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