[PATCH 3.14 39/42] x86: mm: move mmap_sem unlock from mm_fault_error() to caller

From: Greg Kroah-Hartman
Date: Sun Apr 26 2015 - 10:06:59 EST


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

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

From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
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
@@ -833,11 +833,8 @@ 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);
@@ -868,7 +865,6 @@ 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;
}
@@ -876,14 +872,11 @@ 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
@@ -1218,6 +1211,7 @@ 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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