Merge remote-tracking branch 'origin/develop-3.0' into develop-3.0-jb

[firefly-linux-kernel-4.4.55.git] / arch / s390 / mm / fault.c

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index a0f9e730f26aec574eace4abac04c74eed59bf5c..6903d441068eaad2e012d94cb6eeffd32549cda6 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -34,9 +34,8 @@
 #include <asm/asm-offsets.h>
 #include <asm/system.h>
 #include <asm/pgtable.h>
-#include <asm/s390_ext.h>
+#include <asm/irq.h>
 #include <asm/mmu_context.h>
-#include <asm/compat.h>
 #include "../kernel/entry.h"
 
 #ifndef CONFIG_64BIT
@@ -245,9 +244,12 @@ static noinline void do_fault_error(struct pt_regs *regs, long int_code,
                do_no_context(regs, int_code, trans_exc_code);
                break;
        default: /* fault & VM_FAULT_ERROR */
-               if (fault & VM_FAULT_OOM)
-                       pagefault_out_of_memory();
-               else if (fault & VM_FAULT_SIGBUS) {
+               if (fault & VM_FAULT_OOM) {
+                       if (!(regs->psw.mask & PSW_MASK_PSTATE))
+                               do_no_context(regs, int_code, trans_exc_code);
+                       else
+                               pagefault_out_of_memory();
+               } else if (fault & VM_FAULT_SIGBUS) {
                        /* Kernel mode? Handle exceptions or die */
                        if (!(regs->psw.mask & PSW_MASK_PSTATE))
                                do_no_context(regs, int_code, trans_exc_code);
@@ -277,7 +279,8 @@ static inline int do_exception(struct pt_regs *regs, int access,
        struct mm_struct *mm;
        struct vm_area_struct *vma;
        unsigned long address;
-       int fault, write;
+       unsigned int flags;
+       int fault;
 
        if (notify_page_fault(regs))
                return 0;
@@ -296,6 +299,10 @@ static inline int do_exception(struct pt_regs *regs, int access,
 
        address = trans_exc_code & __FAIL_ADDR_MASK;
        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
+       flags = FAULT_FLAG_ALLOW_RETRY;
+       if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
+               flags |= FAULT_FLAG_WRITE;
+retry:
        down_read(&mm->mmap_sem);
 
        fault = VM_FAULT_BADMAP;
@@ -325,21 +332,31 @@ static inline int do_exception(struct pt_regs *regs, int access,
         * make sure we exit gracefully rather than endlessly redo
         * the fault.
         */
-       write = (access == VM_WRITE ||
-                (trans_exc_code & store_indication) == 0x400) ?
-               FAULT_FLAG_WRITE : 0;
-       fault = handle_mm_fault(mm, vma, address, write);
+       fault = handle_mm_fault(mm, vma, address, flags);
        if (unlikely(fault & VM_FAULT_ERROR))
                goto out_up;
 
-       if (fault & VM_FAULT_MAJOR) {
-               tsk->maj_flt++;
-               perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
-                                    regs, address);
-       } else {
-               tsk->min_flt++;
-               perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
-                                    regs, address);
+       /*
+        * Major/minor page fault accounting is only done on the
+        * initial attempt. If we go through a retry, it is extremely
+        * likely that the page will be found in page cache at that point.
+        */
+       if (flags & FAULT_FLAG_ALLOW_RETRY) {
+               if (fault & VM_FAULT_MAJOR) {
+                       tsk->maj_flt++;
+                       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
+                                     regs, address);
+               } else {
+                       tsk->min_flt++;
+                       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
+                                     regs, address);
+               }
+               if (fault & VM_FAULT_RETRY) {
+                       /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+                        * of starvation. */
+                       flags &= ~FAULT_FLAG_ALLOW_RETRY;
+                       goto retry;
+               }
        }
        /*
         * The instruction that caused the program check will
@@ -429,10 +446,9 @@ int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
        access = write ? VM_WRITE : VM_READ;
        fault = do_exception(&regs, access, uaddr | 2);
        if (unlikely(fault)) {
-               if (fault & VM_FAULT_OOM) {
-                       pagefault_out_of_memory();
-                       fault = 0;
-               } else if (fault & VM_FAULT_SIGBUS)
+               if (fault & VM_FAULT_OOM)
+                       return -EFAULT;
+               else if (fault & VM_FAULT_SIGBUS)
                        do_sigbus(&regs, pgm_int_code, uaddr);
        }
        return fault ? -EFAULT : 0;
@@ -485,7 +501,6 @@ int pfault_init(void)
                "2:\n"
                EX_TABLE(0b,1b)
                : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
-        __ctl_set_bit(0, 9);
         return rc;
 }
 
@@ -500,7 +515,6 @@ void pfault_fini(void)
 
        if (!MACHINE_IS_VM || pfault_disable)
                return;
-       __ctl_clear_bit(0,9);
        asm volatile(
                "       diag    %0,0,0x258\n"
                "0:\n"
@@ -553,6 +567,7 @@ 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
@@ -562,14 +577,22 @@ 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);
@@ -594,6 +617,7 @@ 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;
@@ -615,6 +639,7 @@ static int __init pfault_irq_init(void)
        rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
        if (rc)
                goto out_pfault;
+       service_subclass_irq_register();
        hotcpu_notifier(pfault_cpu_notify, 0);
        return 0;