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 <[email protected]>
---
mm/mmap.c | 4 ++++
1 files changed, 4 insertions(+)
mm/mmap.c: de54acd9942f9929004921042721df5cdfe2b6c7
--- k/mm/mmap.c
+++ l/mm/mmap.c
@@ -1251,6 +1251,9 @@ 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 {
@@ -1268,6 +1271,7 @@ 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
-
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