[PATCH 3/3] powerpc/mm: move mmap_sem unlocking in do_page_fault()

[Laurent Dufour]

Since the fault retry is now handled earlier, we can release the
mmap_sem lock earlier too and remove later unlocking previously done in
mm_fault_error().

Signed-off-by: Laurent Dufour <lduf...@linux.vnet.ibm.com>
---
 arch/powerpc/mm/fault.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 2a6bc7e6e69a..21e06cce8984 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -151,13 +151,6 @@ static int mm_fault_error(struct pt_regs *regs, unsigned 
long addr, int fault)
         * continue the pagefault.
         */
        if (fatal_signal_pending(current)) {
-               /*
-                * If we have retry set, the mmap semaphore will have
-                * alrady been released in __lock_page_or_retry(). Else
-                * we release it now.
-                */
-               if (!(fault & VM_FAULT_RETRY))
-                       up_read(&current->mm->mmap_sem);
                /* Coming from kernel, we need to deal with uaccess fixups */
                if (user_mode(regs))
                        return MM_FAULT_RETURN;
@@ -170,8 +163,6 @@ static int mm_fault_error(struct pt_regs *regs, unsigned 
long addr, int fault)
 
        /* Out of memory */
        if (fault & VM_FAULT_OOM) {
-               up_read(&current->mm->mmap_sem);
-
                /*
                 * We ran out of memory, or some other thing happened to us that
                 * made us unable to handle the page fault gracefully.
@@ -182,10 +173,8 @@ static int mm_fault_error(struct pt_regs *regs, unsigned 
long addr, int fault)
                return MM_FAULT_RETURN;
        }
 
-       if (fault & 
(VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
-               up_read(&current->mm->mmap_sem);
+       if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE))
                return do_sigbus(regs, addr, fault);
-       }
 
        /* We don't understand the fault code, this is fatal */
        BUG();
@@ -452,11 +441,12 @@ int do_page_fault(struct pt_regs *regs, unsigned long 
address,
                                goto retry;
                }
                /* We will enter mm_fault_error() below */
-       }
+       } else
+               up_read(&current->mm->mmap_sem);
 
        if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
                if (fault & VM_FAULT_SIGSEGV)
-                       goto bad_area;
+                       goto bad_area_nosemaphore;
                rc = mm_fault_error(regs, address, fault);
                if (rc >= MM_FAULT_RETURN)
                        goto bail;
@@ -488,7 +478,6 @@ int do_page_fault(struct pt_regs *regs, unsigned long 
address,
                              regs, address);
        }
 
-       up_read(&mm->mmap_sem);
        goto bail;
 
 bad_area:
-- 
2.7.4