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authorMikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>2011-05-09 13:01:09 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2011-05-21 15:13:07 -0700
commite277c750ea81076d8dc68694acc7994a024d83b2 (patch)
tree5bb1a87f3c6f05d348a823be4d1685431bf09bcb /mm/memory.c
parent3dead919f4cf95df59d8df06c1fa559c55571384 (diff)
Don't lock guardpage if the stack is growing up
commit a09a79f66874c905af35d5bb5e5f2fdc7b6b894d upstream. Linux kernel excludes guard page when performing mlock on a VMA with down-growing stack. However, some architectures have up-growing stack and locking the guard page should be excluded in this case too. This patch fixes lvm2 on PA-RISC (and possibly other architectures with up-growing stack). lvm2 calculates number of used pages when locking and when unlocking and reports an internal error if the numbers mismatch. [ Patch changed fairly extensively to also fix /proc/<pid>/maps for the grows-up case, and to move things around a bit to clean it all up and share the infrstructure with the /proc bits. Tested on ia64 that has both grow-up and grow-down segments - Linus ] Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Tested-by: Tony Luck <tony.luck@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c16
1 files changed, 7 insertions, 9 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 8b2bb7dcdae..c8fff702774 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1412,9 +1412,8 @@ no_page_table:
static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
{
- return (vma->vm_flags & VM_GROWSDOWN) &&
- (vma->vm_start == addr) &&
- !vma_stack_continue(vma->vm_prev, addr);
+ return stack_guard_page_start(vma, addr) ||
+ stack_guard_page_end(vma, addr+PAGE_SIZE);
}
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
@@ -1502,12 +1501,6 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
continue;
}
- /*
- * For mlock, just skip the stack guard page.
- */
- if ((gup_flags & FOLL_MLOCK) && stack_guard_page(vma, start))
- goto next_page;
-
do {
struct page *page;
unsigned int foll_flags = gup_flags;
@@ -1524,6 +1517,11 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
int ret;
unsigned int fault_flags = 0;
+ /* For mlock, just skip the stack guard page. */
+ if (foll_flags & FOLL_MLOCK) {
+ if (stack_guard_page(vma, start))
+ goto next_page;
+ }
if (foll_flags & FOLL_WRITE)
fault_flags |= FAULT_FLAG_WRITE;
if (nonblocking)