[PATCH 3.10 30/31] x86: mm: move mmap_sem unlock from mm_fault_error() to caller

[Greg Kroah-Hartman]

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Torvalds <torva...@linux-foundation.org>

commit 7fb08eca45270d0ae86e1ad9d39c40b7a55d0190 upstream.

This replaces four copies in various stages of mm_fault_error() handling
with just a single one.  It will also allow for more natural placement
of the unlocking after some further cleanup.

Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/x86/mm/fault.c |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -812,11 +812,8 @@ do_sigbus(struct pt_regs *regs, unsigned
          unsigned int fault)
 {
        struct task_struct *tsk = current;
-       struct mm_struct *mm = tsk->mm;
        int code = BUS_ADRERR;
 
-       up_read(&mm->mmap_sem);
-
        /* Kernel mode? Handle exceptions or die: */
        if (!(error_code & PF_USER)) {
                no_context(regs, error_code, address, SIGBUS, BUS_ADRERR);
@@ -847,7 +844,6 @@ mm_fault_error(struct pt_regs *regs, uns
               unsigned long address, unsigned int fault)
 {
        if (fatal_signal_pending(current) && !(error_code & PF_USER)) {
-               up_read(&current->mm->mmap_sem);
                no_context(regs, error_code, address, 0, 0);
                return;
        }
@@ -855,14 +851,11 @@ mm_fault_error(struct pt_regs *regs, uns
        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,
                                   SIGSEGV, SEGV_MAPERR);
                        return;
                }
 
-               up_read(&current->mm->mmap_sem);
-
                /*
                 * We ran out of memory, call the OOM killer, and return the
                 * userspace (which will retry the fault, or kill us if we got
@@ -1195,6 +1188,7 @@ good_area:
                return;
 
        if (unlikely(fault & VM_FAULT_ERROR)) {
+               up_read(&mm->mmap_sem);
                mm_fault_error(regs, error_code, address, fault);
                return;
        }


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