Commit b80ef10e authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Ingo Molnar
Browse files

x86: Move do_page_fault()'s error path under unlikely() 



Ingo suggested SIGKILL check should be moved into slowpath
function. This will reduce the page fault fastpath impact
of this recent commit:

  37b23e05: x86,mm: make pagefault killable

Suggested-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: kamezawa.hiroyu@jp.fujitsu.com
Cc: minchan.kim@gmail.com
Cc: willy@linux.intel.com
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/4DDE0B5C.9050907@jp.fujitsu.com


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent de66ee97

arch/x86/mm/fault.c

+20 −15
Original line number Diff line number Diff line
@@ -823,16 +823,30 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, 
	force_sig_info_fault(SIGBUS, code, address, tsk, fault);

}



static noinline void

static noinline int

mm_fault_error(struct pt_regs *regs, unsigned long error_code,

	       unsigned long address, unsigned int fault)

{

	/*

	 * Pagefault was interrupted by SIGKILL. We have no reason to

	 * continue pagefault.

	 */

	if (fatal_signal_pending(current)) {

		if (!(fault & VM_FAULT_RETRY))

			up_read(&current->mm->mmap_sem);

		if (!(error_code & PF_USER))

			no_context(regs, error_code, address);

		return 1;

	}

	if (!(fault & VM_FAULT_ERROR))

		return 0;



	if (fault & VM_FAULT_OOM) {

		/* Kernel mode? Handle exceptions or die: */

		if (!(error_code & PF_USER)) {

			up_read(&current->mm->mmap_sem);

			no_context(regs, error_code, address);

			return;

			return 1;

		}



		out_of_memory(regs, error_code, address);
@@ -843,6 +857,7 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code, 
		else

			BUG();

	}

	return 1;

}



static int spurious_fault_check(unsigned long error_code, pte_t *pte)
@@ -1133,18 +1148,8 @@ good_area: 
	 */

	fault = handle_mm_fault(mm, vma, address, flags);



	if (unlikely(fault & VM_FAULT_ERROR)) {

		mm_fault_error(regs, error_code, address, fault);

		return;

	}



	/*

	 * Pagefault was interrupted by SIGKILL. We have no reason to

	 * continue pagefault.

	 */

	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {

		if (!(error_code & PF_USER))

			no_context(regs, error_code, address);

	if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {

		if (mm_fault_error(regs, error_code, address, fault))

			return;

	}

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