[gentoo-commits] linux-patches r1756 - genpatches-2.6/trunk/2.6.34

[gentoo-commits] linux-patches r1756 - genpatches-2.6/trunk/2.6.34

[Mike Pagano (mpagano)]

Author: mpagano
Date: 2010-08-20 14:30:36 +0000 (Fri, 20 Aug 2010)
New Revision: 1756

Added:
   genpatches-2.6/trunk/2.6.34/1800_page-table-unmap-for-stack-guard-fix.patch
Modified:
   genpatches-2.6/trunk/2.6.34/0000_README
Log:
Patch to fix page table unmap for stack guard page

Modified: genpatches-2.6/trunk/2.6.34/0000_README
===================================================================
--- genpatches-2.6/trunk/2.6.34/0000_README	2010-08-20 13:17:15 UTC (rev 1755)
+++ genpatches-2.6/trunk/2.6.34/0000_README	2010-08-20 14:30:36 UTC (rev 1756)
@@ -59,6 +59,10 @@
 From:	http://bugs.gentoo.org/show_bug.cgi?id=332949
 Desc:	Add missing include
 
+Patch:  1800_page-table-unmap-for-stack-guard-fix.patch
+From:   https://bugzilla.kernel.org/show_bug.cgi?id=16588
+Desc:   Fix page table unmap for stack guard page properly
+
 Patch:	2600_synaptic-cap-ID-check-fix.patch
 From:	http://bugs.gentoo.org/show_bug.cgi?id=328527
 Desc:	Synaptics capability ID check fix

Added: genpatches-2.6/trunk/2.6.34/1800_page-table-unmap-for-stack-guard-fix.patch
===================================================================
--- genpatches-2.6/trunk/2.6.34/1800_page-table-unmap-for-stack-guard-fix.patch	                        (rev 0)
+++ genpatches-2.6/trunk/2.6.34/1800_page-table-unmap-for-stack-guard-fix.patch	2010-08-20 14:30:36 UTC (rev 1756)
@@ -0,0 +1,76 @@
+From 11ac552477e32835cb6970bf0a70c210807f5673 Mon Sep 17 00:00:00 2001
+From: Linus Torvalds <torvalds@linux-foundation.org>
+Date: Sat, 14 Aug 2010 11:44:56 -0700
+Subject: [PATCH] mm: fix page table unmap for stack guard page properly
+MIME-Version: 1.0
+Content-Type: text/plain; charset=utf8
+Content-Transfer-Encoding: 8bit
+
+We do in fact need to unmap the page table _before_ doing the whole
+stack guard page logic, because if it is needed (mainly 32-bit x86 with
+PAE and CONFIG_HIGHPTE, but other architectures may use it too) then it
+will do a kmap_atomic/kunmap_atomic.
+
+And those kmaps will create an atomic region that we cannot do
+allocations in.  However, the whole stack expand code will need to do
+anon_vma_prepare() and vma_lock_anon_vma() and they cannot do that in an
+atomic region.
+
+Now, a better model might actually be to do the anon_vma_prepare() when
+_creating_ a VM_GROWSDOWN segment, and not have to worry about any of
+this at page fault time.  But in the meantime, this is the
+straightforward fix for the issue.
+
+See https://bugzilla.kernel.org/show_bug.cgi?id=16588 for details.
+
+Reported-by: Wylda <wylda@volny.cz>
+Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
+Reported-by: Mike Pagano <mpagano@gentoo.org>
+Reported-by: François Valenduc <francois.valenduc@tvcablenet.be>
+Tested-by: Ed Tomlinson <edt@aei.ca>
+Cc: Pekka Enberg <penberg@kernel.org>
+Cc: Greg KH <gregkh@suse.de>
+Cc: stable@kernel.org
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+---
+ mm/memory.c |   13 ++++++-------
+ 1 files changed, 6 insertions(+), 7 deletions(-)
+
+diff --git a/mm/memory.c b/mm/memory.c
+index 9b3b73f..b6e5fd2 100644
+--- a/mm/memory.c
++++ b/mm/memory.c
+@@ -2792,24 +2792,23 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
+ 	spinlock_t *ptl;
+ 	pte_t entry;
+ 
+-	if (check_stack_guard_page(vma, address) < 0) {
+-		pte_unmap(page_table);
++	pte_unmap(page_table);
++
++	/* Check if we need to add a guard page to the stack */
++	if (check_stack_guard_page(vma, address) < 0)
+ 		return VM_FAULT_SIGBUS;
+-	}
+ 
++	/* Use the zero-page for reads */
+ 	if (!(flags & FAULT_FLAG_WRITE)) {
+ 		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
+ 						vma->vm_page_prot));
+-		ptl = pte_lockptr(mm, pmd);
+-		spin_lock(ptl);
++		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
+ 		if (!pte_none(*page_table))
+ 			goto unlock;
+ 		goto setpte;
+ 	}
+ 
+ 	/* Allocate our own private page. */
+-	pte_unmap(page_table);
+-
+ 	if (unlikely(anon_vma_prepare(vma)))
+ 		goto oom;
+ 	page = alloc_zeroed_user_highpage_movable(vma, address);
+-- 
+1.7.2.2
+