Messages in this thread | | | Date | Sun, 7 Jun 2020 06:23:40 +1000 | From | Stephen Rothwell <> | Subject | Re: [PATCH RESEND] device_cgroup: Fix RCU list debugging warning |
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Hi all,
On Mon, 6 Apr 2020 16:29:50 +0530 Amol Grover <frextrite@gmail.com> wrote: > > exceptions may be traversed using list_for_each_entry_rcu() > outside of an RCU read side critical section BUT under the > protection of decgroup_mutex. Hence add the corresponding > lockdep expression to fix the following false-positive > warning: > > [ 2.304417] ============================= > [ 2.304418] WARNING: suspicious RCU usage > [ 2.304420] 5.5.4-stable #17 Tainted: G E > [ 2.304422] ----------------------------- > [ 2.304424] security/device_cgroup.c:355 RCU-list traversed in non-reader section!! > > Signed-off-by: Amol Grover <frextrite@gmail.com> > --- > security/device_cgroup.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/security/device_cgroup.c b/security/device_cgroup.c > index 7d0f8f7431ff..b7da9e0970d9 100644 > --- a/security/device_cgroup.c > +++ b/security/device_cgroup.c > @@ -352,7 +352,8 @@ static bool match_exception_partial(struct list_head *exceptions, short type, > { > struct dev_exception_item *ex; > > - list_for_each_entry_rcu(ex, exceptions, list) { > + list_for_each_entry_rcu(ex, exceptions, list, > + lockdep_is_held(&devcgroup_mutex)) { > if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK)) > continue; > if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR)) > -- > 2.24.1 >
I have been carrying the above patch in linux-next for some time now. I have been carrying it because it fixes problems for syzbot (see the third warning in https://lore.kernel.org/linux-next/CACT4Y+YnjK+kq0pfb5fe-q1bqe2T1jq_mvKHf--Z80Z3wkyK1Q@mail.gmail.com/). Is there some reason it has not been applied to some tree?
-- Cheers, Stephen Rothwell [unhandled content-type:application/pgp-signature] | |