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Remove nid_lock from alloc_fresh_huge_page

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The fix to that race in alloc_fresh_huge_page() which could give an illegal
node ID did not need nid_lock at all: the fix was to replace static int nid
by static int prev_nid and do the work on local int nid.  nid_lock did make
sure that racers strictly roundrobin the nodes, but that's not something we
need to enforce strictly.  Kill nid_lock.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2007-07-19 01:49:11 -07:00 committed by Linus Torvalds
parent e3aded3cc2
commit 7ed5cb2b73
1 changed files with 7 additions and 3 deletions
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10
mm/hugetlb.c
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@ -104,15 +104,19 @@ static int alloc_fresh_huge_page(void)
{
static int prev_nid;
struct page *page;
static DEFINE_SPINLOCK(nid_lock);
int nid;
spin_lock(&nid_lock);
/*
* Copy static prev_nid to local nid, work on that, then copy it
* back to prev_nid afterwards: otherwise there's a window in which
* a racer might pass invalid nid MAX_NUMNODES to alloc_pages_node.
* But we don't need to use a spin_lock here: it really doesn't
* matter if occasionally a racer chooses the same nid as we do.
*/
nid = next_node(prev_nid, node_online_map);
if (nid == MAX_NUMNODES)
nid = first_node(node_online_map);
prev_nid = nid;
spin_unlock(&nid_lock);
page = alloc_pages_node(nid, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
HUGETLB_PAGE_ORDER);