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Date: Sat, 27 Jul 2013 21:34:39 +0800 From: Fengguang Wu <fengguang.wu@...el.com> To: Davidlohr Bueso <davidlohr.bueso@...com> Cc: Xiaotian Feng <xtfeng@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, linux-kernel <linux-kernel@...r.kernel.org>, Sasha Levin <sasha.levin@...cle.com> Subject: Re: [ipc,shm] BUG: lock held when returning to user space! On Sat, Jul 20, 2013 at 09:46:45AM -0700, Davidlohr Bueso wrote: > On Sun, 2013-07-21 at 00:02 +0800, Xiaotian Feng wrote: > > On Sat, Jul 20, 2013 at 9:13 PM, Fengguang Wu <fengguang.wu@...el.com> wrote: > > > Greetings, > > > > > > I got the below dmesg and the first bad commit is > > > > > > commit c5d0282a0405b0a81fa3390e4230e4cbb3ced7a2 > > > Author: Davidlohr Bueso <davidlohr.bueso@...com> > > > Date: Fri Jul 19 09:56:58 2013 +1000 > > > > > > ipc,shm: shorten critical region for shmat > > > > > > Similar to other system calls, acquire the kern_ipc_perm lock after doing > > > the initial permission and security checks. > > > > > > Signed-off-by: Davidlohr Bueso <davidlohr.bueso@...com> > > > Tested-by: Sedat Dilek <sedat.dilek@...il.com> > > > Cc: Rik van Riel <riel@...hat.com> > > > Cc: Manfred Spraul <manfred@...orfullife.com> > > > Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> > > > > > > [ 20.702156] > > > [ 20.702493] ================================================ > > > [ 20.703511] [ BUG: lock held when returning to user space! ] > > > [ 20.704532] 3.11.0-rc1-next-20130719 #50 Not tainted > > > [ 20.705416] ------------------------------------------------ > > > [ 20.706425] trinity-child0/174 is leaving the kernel with locks still held! > > > [ 20.707638] 1 lock held by trinity-child0/174: > > > [ 20.708475] #0: (rcu_read_lock){.+.+..}, at: [<ffffffff814a8491>] do_shmat+0xe1/0x500 > > > > > > > ---- > > ns = current->nsproxy->ipc_ns; > > - shp = shm_lock_check(ns, shmid); > > + rcu_read_lock(); > > + shp = shm_obtain_object_check(ns, shmid); > > if (IS_ERR(shp)) { > > err = PTR_ERR(shp); > > goto out; > > ---- > > > > If shm_obtain_object_check() failed, goto out will return with > > rcu_read_lock() held. I think following patch should cure this. > > Yep that should solve it, sorry about that. Sasha Levin sent out a fix > for it yesterday (offline). What's the patch's status? The bug is still there in linux-next 20130726. Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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