1 files changed, 39 insertions, 23 deletions

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index a0f9e730f26a..fe103e891e7a 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -34,7 +34,7 @@
 #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"
@@ -245,9 +245,12 @@ 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 +280,8 @@ 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 +300,10 @@ 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 +333,31 @@ 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 +447,9 @@ 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 +502,6 @@ 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 +516,6 @@ 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"
@@ -615,6 +630,7 @@ 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;