Merge branch 'stable-3.2' into pandora-3.2

[pandora-kernel.git] / arch / s390 / mm / fault.c

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index a9a3018..0fc0a7e 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -36,7 +36,6 @@
 #include <asm/pgtable.h>
 #include <asm/irq.h>
 #include <asm/mmu_context.h>
-#include <asm/compat.h>
 #include "../kernel/entry.h"
 
 #ifndef CONFIG_64BIT
@@ -454,6 +453,7 @@ int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
        struct pt_regs regs;
        int access, fault;
 
+       /* Emulate a uaccess fault from kernel mode. */
        regs.psw.mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_MCHECK;
        if (!irqs_disabled())
                regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
@@ -462,12 +462,12 @@ int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
        uaddr &= PAGE_MASK;
        access = write ? VM_WRITE : VM_READ;
        fault = do_exception(&regs, access, uaddr | 2);
-       if (unlikely(fault)) {
-               if (fault & VM_FAULT_OOM)
-                       return -EFAULT;
-               else if (fault & VM_FAULT_SIGBUS)
-                       do_sigbus(&regs, pgm_int_code, uaddr);
-       }
+       /*
+        * Since the fault happened in kernel mode while performing a uaccess
+        * all we need to do now is emulating a fixup in case "fault" is not
+        * zero.
+        * For the calling uaccess functions this results always in -EFAULT.
+        */
        return fault ? -EFAULT : 0;
 }
 
@@ -584,6 +584,7 @@ static void pfault_interrupt(unsigned int ext_int_code,
                        tsk->thread.pfault_wait = 0;
                        list_del(&tsk->thread.list);
                        wake_up_process(tsk);
+                       put_task_struct(tsk);
                } else {
                        /* Completion interrupt was faster than initial
                         * interrupt. Set pfault_wait to -1 so the initial
@@ -598,14 +599,22 @@ static void pfault_interrupt(unsigned int ext_int_code,
                put_task_struct(tsk);
        } else {
                /* signal bit not set -> a real page is missing. */
-               if (tsk->thread.pfault_wait == -1) {
+               if (tsk->thread.pfault_wait == 1) {
+                       /* Already on the list with a reference: put to sleep */
+                       set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+                       set_tsk_need_resched(tsk);
+               } else if (tsk->thread.pfault_wait == -1) {
                        /* Completion interrupt was faster than the initial
                         * interrupt (pfault_wait == -1). Set pfault_wait
                         * back to zero and exit. */
                        tsk->thread.pfault_wait = 0;
                } else {
                        /* Initial interrupt arrived before completion
-                        * interrupt. Let the task sleep. */
+                        * interrupt. Let the task sleep.
+                        * An extra task reference is needed since a different
+                        * cpu may set the task state to TASK_RUNNING again
+                        * before the scheduler is reached. */
+                       get_task_struct(tsk);
                        tsk->thread.pfault_wait = 1;
                        list_add(&tsk->thread.list, &pfault_list);
                        set_task_state(tsk, TASK_UNINTERRUPTIBLE);
@@ -630,6 +639,7 @@ static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
                        list_del(&thread->list);
                        tsk = container_of(thread, struct task_struct, thread);
                        wake_up_process(tsk);
+                       put_task_struct(tsk);
                }
                spin_unlock_irq(&pfault_lock);
                break;