parisc: fix find_extend_vma() breakage

The STACK_GROWSUP case of stack expansion was missing a test for 'prev',
which got removed by commit cb8f488c33539f096580e202f5438a809195008f
("mmap.c: deinline a few functions") by mistake.

I found my original email in "sent" folder. The patch in that mail
does NOT remove !prev. That change had beed added by someone else.

Ok, I think we are not much interested in who did it, let's
fix it for good.

[ "It looks like this was caused by me fixing rejects.  That was the
  fancy include-lots-of-context-so-it-wont-apply patch." - akpm ]

Reported-and-bisected-by: Helge Deller <deller@gmx.de>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index de14ac2..d4855a6 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1704,7 +1704,7 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
        vma = find_vma_prev(mm, addr, &prev);
        if (vma && (vma->vm_start <= addr))
                return vma;
-       if (expand_stack(prev, addr))
+       if (!prev || expand_stack(prev, addr))
                return NULL;
        if (prev->vm_flags & VM_LOCKED) {
                if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)