Messages in this thread Patch in this message | | | Date | Thu, 14 Feb 2013 16:47:48 -0800 | From | "Paul E. McKenney" <> | Subject | Re: rcu: fix hlist_bl_set_first_rcu annotation |
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On Fri, Feb 15, 2013 at 12:01:30AM +0000, Andrew Price wrote: > Hi, > > On 03/02/13 18:39, Paul E. McKenney wrote: > >On Wed, Jan 30, 2013 at 07:07:57PM +0000, Steven Whitehouse wrote: > >> > >>Abhi noticed that we were getting a complaint from the RCU subsystem > >>about access of an RCU protected list under the write side bit lock. > >>This patch adds additional annotation to check both the RCU read > >>lock and the write side bit lock before printing a message. > >> > >>Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> > >>Reported-by: Abhijith Das <adas@redhat.com> > >>Tested-by: Abhijith Das <adas@redhat.com> > > > >Looks plausible to me on first glance, copying Nick Piggin and Christoph > >Hellwig. If they have no objections, I will queue this. > > > > Thanx, Paul > > Has this had any attention yet? I'm also seeing the complaint quite > frequently: > > [ 68.738811] =============================== > [ 68.741380] [ INFO: suspicious RCU usage. ] > [ 68.748785] 3.8.0-0.rc7.git1.1.fc19.x86_64 #1 Not tainted > [ 68.750841] ------------------------------- > [ 68.752418] include/linux/rculist_bl.h:23 suspicious > rcu_dereference_check() usage! > [ 68.755264] > [ 68.755264] other info that might help us debug this: > [ 68.755264] > [ 68.758030] > [ 68.758030] rcu_scheduler_active = 1, debug_locks = 0 > [ 68.760316] 1 lock held by mount/476: > [ 68.761896] #0: (&type->s_umount_key#38/1){+.+.+.}, at: > [<ffffffff811dbbee>] sget+0x39e/0x670 > [ 68.767115] > [ 68.767115] stack backtrace: > [ 68.769529] Pid: 476, comm: mount Not tainted > 3.8.0-0.rc7.git1.1.fc19.x86_64 #1 > [ 68.772095] Call Trace: > [ 68.772995] [<ffffffff810d73b7>] lockdep_rcu_suspicious+0xe7/0x120 > [ 68.775184] [<ffffffffa00e3238>] search_bucket+0x118/0x160 [gfs2] > [ 68.777559] [<ffffffffa00e47c3>] gfs2_glock_get+0x603/0x7b0 [gfs2] > [ 68.780749] [<ffffffffa00e41c5>] ? gfs2_glock_get+0x5/0x7b0 [gfs2] > [ 68.784173] [<ffffffffa00e6db9>] gfs2_glock_nq_num+0x29/0x90 [gfs2] > [ 68.786551] [<ffffffffa00f2b79>] gfs2_mount+0x869/0xf30 [gfs2] > [ 68.788672] [<ffffffff810ad428>] ? sched_clock_cpu+0xa8/0x100 > [ 68.790739] [<ffffffff810d561d>] ? trace_hardirqs_off+0xd/0x10 > [ 68.793042] [<ffffffff810ad56f>] ? local_clock+0x5f/0x70 > [ 68.794940] [<ffffffff81702500>] ? __mutex_unlock_slowpath+0x80/0x170 > [ 68.798236] [<ffffffff811dcb49>] mount_fs+0x39/0x1b0 > [ 68.800409] [<ffffffff811879c0>] ? __alloc_percpu+0x10/0x20 > [ 68.803692] [<ffffffff811fa8e3>] vfs_kern_mount+0x63/0xf0 > [ 68.806773] [<ffffffff811fcfb5>] do_mount+0x205/0xa90 > [ 68.809669] [<ffffffff8118c8ec>] ? might_fault+0x5c/0xb0 > [ 68.812717] [<ffffffff811819fb>] ? strndup_user+0x4b/0xf0 > [ 68.816066] [<ffffffff811fd8c3>] sys_mount+0x83/0xc0 > [ 68.818284] [<ffffffff8170ead9>] system_call_fastpath+0x16/0x1b > > It would be good to have this silenced for 3.8 but I think there's > not long to go.
I have queued this, thank you.
3.8 is getting close to the end, but there is always -stable if the 3.8 series is of particular interest for this bug.
Thanx, Paul
> Thanks, > Andy > > >>diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h > >>index 31f9d75..2eb8855 100644 > >>--- a/include/linux/list_bl.h > >>+++ b/include/linux/list_bl.h > >>@@ -125,6 +125,11 @@ static inline void hlist_bl_unlock(struct hlist_bl_head *b) > >> __bit_spin_unlock(0, (unsigned long *)b); > >> } > >> > >>+static inline bool hlist_bl_is_locked(struct hlist_bl_head *b) > >>+{ > >>+ return bit_spin_is_locked(0, (unsigned long *)b); > >>+} > >>+ > >> /** > >> * hlist_bl_for_each_entry - iterate over list of given type > >> * @tpos: the type * to use as a loop cursor. > >>diff --git a/include/linux/rculist_bl.h b/include/linux/rculist_bl.h > >>index cf1244f..4f216c5 100644 > >>--- a/include/linux/rculist_bl.h > >>+++ b/include/linux/rculist_bl.h > >>@@ -20,7 +20,7 @@ static inline void hlist_bl_set_first_rcu(struct hlist_bl_head *h, > >> static inline struct hlist_bl_node *hlist_bl_first_rcu(struct hlist_bl_head *h) > >> { > >> return (struct hlist_bl_node *) > >>- ((unsigned long)rcu_dereference(h->first) & ~LIST_BL_LOCKMASK); > >>+ ((unsigned long)rcu_dereference_check(h->first, hlist_bl_is_locked(h)) & ~LIST_BL_LOCKMASK); > >> } > >> > >> /** > >> > >> >
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