Where is the decision to allocate a swap table made?

Where is the decision to allocate a swap table made?

Posted Feb 3, 2026 16:04 UTC (Tue) by farnz (subscriber, #17727)
In reply to: Dynamic allocation by daroc
Parent article: Modernizing swapping: introducing the swap table

Do you know where the decision to allocate the table is made?

I'm wondering if the kernel is able to promise that it starts swapping (if there's swap configured) before it's down to its last clean or free page - so that it never actually gets into the situation where it can't allocate a page of physical memory to allow it to free up more by swapping, because in the worst case, it can do the file-backed page dance you describe.

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Where is the decision to allocate a swap table made?

Posted Feb 3, 2026 17:13 UTC (Tue) by corbet (editor, #1) [Link]

The kernel will start reclaim long before it gets to that last free page. There are watermark levels that it tries to never go below.