Corner case

Posted Nov 12, 2025 17:42 UTC (Wed) by farnz (subscriber, #17727)
In reply to: Corner case by abatters
Parent article: The intersection of unstable pages and direct I/O

My understanding is that your corner case as shown would not trigger conflict detection, because the buffer is not changed by the write. The problem would come with two reads to different parts of the same page (at sector alignment, on a system where sectors are smaller than pages), where page granularity would detect two places changing the same page.

This is a fixable problem if it's a common false positive - once page granularity detection says "two direct I/O reads to same page", you'd add in a check for overlap there.