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	Wed, 15 Jul 2009 14:18:13 -0400
Subject: Re: [PATCH] mac80211: don't sleep in mesh_path_add allocation
From: Johannes Berg <johannes@sipsolutions.net>
To: Andrey Yurovsky <andrey@cozybit.com>
Cc: linux-wireless@vger.kernel.org, javier@cozybit.com
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Date: Wed, 15 Jul 2009 20:17:43 +0200
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On Wed, 2009-07-15 at 11:02 -0700, Andrey Yurovsky wrote:
> mesh_path_add allocates an mpath and a node but it is called with RCU
> held.  Use the GFP_ATOMIC flag to prevent these allocations from
> sleeping since otherwise we can hit the following sleep-while-atomic:

This isn't sufficient, quoting from the function, highlight added:

int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata)
{
...
        if (grow) {
                struct mesh_table *oldtbl, *newtbl;

                write_lock(&pathtbl_resize_lock);
                oldtbl =3D mesh_paths;
                newtbl =3D mesh_table_grow(mesh_paths);
                if (!newtbl) {
                        write_unlock(&pathtbl_resize_lock);
                        return 0;
                }
                rcu_assign_pointer(mesh_paths, newtbl);
                write_unlock(&pathtbl_resize_lock);

*******         synchronize_rcu();
                mesh_table_free(oldtbl, false);
        }
...
}

johannes

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