Patch "Allow stack to grow up to address space limit" has been added to the 4.9-stable tree

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

Allow stack to grow up to address space limit

to the 4.9-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:
allow-stack-to-grow-up-to-address-space-limit.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Helge Deller <[email protected]>
Date: Mon, 19 Jun 2017 17:34:05 +0200
Subject: Allow stack to grow up to address space limit

From: Helge Deller <[email protected]>

commit bd726c90b6b8ce87602208701b208a208e6d5600 upstream.

Fix expand_upwards() on architectures with an upward-growing stack (parisc, metag and partly IA-64) to allow the stack to reliably grow exactly up to the address space limit given by TASK_SIZE.

---
 mm/mmap.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

@@ -2224,16 +2224,19 @@ int expand_upwards(struct vm_area_struct
 	if (!(vma->vm_flags & VM_GROWSUP))
 		return -EFAULT;
 
-	/* Guard against wrapping around to address 0. */
+	/* Guard against exceeding limits of the address space. */
 	address &= PAGE_MASK;
-	address += PAGE_SIZE;
-	if (!address)
+	if (address >= TASK_SIZE)
 		return -ENOMEM;
+	address += PAGE_SIZE;
 
 	/* Enforce stack_guard_gap */
 	gap_addr = address + stack_guard_gap;
-	if (gap_addr < address)
-		return -ENOMEM;
+
+	/* Guard against overflow */
+	if (gap_addr < address || gap_addr > TASK_SIZE)
+		gap_addr = TASK_SIZE;
+
 	next = vma->vm_next;
 	if (next && next->vm_start < gap_addr) {
 		if (!(next->vm_flags & VM_GROWSUP))

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/allow-stack-to-grow-up-to-address-space-limit.patch queue-4.9/mm-larger-stack-guard-gap-between-vmas.patch