The patch titled
radix-tree: fix radix_tree_replace_slot()
has been removed from the -mm tree. Its filename is
adix-tree-rcu-lockless-readside-fix-3.patch
This patch was dropped because it was folded into radix-tree-rcu-lockless-readside.patch
------------------------------------------------------
Subject: radix-tree: fix radix_tree_replace_slot()
From: Lee Schermerhorn <Lee.Schermerhorn@xxxxxx>
radix_tree_replace_slot() was assigning to local variable 'slot' instead of
to where pslot pointed. Changed to directly replace location pointed to by
argument pslot.
Added comments specifying required locking.
Note that we do not need to rcu_dereference() the slot to obtain the direct
pointer flag, as we hold the tree write locked.
Fixes the migration corruption that we were seeing since the rcu-radix-tree
patches went in. With this patch, we can back out
page-migration-replace-radix_tree_lookup_slot-with-radix_tree_lockup.patch
to use the more efficient direct access to radix tree slot.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/radix-tree.h | 5 ++++-
1 files changed, 4 insertions(+), 1 deletion(-)
diff -puN include/linux/radix-tree.h~adix-tree-rcu-lockless-readside-fix-3 include/linux/radix-tree.h
--- a/include/linux/radix-tree.h~adix-tree-rcu-lockless-readside-fix-3
+++ a/include/linux/radix-tree.h
@@ -133,12 +133,15 @@ static inline void *radix_tree_deref_slo
* radix_tree_replace_slot - replace item in a slot
* @pslot: pointer to slot, returned by radix_tree_lookup_slot
* @item: new item to store in the slot.
+ *
+ * For use with radix_tree_lookup_slot(). Caller must hold tree write locked
+ * across slot lookup and replacement.
*/
static inline void radix_tree_replace_slot(void *pslot, void *item)
{
void *slot = *(void **)pslot;
BUG_ON(radix_tree_is_direct_ptr(item));
- rcu_assign_pointer(slot,
+ rcu_assign_pointer(*(void **)pslot,
(void *)((unsigned long)item |
((unsigned long)slot & RADIX_TREE_DIRECT_PTR)));
}
_
Patches currently in -mm which might be from Lee.Schermerhorn@xxxxxx are
radix-tree-rcu-lockless-readside.patch
adix-tree-rcu-lockless-readside-fix-3.patch
radix-tree-cleanup-radix_tree_deref_slot-and.patch
cleanup-radix_tree_derefreplace_slot-calling-conventions.patch
cleanup-radix_tree_derefreplace_slot-calling-conventions-warning-fixes.patch
mempolicies-fix-policy_zone-check.patch
-
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