635,10 @@ clear_dr7: #ifdef CONFIG_X86_32 debug_vm86: + /* reenable preemption: handle_vm86_trap() might sleep */ + dec_preempt_count(); handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1); - preempt_conditional_cli(regs); + conditional_cli(regs); return; #endif |