On Thu, Jul 12, 2018 at 3:48 PM Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > > Quoting Jordan Crouse (2018-07-12 19:59:25) > > Do a bit of cleanup to prepare for upcoming changes to pass the > > hanging task comm and cmdline to the crash dump function. > > > > Signed-off-by: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/msm/msm_gpu.c | 18 ++++++++++-------- > > 1 file changed, 10 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c > > index 1c09acfb4028..2ca354047250 100644 > > --- a/drivers/gpu/drm/msm/msm_gpu.c > > +++ b/drivers/gpu/drm/msm/msm_gpu.c > > @@ -314,6 +314,7 @@ static void recover_worker(struct work_struct *work) > > struct msm_drm_private *priv = dev->dev_private; > > struct msm_gem_submit *submit; > > struct msm_ringbuffer *cur_ring = gpu->funcs->active_ring(gpu); > > + char *comm = NULL, *cmd = NULL; > > int i; > > > > mutex_lock(&dev->struct_mutex); > > @@ -327,7 +328,7 @@ static void recover_worker(struct work_struct *work) > > rcu_read_lock(); > > task = pid_task(submit->pid, PIDTYPE_PID); > > if (task) { > > - char *cmd; > > + comm = kstrdup(task->comm, GFP_KERNEL); > > Under rcu_read_lock(), GFP_KERNEL is not allowed, you need GFP_NOWAIT or > some such (or grab a reference to the pid and drop rcu then GFP_KERNEL). I started looking at a similar issue w/ our use of kstrdup_quotable_cmdline() under rcu_read_lock().. I *guess* I hadn't noticed it before due to different RCU kconfig? I can use GFP_ATOMIC, and I can fix kstrdup_quotable_cmdline() to actually use gfp flags passed in for kmalloc() (and similar bug in kstrdup_quotable_file()).. but get_cmdline() still grabs mmap_sem which complains under rcu_read_lock().. is there any way to ensure the tast_struct sticks around long enough to get it's cmdline without holding rcu_read_lock()? I couldn't find any refcnt'ing on task_struct itself, which makes this seem a bit unsolveable :-/ BR, -R -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html