Re: [PATCH v2] ipc/sem: do not sleep with a spin lock held

[Manfred Spraul]

Hi Jiri,

On 1/3/22 10:27, Jiri Slaby wrote:
> On 23. 12. 21, 4:12, cgel.zte@xxxxxxxxx wrote:
> > From: Minghao Chi <chi.minghao@xxxxxxxxxx>
> >
> > We can't call kvfree() with a spin lock held, so defer it.
>
> Sorry, defer what?
First drop the spinlock, then call kvfree().


> There are attempts to fix kvfree instead, not sure which of these 
> approaches (fix kvfree or its callers) won in the end?
Exactly. We have three options - but noone volunteered yet to decide:

- change ipc/sem.c [minimal change]

- change kvfree() to use vfree_atomic() [would also fix other changes 
that did s/kfree/kvfree/]

- Modify the vma handling so that it becomes safe to call vfree() while 
holding a spinlock. [perfect approach, but I'm concerned about side effects]


--

    Manfred