Re: [PATCH] mm: swap: Avoid infinite loop if no valid swap entry found during do_swap_page

[Matthew Wilcox]

On Sat, Feb 22, 2025 at 11:59:53AM +0800, mawupeng wrote:
> 
> 
> On 2025/2/22 11:45, Matthew Wilcox wrote:
> > On Sat, Feb 22, 2025 at 10:46:17AM +0800, Wupeng Ma wrote:
> >> Digging into the source, we found that the swap entry is invalid due to
> >> unknown reason, and this lead to invalid swap_info_struct. Excessive log
> >> printing can fill up the prioritized log space, leading to the purging of
> >> originally valid logs and hindering problem troubleshooting. To make this
> >> more robust, kill this task.
> > 
> > this seems like a very bad way to fix this problem
> 
> Sure, It's a bad way to fix this. Just a proper way to make it more robust?
> Since it will produce lots of invalid and same log?

We have a mechanism to prevent flooding the log: <linux/ratelimit.h>.
If you grep for 'ratelimit' in include, you'll see a number of
convenience functions exist; not sure whether you'll need to use the raw
ratelilmit stuff, or if you can just use one of the prepared ones.