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[PATCH] mmap topdown fix for large stack limit, large allocation

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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>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Chris Wright 2005-06-21 17:14:52 -07:00 committed by Linus Torvalds
parent 1363c3cd86
commit 73219d1780
1 changed files with 4 additions and 0 deletions
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4
mm/mmap.c
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@ -1267,6 +1267,9 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
return (mm->free_area_cache = addr-len); return (mm->free_area_cache = addr-len);
} }
if (mm->mmap_base < len)
goto bottomup;
addr = mm->mmap_base-len; addr = mm->mmap_base-len;
do { do {
@ -1288,6 +1291,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
addr = vma->vm_start-len; addr = vma->vm_start-len;
} while (len < vma->vm_start); } while (len < vma->vm_start);
bottomup:
/* /*
* A failed mmap() very likely causes application failure, * A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario * so fall back to the bottom-up function here. This scenario