x86: add unlikely() to fatal signal check

PATCH In review KOSAKI Motohiro 1 participant 2 messages May 26, 2011

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KOSAKI Motohiro

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2011-05-26 08:12 UTC #0 lore raw

PATCH 1/1 x86: add unlikely() to fatal signal check

Ingo suggested SIGKILL check should be moved into slowpath function. It may reduce page fault fastpath impact. This patch do that.

Signed-off-by KOSAKI Motohiro <[email protected]>

---
 arch/x86/mm/fault.c |   35 ++++++++++++++++++++---------------
 1 files changed, 20 insertions(+), 15 deletions(-)

arch/x86/mm/fault.c +20 ~~-15~~

index f7a2a05..2dbf6bf 100644
@@ -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)

@@ -1133,19 +1148,9 @@ 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);
-		return;
+	if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
+		if (mm_fault_error(regs, error_code, address, fault))
+			return;
 	}
 
 	/*

Signature · 1 line

1.7.3.1

tip-bot for KOSAKI Motohiro

author

2011-05-26 12:02 UTC #1 lore raw

[tip:x86/urgent] x86: Move do_page_fault()'s error path under unlikely()

Commit-ID:  b80ef10e84d85a06bcd0b3a24a752ec32d0e0e40
Gitweb:     http://git.kernel.org/tip/b80ef10e84d85a06bcd0b3a24a752ec32d0e0e40
Author:     KOSAKI Motohiro <[email protected]>
AuthorDate: Thu, 26 May 2011 17:12:12 +0900
Committer:  Ingo Molnar <[email protected]>
CommitDate: Thu, 26 May 2011 13:54:03 +0200

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:

37b23e0525d3: x86,mm: make pagefault killable

Signed-off-by KOSAKI Motohiro <[email protected]>

Cc [email protected]

Cc Andrew Morton <[email protected]>

Cc Linus Torvalds <[email protected]>

Link http://lkml.kernel.org/r/[email protected] open here

Signed-off-by Ingo Molnar <[email protected]>

---
 arch/x86/mm/fault.c |   35 ++++++++++++++++++++---------------
 1 files changed, 20 insertions(+), 15 deletions(-)

arch/x86/mm/fault.c +20 ~~-15~~

index f7a2a05..2dbf6bf 100644
@@ -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)

@@ -1133,19 +1148,9 @@ 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);
-		return;
+	if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
+		if (mm_fault_error(regs, error_code, address, fault))
+			return;
 	}
 
 	/*