Re: [PATCH] mm: Use special value SHRINKER_REGISTERING instead list_empty() check

[Kirill Tkhai]

On 05.08.2018 03:03, Matthew Wilcox wrote:
> On Sat, Aug 04, 2018 at 09:42:05PM +0300, Kirill Tkhai wrote:
>> This is exactly the thing the patch makes. Instead of inserting a shrinker pointer
>> to idr, it inserts a fake value SHRINKER_REGISTERING there. The patch makes impossible
>> to dereference a shrinker unless it's completely registered. 
> 
> -       id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
> +       id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL);
> 
> Instead:
> 
> +       id = idr_alloc(&shrinker_idr, NULL, 0, 0, GFP_KERNEL);
> 
> ... and the rest of your patch becomes even simpler.

The patch, we are discussing at the moment, does *exactly* this:

https://lkml.org/lkml/2018/8/3/588

It looks like you missed this hunk in the patch.