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

Commit Message

Alexandre Ghiti June 19, 2019, 5:08 a.m. UTC

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 <[e-mail]>
---
 mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

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);
 	}