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[RFC v4 18/20] x86/mm: Update the handle_speculative_fault's path

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  [RFC v4 18/20] x86/mm: Update the handle_speculative_fault's path Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-06-09 16:30 +0200

#1662499 — [RFC v4 18/20] x86/mm: Update the handle_speculative_fault's path

If handle_speculative_fault failed due to a VM ERROR, we try again the
slow path to allow the signal to be delivered.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
 arch/x86/mm/fault.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 0c0b45dfda76..02c0b884ca18 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1369,10 +1369,14 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
 		fault = handle_speculative_fault(mm, address,
 					flags & ~FAULT_FLAG_ALLOW_RETRY);
 
-		if (fault & VM_FAULT_RETRY)
-			goto retry;
-
-		goto done;
+		/*
+		 * We also check against VM_FAULT_ERROR because we have to
+		 * raise a signal by calling later mm_fault_error() which
+		 * requires the vma pointer to be set. So in that case,
+		 * we fall through the normal path.
+		 */
+		if (!(fault & VM_FAULT_RETRY || fault & VM_FAULT_ERROR))
+			goto done;
 	}
 
 	/*
@@ -1478,20 +1482,13 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
 		return;
 	}
 
-	if (unlikely(fault & VM_FAULT_RETRY)) {
-		if (fatal_signal_pending(current))
-			return;
-
-		goto done;
-	}
-
 	up_read(&mm->mmap_sem);
-done:
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		mm_fault_error(regs, error_code, address, vma, fault);
 		return;
 	}
 
+done:
 	/*
 	 * Major/minor page fault accounting. If any of the events
 	 * returned VM_FAULT_MAJOR, we account it as a major fault.
-- 
2.7.4

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