[PATCH 5/8] mm: Start fallback top-down mmap at mm->mmap_base

From: Alexandre Ghiti
Date: Wed Jun 19 2019 - 01:20:11 EST


In case of mmap failure in top-down mode, there is no need to go through
the whole address space again for the bottom-up fallback: the goal of this
fallback is to find, as a last resort, space between the top-down mmap base
and the stack, which is the only place not covered by the top-down mmap.

Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
---
mm/mmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index dedae10cb6e2..e563145c1ff4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2185,7 +2185,7 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
if (offset_in_page(addr)) {
VM_BUG_ON(addr != -ENOMEM);
info.flags = 0;
- info.low_limit = TASK_UNMAPPED_BASE;
+ info.low_limit = arch_get_mmap_base(addr, mm->mmap_base);
info.high_limit = mmap_end;
addr = vm_unmapped_area(&info);
}
--
2.20.1