(Fix Serge's email) On 07/27, Oleg Nesterov wrote: > > On 07/27, Toralf Förster wrote: > > > > I do have a user mode linux image (stable 32 bit Gentoo Linux ) which erratically crashes > > while fuzz tested with trinity if the victim files are located on a NFS share. > > > > The back trace of the core dumps always looks like the attached. > > > > To bisect it is hard. However after few attempts in the last weeks the following > > commit is either the first bad commit or at least the upper limit (less likely). > > > > > > commit 8aac62706adaaf0fab02c4327761561c8bda9448 > > Author: Oleg Nesterov <oleg@xxxxxxxxxx> > > Date: Fri Jun 14 21:09:49 2013 +0200 > > > > move exit_task_namespaces() outside of exit_notify() > > > > #15 nlmclnt_setlockargs (req=0x48e18860, fl=0x48f27c8c) at fs/lockd/clntproc.c:131 > > Thanks. > > So nlmclnt_setlockargs()->utsname() crashes and we probably need > the patch below. > > But is it correct? I know _absolutely_ nothing about nfs/sunrpc/etc and > I never looked into this code before, most probably I am wrong. > > But it seems that __nlm_async_call() relies on workqueues. > nlmclnt_async_call() does rpc_wait_for_completion_task(), but what if > the caller is killed? > > nlm_rqst can't go away, ->a_count was incremented. But can't the caller > exit before call->name is used? I meant lock->caller, sorry. > In this case the memory it points to > can be already freed. And of course I have no idea what lock->caller actually means. But note that the final fput() can be called by another process from the different namespace. Say, a task from the parent namespace looks at /proc/pid/fd. But again. I do not understand this code at all. > Oleg. > > --- x/kernel/exit.c > +++ x/kernel/exit.c > @@ -783,8 +783,8 @@ void do_exit(long code) > exit_shm(tsk); > exit_files(tsk); > exit_fs(tsk); > - exit_task_namespaces(tsk); > exit_task_work(tsk); > + exit_task_namespaces(tsk); > check_stack_usage(); > exit_thread(); > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
