Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759439AbXIROtz (ORCPT ); Tue, 18 Sep 2007 10:49:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758806AbXIROts (ORCPT ); Tue, 18 Sep 2007 10:49:48 -0400 Received: from ecfrec.frec.bull.fr ([129.183.4.8]:59771 "EHLO ecfrec.frec.bull.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754735AbXIROtr (ORCPT ); Tue, 18 Sep 2007 10:49:47 -0400 Message-ID: <46EFE6D7.3070105@bull.net> Date: Tue, 18 Sep 2007 16:55:19 +0200 From: Nadia Derbey Organization: BULL/DT/OSwR&D/Linux User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040115 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andrew Morton Cc: Alexey Dobriyan , linux-kernel@vger.kernel.org Subject: Re: 2.6.23-rc6-mm1: IPC: sleeping function called ... References: <20070918091728.GA6766@localhost.sw.ru> <20070918032727.c07aa521.akpm@linux-foundation.org> In-Reply-To: <20070918032727.c07aa521.akpm@linux-foundation.org> X-MIMETrack: Itemize by SMTP Server on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 18/09/2007 16:55:33, Serialize by Router on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 18/09/2007 16:55:35, Serialize complete at 18/09/2007 16:55:35 Content-Type: multipart/mixed; boundary="------------020104090001010406080904" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3759 Lines: 133 This is a multi-part message in MIME format. --------------020104090001010406080904 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii; format=flowed Andrew Morton wrote: > On Tue, 18 Sep 2007 13:17:28 +0400 Alexey Dobriyan wrote: > > >>I'm getting tons of this, and X fails to start >> >>CONFIG_SYSVIPC=y >>CONFIG_SYSVIPC_SYSCTL=y >># CONFIG_PREEMPT_NONE is not set >># CONFIG_PREEMPT_VOLUNTARY is not set >>CONFIG_PREEMPT=y >>CONFIG_PREEMPT_BKL=y >>CONFIG_DEBUG_PREEMPT=y >> >>BUG: sleeping function called from invalid context at kernel/rwsem.c:47 >>in_atomic():1, irqs_disabled():0 > > > OK, this fixes the locking here: > > --- a/ipc/util.c~ipc-integrate-ipc_checkid-into-ipc_lock-fix-2 > +++ a/ipc/util.c > @@ -295,7 +295,6 @@ int ipc_addid(struct ipc_ids* ids, struc > > spin_lock_init(&new->lock); > new->deleted = 0; > - rcu_read_lock(); > spin_lock(&new->lock); > return id; > } > @@ -691,7 +690,7 @@ struct kern_ipc_perm *ipc_lock(struct ip > rcu_read_unlock(); > return ERR_PTR(-EINVAL); > } > - > + rcu_read_unlock(); > return out; > } > Well, reviewing the code I found another place where the rcu_read_unlock() was missing. I'm so sorry for the inconvenience. It's true that I should have tested with CONFIG_PREEMPT=y :-( Now, the ltp tests pass even with this option set... In attachment you'll find a patch thhat 1) adds the missing rcu_read_unlock() 2) replaces Andrew's fix with a new one: the rcu_read_lock() is now taken in ipc_lock() / ipc_lock_by_ptr() and released in ipc_unlock(), exactly as it was done in the ref code. Regards, Nadia --------------020104090001010406080904 Content-Transfer-Encoding: 7bit Content-Type: text/x-patch; name="ipc_missing_rcu_locks.patch" Content-Disposition: inline; filename="ipc_missing_rcu_locks.patch" This patch fixes the missing rcu_read_(un)lock in the ipc code Signed-off-by: Nadia Derbey --- ipc/util.c | 3 ++- ipc/util.h | 4 +++- 2 files changed, 5 insertions(+), 2 deletions(-) Index: linux-2.6.23-rc6-mm1/ipc/util.c =================================================================== --- linux-2.6.23-rc6-mm1.orig/ipc/util.c 2007-09-18 16:39:43.000000000 +0200 +++ linux-2.6.23-rc6-mm1/ipc/util.c 2007-09-18 16:40:53.000000000 +0200 @@ -295,6 +295,7 @@ int ipc_addid(struct ipc_ids* ids, struc spin_lock_init(&new->lock); new->deleted = 0; + rcu_read_lock(); spin_lock(&new->lock); return id; } @@ -690,7 +691,7 @@ struct kern_ipc_perm *ipc_lock(struct ip rcu_read_unlock(); return ERR_PTR(-EINVAL); } - rcu_read_unlock(); + return out; } Index: linux-2.6.23-rc6-mm1/ipc/util.h =================================================================== --- linux-2.6.23-rc6-mm1.orig/ipc/util.h 2007-09-18 14:55:31.000000000 +0200 +++ linux-2.6.23-rc6-mm1/ipc/util.h 2007-09-18 16:41:37.000000000 +0200 @@ -141,12 +141,14 @@ static inline int ipc_checkid(struct ipc static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm) { + rcu_read_lock(); spin_lock(&perm->lock); } static inline void ipc_unlock(struct kern_ipc_perm *perm) { spin_unlock(&perm->lock); + rcu_read_unlock(); } static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, @@ -159,7 +161,7 @@ static inline struct kern_ipc_perm *ipc_ return out; if (ipc_checkid(ids, out, id)) { - spin_unlock(&out->lock); + ipc_unlock(out); return ERR_PTR(-EIDRM); } --------------020104090001010406080904-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/