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Posted Sep 5, 2022 18:49 UTC (Mon) by corbet (editor, #1)
In reply to: Concurrent page-fault handling with per-VMA locks by developer122
Parent article: Concurrent page-fault handling with per-VMA locks

This is just a guess but ... I would expect that, if a VMA has been entirely idle for long enough for the sequence number to roll over and completely back around, the chances of an access coming at just the right time to cause a false positive are pretty tiny. But if that occurs, the worst that happens is that a fault is handled a bit more slowly that it otherwise would be.

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Posted Oct 12, 2022 16:46 UTC (Wed) by surenb (guest, #114881) [Link]

Mr Corbet is right as usual. The comment in https://lwn.net/ml/linux-kernel/c84136d3-703a-0e57-20ce-5... indicates " Overflow might produce false locked result but it's not critical.". This is because we will simply fallback to taking mmap_lock in the case of the false positive. Per Laurent's comment I'm going to expand this comment to explain the details.


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