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

On Mon 22-02-21 14:22:37, David Hildenbrand wrote:

quoted

quoted

Exactly. But for hugetlbfs/shmem ("!RAM-backed files") this is not what we
want.

OK, then I must have misread your requirements. Maybe I just got lost in
all the combinations you have listed.

Another special case could be dax/pmem I think. You might want to fault it
in readable/writable but not perform an actual read/write unless really
required.

QEMU phrases this as "don't cause wear on the storage backing".

Sorry for being dense here but I still do not follow. If you do not want
to read then what do you want to populate from? Only map if it is in the
page cache?
-- 
Michal Hocko
SUSE Labs