2 files changed, 29 insertions, 8 deletions

diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c
index 4d93dff6b371..3d15243ce692 100644
--- a/arch/um/kernel/reboot.c
+++ b/arch/um/kernel/reboot.c
@@ -4,7 +4,9 @@
  */
 
 #include "linux/sched.h"
+#include "linux/spinlock.h"
 #include "linux/slab.h"
+#include "linux/oom.h"
 #include "kern_util.h"
 #include "os.h"
 #include "skas.h"
@@ -22,13 +24,18 @@ static void kill_off_processes(void)
                 struct task_struct *p;
                 int pid;
 
+                read_lock(&tasklist_lock);
                 for_each_process(p) {
-                        if (p->mm == NULL)
-                                continue;
+                        struct task_struct *t;
 
-                        pid = p->mm->context.id.u.pid;
+                        t = find_lock_task_mm(p);
+                        if (!t)
+                                continue;
+                        pid = t->mm->context.id.u.pid;
+                        task_unlock(t);
                         os_kill_ptraced_process(pid, 1);
                 }
+                read_unlock(&tasklist_lock);
         }
 }
 
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index dafc94715950..3be60765c0e2 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -30,6 +30,8 @@ int handle_page_fault(unsigned long address, unsigned long ip,
         pmd_t *pmd;
         pte_t *pte;
         int err = -EFAULT;
+        unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+                                 (is_write ? FAULT_FLAG_WRITE : 0);
 
         *code_out = SEGV_MAPERR;
 
@@ -40,6 +42,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
         if (in_atomic())
                 goto out_nosemaphore;
 
+retry:
         down_read(&mm->mmap_sem);
         vma = find_vma(mm, address);
         if (!vma)
@@ -65,7 +68,11 @@ good_area:
         do {
                 int fault;
 
-                fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
+                fault = handle_mm_fault(mm, vma, address, flags);
+
+                if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+                        goto out_nosemaphore;
+
                 if (unlikely(fault & VM_FAULT_ERROR)) {
                         if (fault & VM_FAULT_OOM) {
                                 goto out_of_memory;
@@ -75,10 +82,17 @@ good_area:
                         }
                         BUG();
                 }
-                if (fault & VM_FAULT_MAJOR)
-                        current->maj_flt++;
-                else
-                        current->min_flt++;
+                if (flags & FAULT_FLAG_ALLOW_RETRY) {
+                        if (fault & VM_FAULT_MAJOR)
+                                current->maj_flt++;
+                        else
+                                current->min_flt++;
+                        if (fault & VM_FAULT_RETRY) {
+                                flags &= ~FAULT_FLAG_ALLOW_RETRY;
+
+                                goto retry;
+                        }
+                }
 
                 pgd = pgd_offset(mm, address);
                 pud = pud_offset(pgd, address);