Fix oops from i386-make-compat_vdso-runtime-selectable.patch.
Even mingetty at system startup finds it easy to trigger an oops
while reading /proc/PID/maps: though it has a good hold on the mm
itself, that cannot stop exit_mm() from resetting tsk->mm to NULL.
(It is usually show_map()'s call to get_gate_vma() which oopses,
and I expect we could change that to check priv->tail_vma instead;
but no matter, even m_start()'s call just after get_task_mm() is racy.)
Signed-off-by: Hugh Dickins <[EMAIL PROTECTED]>
--- 2.6.21-rc6-mm1/arch/i386/kernel/sysenter.c 2007-04-10 11:37:23.000000000
+0100
+++ linux/arch/i386/kernel/sysenter.c 2007-04-13 16:43:45.000000000 +0100
@@ -326,8 +326,10 @@ const char *arch_vma_name(struct vm_area
struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
+ struct mm_struct *mm = tsk->mm;
+
/* Check to see if this task was created in compat vdso mode */
- if (tsk->mm->context.vdso == (void *)VDSO_HIGH_BASE)
+ if (mm && mm->context.vdso == (void *)VDSO_HIGH_BASE)
return &gate_vma;
return NULL;
}
-
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