Re: [BUG] mm/vmalloc: ___might_sleep is called under a spinlock in __purge_vmap_area_lazy

[Jia-Ju Bai]

Thanks for your reply and explanation :)
I will improve my analysis.

Thanks,
Jia-Ju Bai

On 2017/10/9 12:10, Kirill A. Shutemov wrote:
> On Mon, Oct 09, 2017 at 12:00:33PM +0800, Jia-Ju Bai wrote:
> > The ___might_sleep is called under a spinlock, and the function call graph
> > is:
> > __purge_vmap_area_lazy (acquire the spinlock)
> >    cond_resched_lock
> >      ___might_sleep
> >
> > In this situation, ___might_sleep may prints error log message because a
> > spinlock is held.
> > A possible fix is to remove ___might_sleep in cond_resched_lock.
> >
> > This bug is found by my static analysis tool and my code review.
> This analysis doesn't makes sense.
>
> The point of cond_resched_lock() is that it drops the lock, if resched is
> required.
>
> ___might_sleep() is called with preempt_offset equal to
> PREEMPT_LOCK_OFFSET, so it won't report error if it's the only lock we
> hold.