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Commit 99583181 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

[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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent b3966378

arch/s390/mm/fault.c

+9 −7
Original line number Diff line number Diff line
@@ -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)

		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) {

		} 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 @@ 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;