Gleb Natapov <[email protected]> writes:
> If application does mlockall(MCL_FUTURE) it is no longer possible to
> mmap file bigger than main memory or allocate big area of anonymous
> memory. