| Message ID | 20100608001234.GE2387@linux.vnet.ibm.com |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
On Mon, Jun 7, 2010 at 8:12 PM, Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote: > On Mon, Jun 07, 2010 at 02:23:17PM -0400, Miles Lane wrote: >> [ 2.677955] [ INFO: suspicious rcu_dereference_check() usage. ] >> [ 2.679089] --------------------------------------------------- >> [ 2.680276] lib/idr.c:605 invoked rcu_dereference_check() without protection! >> [ 2.681499] >> [ 2.681500] other info that might help us debug this: >> [ 2.681501] >> [ 2.685509] >> [ 2.685510] rcu_scheduler_active = 1, debug_locks = 1 >> [ 2.688221] 1 lock held by swapper/1: >> [ 2.689587] #0: (mtd_table_mutex){+.+...}, at: >> [<ffffffff812bea45>] register_mtd_user+0x1a/0x69 >> [ 2.691096] >> [ 2.691098] stack backtrace: >> [ 2.694059] Pid: 1, comm: swapper Not tainted 2.6.35-rc2-git1 #8 >> [ 2.695601] Call Trace: >> [ 2.697243] [<ffffffff81064e9c>] lockdep_rcu_dereference+0x9d/0xa5 >> [ 2.698868] [<ffffffff811b9c86>] idr_get_next+0x60/0x124 >> [ 2.700556] [<ffffffff812be779>] __mtd_next_device+0x1b/0x1d >> [ 2.702238] [<ffffffff812bea7c>] register_mtd_user+0x51/0x69 >> [ 2.703964] [<ffffffff816cca45>] init_mtdchar+0xb3/0xd3 >> [ 2.705686] [<ffffffff816cc992>] ? init_mtdchar+0x0/0xd3 >> [ 2.707470] [<ffffffff810001ef>] do_one_initcall+0x59/0x14e >> [ 2.709255] [<ffffffff816a768a>] kernel_init+0x144/0x1ce >> [ 2.711082] [<ffffffff81003054>] kernel_thread_helper+0x4/0x10 >> [ 2.712862] [<ffffffff813ca480>] ? restore_args+0x0/0x30 >> [ 2.714647] [<ffffffff816a7546>] ? kernel_init+0x0/0x1ce >> [ 2.716415] [<ffffffff81003050>] ? kernel_thread_helper+0x0/0x10 > > This looks like a new one! Does the following patch take care of it? > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit 2d54a6c31b72c902b09d365e9c66205a5c07e549 > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Date: Mon Jun 7 17:09:45 2010 -0700 > > idr: fix RCU lockdep splat in idr_get_next() > > Convert to rcu_dereference_raw() given that many callers may have many > different locking models. > > Located-by: Miles Lane <miles.lane@gmail.com> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > diff --git a/lib/idr.c b/lib/idr.c > index 2eb1dca..f099f25 100644 > --- a/lib/idr.c > +++ b/lib/idr.c > @@ -599,7 +599,7 @@ void *idr_get_next(struct idr *idp, int *nextidp) > /* find first ent */ > n = idp->layers * IDR_BITS; > max = 1 << n; > - p = rcu_dereference(idp->top); > + p = rcu_dereference_raw(idp->top); > if (!p) > return NULL; > > @@ -607,7 +607,7 @@ void *idr_get_next(struct idr *idp, int *nextidp) > while (n > 0 && p) { > n -= IDR_BITS; > *paa++ = p; > - p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]); > + p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); > } > > if (p) { > Tested. Looks good! -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jun 08, 2010 at 12:28:15AM -0400, Miles Lane wrote: > On Mon, Jun 7, 2010 at 8:12 PM, Paul E. McKenney > <paulmck@linux.vnet.ibm.com> wrote: > > On Mon, Jun 07, 2010 at 02:23:17PM -0400, Miles Lane wrote: > >> [ 2.677955] [ INFO: suspicious rcu_dereference_check() usage. ] > >> [ 2.679089] --------------------------------------------------- > >> [ 2.680276] lib/idr.c:605 invoked rcu_dereference_check() without protection! > >> [ 2.681499] > >> [ 2.681500] other info that might help us debug this: > >> [ 2.681501] > >> [ 2.685509] > >> [ 2.685510] rcu_scheduler_active = 1, debug_locks = 1 > >> [ 2.688221] 1 lock held by swapper/1: > >> [ 2.689587] #0: (mtd_table_mutex){+.