[S390] mm: handle kernel caused page fault oom situations
If e.g. copy_from_user() generates a page fault and the kernel runs
into an OOM situation the system might lock up.
If the OOM killer sends a SIG_KILL to the current process it can't
handle it since it is stuck in a copy_from_user() - page fault loop.
Fix this by adding the same fix as other architectures have.
E.g. the x86 variant f86268 "x86/mm: Handle mm_fault_error() in kernel
space"
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 105fa10..b57723a 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -245,9 +245,12 @@
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);
@@ -429,10 +432,9 @@
access = write ? VM_WRITE : VM_READ;
fault = do_exception(®s, 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(®s, pgm_int_code, uaddr);
}
return fault ? -EFAULT : 0;