x86: mm: move mmap_sem unlock from mm_fault_error() to caller

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 <torvalds@linux-foundation.org>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 6d0e5472a5e508e11b39819a136b8568e81ea61c..dbd4abf667002465078fe5c7f086d405300738be 100644 (file)
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -841,11 +841,8 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
          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);
@@ -876,7 +873,6 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
               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;
        }
@@ -884,14 +880,11 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
        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
@@ -1227,6 +1220,7 @@ good_area:
                return;
 
        if (unlikely(fault & VM_FAULT_ERROR)) {
+               up_read(&mm->mmap_sem);
                mm_fault_error(regs, error_code, address, fault);
                return;
        }