Re: [PATCH RFC] mm/madvise: introduce MADV_POPULATE to prefault/prealloc memory

Rolf Eike Beer
2021-02-18T13:06:05Z

>> Let's introduce MADV_POPULATE with the following semantics
>> 1. MADV_POPULATED does not work on PROT_NONE and special VMAs. It
>> works
>> on everything else.
>> 2. Errors during MADV_POPULATED (especially OOM) are reported. If we
>> hit
>> hardware errors on pages, ignore them - nothing we really can or
>> should do.
>> 3. On errors during MADV_POPULATED, some memory might have been
>> populated. Callers have to clean up if they care.
>> 4. Concurrent changes to the virtual memory layour are tolerated - we
^t
>> process each and every PFN only once, though.
>> 5. If MADV_POPULATE succeeds, all memory in the range can be accessed
>> without SIGBUS. (of course, not if user space changed mappings in
>> the
>> meantime or KSM kicked in on anonymous memory).

You are talking both about MADV_POPULATE and MADV_POPULATED here.

Eike