From: Chris Wright <chrisw@osdl.org>
The topdown changes in 2.6.12-rc1 can cause large allocations with large
stack limit to fail, despite there being space available. The
mmap_base-len is only valid when len >= mmap_base. However, nothing in
topdown allocator checks this. It's only (now) caught at higher level,
which will cause allocation to simply fail. The following change restores
the fallback to bottom-up path, which will allow large allocations with
large stack limit to potentially still succeed.
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
mm/mmap.c | 4 ++++
1 files changed, 4 insertions(+)
diff -puN mm/mmap.c~mmap-topdown-fix-for-large-stack-limit-large-allocation mm/mmap.c
--- 25/mm/mmap.c~mmap-topdown-fix-for-large-stack-limit-large-allocation 2005-05-31 02:43:55.000000000 -0700
+++ 25-akpm/mm/mmap.c 2005-05-31 02:43:55.000000000 -0700
@@ -1267,6 +1267,9 @@ arch_get_unmapped_area_topdown(struct fi
return (mm->free_area_cache = addr-len);
}
+ if (mm->mmap_base < len)
+ goto bottomup;
+
addr = mm->mmap_base-len;
do {
@@ -1288,6 +1291,7 @@ arch_get_unmapped_area_topdown(struct fi
addr = vma->vm_start-len;
} while (len < vma->vm_start);
+bottomup:
/*
* A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario
_