+...}, at: > >> [<ffffffff812bea45>] register_mtd_user+0x1a/0x69 > >> [ 2.691096] > >> [ 2.691098] stack backtrace: > >> [ 2.694059] Pid: 1, comm: swapper Not tainted 2.6.35-rc2-git1 #8 > >> [ 2.695601] Call Trace: > >> [ 2.697243] [<ffffffff81064e9c>] lockdep_rcu_dereference+0x9d/0xa5 > >> [ 2.698868] [<ffffffff811b9c86>] idr_get_next+0x60/0x124 > >> [ 2.700556] [<ffffffff812be779>] __mtd_next_device+0x1b/0x1d > >> [ 2.702238] [<ffffffff812bea7c>] register_mtd_user+0x51/0x69 > >> [ 2.703964] [<ffffffff816cca45>] init_mtdchar+0xb3/0xd3 > >> [ 2.705686] [<ffffffff816cc992>] ? init_mtdchar+0x0/0xd3 > >> [ 2.707470] [<ffffffff810001ef>] do_one_initcall+0x59/0x14e > >> [ 2.709255] [<ffffffff816a768a>] kernel_init+0x144/0x1ce > >> [ 2.711082] [<ffffffff81003054>] kernel_thread_helper+0x4/0x10 > >> [ 2.712862] [<ffffffff813ca480>] ? restore_args+0x0/0x30 > >> [ 2.714647] [<ffffffff816a7546>] ? kernel_init+0x0/0x1ce > >> [ 2.716415] [<ffffffff81003050>] ? kernel_thread_helper+0x0/0x10 > > > > This looks like a new one! Does the following patch take care of it? > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > commit 2d54a6c31b72c902b09d365e9c66205a5c07e549 > > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Date: Mon Jun 7 17:09:45 2010 -0700 > > > > idr: fix RCU lockdep splat in idr_get_next() > > > > Convert to rcu_dereference_raw() given that many callers may have many > > different locking models. > > > > Located-by: Miles Lane <miles.lane@gmail.com> > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > > diff --git a/lib/idr.c b/lib/idr.c > > index 2eb1dca..f099f25 100644 > > --- a/lib/idr.c > > +++ b/lib/idr.c > > @@ -599,7 +599,7 @@ void *idr_get_next(struct idr *idp, int *nextidp) > > /* find first ent */ > > n = idp->layers * IDR_BITS; > > max = 1 << n; > > - p = rcu_dereference(idp->top); > > + p = rcu_dereference_raw(idp->top); > > if (!p) > > return NULL; > > > > @@ -607,7 +607,7 @@ void *idr_get_next(struct idr *idp, int *nextidp) > > while (n > 0 && p) { > > n -= IDR_BITS; > > *paa++ = p; > > - p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]); > > + p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); > > } > > > > if (p) { > > > > Tested. Looks good! Thank you very much for both locating this one and for testing the fix! I have added your Tested-by. Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/lib/idr.c b/lib/idr.c index 2eb1dca..f099f25 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -599,7 +599,7 @@ void *idr_get_next(struct idr *idp, int *nextidp) /* find first ent */ n = idp->layers * IDR_BITS; max = 1 << n; - p = rcu_dereference(idp->top); + p = rcu_dereference_raw(idp->top); if (!p) return NULL; @@ -607,7 +607,7 @@ void *idr_get_next(struct idr *idp, int *nextidp) while (n > 0 && p) { n -= IDR_BITS; *paa++ = p; - p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]); + p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); } if (p) {