On Mon, 10 Jun 2013 10:23:49 -0700 Davidlohr Bueso <davidlohr.bu...@hp.com> wrote:
> On Mon, 2013-06-10 at 12:14 -0400, Sasha Levin wrote: > > ipc_addid() is protected by a rcu read lock, which means we can't allocate > > using GFP_KERNEL inside it. > > > > Signed-off-by: Sasha Levin <sasha.le...@oracle.com> > > --- > > > > Another option would be to call idr_preload from outside the read lock, > > but that complicates the code much more than this fix. If that's the > > preferred method to fix it I can resend that solution instead. > > > > This issue was reported last week by Fengguang > (http://www.spinics.net/lists/kernel/msg1545633.html#.UbYI9qqdmV8) > > Your fix looks the simplest approach, but I'm not sure if doing the > atomic allocation would trigger some other problem, as a side effect. > Andrew? It will fix the issue. But GFP_ATOMIC is much less reliable than GFP_KERNEL and such a switch should be viewed as a lame act of last resort. > A third option would be to simply revert the offending commit, leaving > the rcu locking as it originally was. That patch has other issues, as I described yesterday. But there are ten follow-on patches to that one and I assume that dropping ipc-move-rcu-lock-out-of-ipc_addid.patch will create a mess. It will also create a combination which hasn't been tested by anyone. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
