This is a note to let you know that I've just added the patch titled
mm: allow arch code to control the user page table ceiling
to the 3.4-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:
mm-allow-arch-code-to-control-the-user-page-table-ceiling.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6ee8630e02be6dd89926ca0fbc21af68b23dc087 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Mon, 29 Apr 2013 15:07:44 -0700
Subject: mm: allow arch code to control the user page table ceiling
From: Hugh Dickins <hughd@xxxxxxxxxx>
commit 6ee8630e02be6dd89926ca0fbc21af68b23dc087 upstream.
On architectures where a pgd entry may be shared between user and kernel
(e.g. ARM+LPAE), freeing page tables needs a ceiling other than 0.
This patch introduces a generic USER_PGTABLES_CEILING that arch code can
override. It is the responsibility of the arch code setting the ceiling
to ensure the complete freeing of the page tables (usually in
pgd_free()).
[catalin.marinas@xxxxxxx: commit log; shift_arg_pages(), asm-generic/pgtables.h changes]
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/exec.c | 4 ++--
include/asm-generic/pgtable.h | 10 ++++++++++
mm/mmap.c | 4 ++--
3 files changed, 14 insertions(+), 4 deletions(-)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -627,7 +627,7 @@ static int shift_arg_pages(struct vm_are
* when the old and new regions overlap clear from new_end.
*/
free_pgd_range(&tlb, new_end, old_end, new_end,
- vma->vm_next ? vma->vm_next->vm_start : 0);
+ vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
} else {
/*
* otherwise, clean from old_start; this is done to not touch
@@ -636,7 +636,7 @@ static int shift_arg_pages(struct vm_are
* for the others its just a little faster.
*/
free_pgd_range(&tlb, old_start, old_end, new_end,
- vma->vm_next ? vma->vm_next->vm_start : 0);
+ vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
}
tlb_finish_mmu(&tlb, new_end, old_end);
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -7,6 +7,16 @@
#include <linux/mm_types.h>
#include <linux/bug.h>
+/*
+ * On almost all architectures and configurations, 0 can be used as the
+ * upper ceiling to free_pgtables(): on many architectures it has the same
+ * effect as using TASK_SIZE. However, there is one configuration which
+ * must impose a more careful limit, to avoid freeing kernel pgtables.
+ */
+#ifndef USER_PGTABLES_CEILING
+#define USER_PGTABLES_CEILING 0UL
+#endif
+
#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
extern int ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep,
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1920,7 +1920,7 @@ static void unmap_region(struct mm_struc
unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
vm_unacct_memory(nr_accounted);
free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
- next ? next->vm_start : 0);
+ next ? next->vm_start : USER_PGTABLES_CEILING);
tlb_finish_mmu(&tlb, start, end);
}
@@ -2308,7 +2308,7 @@ void exit_mmap(struct mm_struct *mm)
unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
vm_unacct_memory(nr_accounted);
- free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
+ free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
tlb_finish_mmu(&tlb, 0, -1);
/*
Patches currently in stable-queue which might be from hughd@xxxxxxxxxx are
queue-3.4/mm-allow-arch-code-to-control-the-user-page-table-ceiling.patch
queue-3.4/arm-set-the-page-table-freeing-ceiling-to-task_size.patch
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