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maple_tree: remove rcu_read_lock() from mt_validate()

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The write lock should be held when validating the tree to avoid updates
racing with checks.  Holding the rcu read lock during a large tree
validation may also cause a prolonged rcu read window and "rcu_preempt
detected stalls" warnings.

Link: https://lore.kernel.org/all/0000000000001d12d4062005aea1@google.com/
Link: https://lkml.kernel.org/r/20240820175417.2782532-1-Liam.Howlett@oracle.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reported-by: syzbot+036af2f0c7338a33b0cd@syzkaller.appspotmail.com
Cc: Hillf Danton <hdanton@sina.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam R. Howlett 2024-08-20 13:54:17 -04:00 committed by Andrew Morton
parent 6dacd79d28
commit f806de88d8
1 changed files with 2 additions and 5 deletions
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7
lib/maple_tree.c
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@ -7566,14 +7566,14 @@ static void mt_validate_nulls(struct maple_tree *mt)
* 2. The gap is correctly set in the parents
*/
void mt_validate(struct maple_tree *mt)
__must_hold(mas->tree->ma_lock)
{
unsigned char end;
MA_STATE(mas, mt, 0, 0);
rcu_read_lock();
mas_start(&mas);
if (!mas_is_active(&mas))
goto done;
return;
while (!mte_is_leaf(mas.node))
mas_descend(&mas);
@ -7594,9 +7594,6 @@ void mt_validate(struct maple_tree *mt)
mas_dfs_postorder(&mas, ULONG_MAX);
}
mt_validate_nulls(mt);
done:
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(mt_validate);