Fix fallout from the stack guard page fixes.

(mm-fix-page-table-unmap-for-stack-guard-page-properly.patch,
 mm-fix-up-some-user-visible-effects-of-the-stack-guard-page.patch)

3 files changed, 168 insertions, 1 deletions

diff --git a/kernel.spec b/kernel.spec
index e90e10f..8319314 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -47,7 +47,7 @@ Summary: The Linux kernel
 # reset this by hand to 1 (or to 0 and then use rpmdev-bumpspec).
 # scripts/rebase.sh should be made to do that for you, actually.
 #
-%global baserelease 161
+%global baserelease 162
 %global fedora_build %{baserelease}
 
 # base_sublevel is the kernel version we're starting with and patching
@@ -843,6 +843,8 @@ Patch14130: kvm-mmu-fix-conflict-access-permissions-in-direct-sp.patch
 Patch14140: hid-01-usbhid-initialize-interface-pointers-early-enough.patch
 Patch14141: hid-02-fix-suspend-crash-by-moving-initializations-earlier.patch
 
+Patch14150: mm-fix-page-table-unmap-for-stack-guard-page-properly.patch
+Patch14150: mm-fix-up-some-user-visible-effects-of-the-stack-guard-page.patch
 # ==============================================================================
 %endif
 
@@ -1556,6 +1558,10 @@ ApplyPatch kvm-mmu-fix-conflict-access-permissions-in-direct-sp.patch
 ApplyPatch hid-01-usbhid-initialize-interface-pointers-early-enough.patch
 ApplyPatch hid-02-fix-suspend-crash-by-moving-initializations-earlier.patch
 
+# Fix fallout from stack guard page
+ApplyPatch mm-fix-page-table-unmap-for-stack-guard-page-properly.patch
+ApplyPatch mm-fix-up-some-user-visible-effects-of-the-stack-guard-page.patch
+
 # END OF PATCH APPLICATIONS ====================================================
 %endif
 
@@ -2206,6 +2212,11 @@ fi
 %kernel_variant_files -k vmlinux %{with_kdump} kdump
 
 %changelog
+* Tue Aug 17 2010 Chuck Ebbert <cebbert@redhat.com>  2.6.32.19-162
+- Fix fallout from the stack guard page fixes.
+  (mm-fix-page-table-unmap-for-stack-guard-page-properly.patch,
+   mm-fix-up-some-user-visible-effects-of-the-stack-guard-page.patch)
+
 * Sat Aug 14 2010 Chuck Ebbert <cebbert@redhat.com>  2.6.32.19-161
 - Linux 2.6.32.19
 
diff --git a/mm-fix-page-table-unmap-for-stack-guard-page-properly.patch b/mm-fix-page-table-unmap-for-stack-guard-page-properly.patch
new file mode 100644
index 0000000..0989fe3
--- /dev/null
+++ b/mm-fix-page-table-unmap-for-stack-guard-page-properly.patch
@@ -0,0 +1,71 @@
+From: Linus Torvalds <torvalds@linux-foundation.org>
+Date: Sat, 14 Aug 2010 18:44:56 +0000 (-0700)
+Subject: mm: fix page table unmap for stack guard page properly
+X-Git-Tag: v2.6.36-rc1~20
+X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=11ac552477e32835cb6970bf0a70c210807f5673
+
+mm: fix page table unmap for stack guard page properly
+
+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>
+---
+
+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);
diff --git a/mm-fix-up-some-user-visible-effects-of-the-stack-guard-page.patch b/mm-fix-up-some-user-visible-effects-of-the-stack-guard-page.patch
new file mode 100644
index 0000000..095a933
--- /dev/null
+++ b/mm-fix-up-some-user-visible-effects-of-the-stack-guard-page.patch
@@ -0,0 +1,85 @@
+From: Linus Torvalds <torvalds@linux-foundation.org>
+Date: Sun, 15 Aug 2010 18:35:52 +0000 (-0700)
+Subject: mm: fix up some user-visible effects of the stack guard page
+X-Git-Tag: v2.6.36-rc1~5
+X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=d7824370e26325c881b665350ce64fb0a4fde24a
+
+mm: fix up some user-visible effects of the stack guard page
+
+This commit makes the stack guard page somewhat less visible to user
+space. It does this by:
+
+ - not showing the guard page in /proc/<pid>/maps
+
+   It looks like lvm-tools will actually read /proc/self/maps to figure
+   out where all its mappings are, and effectively do a specialized
+   "mlockall()" in user space.  By not showing the guard page as part of
+   the mapping (by just adding PAGE_SIZE to the start for grows-up
+   pages), lvm-tools ends up not being aware of it.
+
+ - by also teaching the _real_ mlock() functionality not to try to lock
+   the guard page.
+
+   That would just expand the mapping down to create a new guard page,
+   so there really is no point in trying to lock it in place.
+
+It would perhaps be nice to show the guard page specially in
+/proc/<pid>/maps (or at least mark grow-down segments some way), but
+let's not open ourselves up to more breakage by user space from programs
+that depends on the exact deails of the 'maps' file.
+
+Special thanks to Henrique de Moraes Holschuh for diving into lvm-tools
+source code to see what was going on with the whole new warning.
+
+Reported-and-tested-by: François Valenduc <francois.valenduc@tvcablenet.be
+Reported-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
+Cc: stable@kernel.org
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+---
+
+diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
+index aea1d3f..439fc1f 100644
+--- a/fs/proc/task_mmu.c
++++ b/fs/proc/task_mmu.c
+@@ -210,6 +210,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
+ 	int flags = vma->vm_flags;
+ 	unsigned long ino = 0;
+ 	unsigned long long pgoff = 0;
++	unsigned long start;
+ 	dev_t dev = 0;
+ 	int len;
+ 
+@@ -220,8 +221,13 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
+ 		pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
+ 	}
+ 
++	/* We don't show the stack guard page in /proc/maps */
++	start = vma->vm_start;
++	if (vma->vm_flags & VM_GROWSDOWN)
++		start += PAGE_SIZE;
++
+ 	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
+-			vma->vm_start,
++			start,
+ 			vma->vm_end,
+ 			flags & VM_READ ? 'r' : '-',
+ 			flags & VM_WRITE ? 'w' : '-',
+diff --git a/mm/mlock.c b/mm/mlock.c
+index 3f82720..49e5e4c 100644
+--- a/mm/mlock.c
++++ b/mm/mlock.c
+@@ -167,6 +167,14 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma,
+ 	if (vma->vm_flags & VM_WRITE)
+ 		gup_flags |= FOLL_WRITE;
+ 
++	/* We don't try to access the guard page of a stack vma */
++	if (vma->vm_flags & VM_GROWSDOWN) {
++		if (start == vma->vm_start) {
++			start += PAGE_SIZE;
++			nr_pages--;
++		}
++	}
++
+ 	while (nr_pages > 0) {
+ 		int i;
+