From: Hugh Dickins <hugh@veritas.com>
Date: Sat, 28 Oct 2006 17:38:43 +0000 (-0700)
Subject: [PATCH] hugetlb: fix prio_tree unit
X-Git-Tag: v2.6.19-rc4~50
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=856fc29505556cf263f3dcda2533cf3766c14ab6;p=pandora-kernel.git

[PATCH] hugetlb: fix prio_tree unit

hugetlb_vmtruncate_list was misconverted to prio_tree: its prio_tree is in
units of PAGE_SIZE (PAGE_CACHE_SIZE) like any other, not HPAGE_SIZE (whereas
its radix_tree is kept in units of HPAGE_SIZE, otherwise slots would be
absurdly sparse).

At first I thought the error benign, just calling __unmap_hugepage_range on
more vmas than necessary; but on 32-bit machines, when the prio_tree is
searched correctly, it happens to ensure the v_offset calculation won't
overflow.  As it stood, when truncating at or beyond 4GB, it was liable to
discard pages COWed from lower offsets; or even to clear pmd entries of
preceding vmas, triggering exit_mmap's BUG_ON(nr_ptes).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

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