On Mon, 28 Oct 2024 14:13:26 +0000 Lorenzo Stoakes [off-list ref] wrote:

Userland library functions such as allocators and threading implementations
often require regions of memory to act as 'guard pages' - mappings which,
when accessed, result in a fatal signal being sent to the accessing
process.

The current means by which these are implemented is via a PROT_NONE mmap()
mapping, which provides the required semantics however incur an overhead of
a VMA for each such region.

With a great many processes and threads, this can rapidly add up and incur
a significant memory penalty. It also has the added problem of preventing
merges that might otherwise be permitted.

This series takes a different approach - an idea suggested by Vlasimil
Babka (and before him David Hildenbrand and Jann Horn - perhaps more - the

Nit.  s/Vlasimil/Vlastimil/ ;)


Thanks,
SJ

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