From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Chinner Date: Thu, 20 Dec 2007 04:34:29 +0000 Subject: Re: [ia64] BUG: sleeping in atomic Message-Id: <20071220043429.GO4612@sgi.com> List-Id: References: <20071219055430.GV4396912@sgi.com> <20071219164204.GA18161@fattire.cabal.ca> In-Reply-To: <20071219164204.GA18161@fattire.cabal.ca> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Kyle McMartin Cc: David Chinner , lkml , tony.luck@intel.com, linux-ia64@vger.kernel.org On Wed, Dec 19, 2007 at 11:42:04AM -0500, Kyle McMartin wrote: > On Wed, Dec 19, 2007 at 04:54:30PM +1100, David Chinner wrote: > > [ 5667.086055] BUG: sleeping function called from invalid context at kernel/fork.c:401 > > > > The problem is that mmput is called under the read_lock by > find_thread_for_addr... The comment above seems to indicate that gdb > needs to be able to access any child tasks register backing store > memory... This seems pretty broken. > > cheers, Kyle > > --- > > Who knows, maybe gdb is saner now? > > diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c > index 2e96f17..b609704 100644 > --- a/arch/ia64/kernel/ptrace.c > +++ b/arch/ia64/kernel/ptrace.c > @@ -1418,7 +1418,7 @@ asmlinkage long > sys_ptrace (long request, pid_t pid, unsigned long addr, unsigned long data) > { > struct pt_regs *pt; > - unsigned long urbs_end, peek_or_poke; > + unsigned long urbs_end; > struct task_struct *child; > struct switch_stack *sw; > long ret; > @@ -1430,23 +1430,12 @@ sys_ptrace (long request, pid_t pid, unsigned long addr, unsigned long data) > goto out; > } > > - peek_or_poke = (request = PTRACE_PEEKTEXT > - || request = PTRACE_PEEKDATA > - || request = PTRACE_POKETEXT > - || request = PTRACE_POKEDATA); > - ret = -ESRCH; > - read_lock(&tasklist_lock); > - { > - child = find_task_by_pid(pid); > - if (child) { > - if (peek_or_poke) > - child = find_thread_for_addr(child, addr); > - get_task_struct(child); > - } > - } > - read_unlock(&tasklist_lock); > - if (!child) > + child = ptrace_get_task_struct(pid); > + if (IS_ERR(child)) { > + ret = PTR_ERR(child); > goto out; > + } > + > ret = -EPERM; > if (pid = 1) /* no messing around with init! */ > goto out_tsk; Yes, this patch fixes the problem (though I haven't tried to use gdb yet). Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group