Re: possible deadlock in start_this_handle (2)

From: Matthew Wilcox
Date: Fri Feb 12 2021 - 07:25:56 EST


On Fri, Feb 12, 2021 at 08:18:11PM +0900, Tetsuo Handa wrote:
> On 2021/02/12 1:41, Michal Hocko wrote:
> > But I suspect we have drifted away from the original issue. I thought
> > that a simple check would help us narrow down this particular case and
> > somebody messing up from the IRQ context didn't sound like a completely
> > off.
> >
>
> From my experience at https://lkml.kernel.org/r/201409192053.IHJ35462.JLOMOSOFFVtQFH@xxxxxxxxxxxxxxxxxxx ,
> I think we can replace direct PF_* manipulation with macros which do not receive "struct task_struct *" argument.
> Since TASK_PFA_TEST()/TASK_PFA_SET()/TASK_PFA_CLEAR() are for manipulating PFA_* flags on a remote thread, we can
> define similar ones for manipulating PF_* flags on current thread. Then, auditing dangerous users becomes easier.

No, nobody is manipulating another task's GFP flags.