Patch "x86: mm: move mmap_sem unlock from mm_fault_error() to caller" has been added to the 3.14-stable tree

Patch "x86: mm: move mmap_sem unlock from mm_fault_error() to caller" has been added to the 3.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 3.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-mm-move-mmap_sem-unlock-from-mm_fault_error-to-caller.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 7fb08eca45270d0ae86e1ad9d39c40b7a55d0190 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 15 Dec 2014 14:46:06 -0800
Subject: x86: mm: move mmap_sem unlock from mm_fault_error() to caller

From: Linus Torvalds <torvalds@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 <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@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
@@ -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;
 	}


Patches currently in stable-queue which might be from torvalds@linux-foundation.org are

queue-3.14/vm-make-stack-guard-page-errors-return-vm_fault_sigsegv-rather-than-sigbus.patch
queue-3.14/x86-mm-move-mmap_sem-unlock-from-mm_fault_error-to-caller.patch
queue-3.14/mm-hwpoison-drop-lru_add_drain_all-in-__soft_offline_page.patch
queue-3.14/vm-add-vm_fault_sigsegv-handling-support.patch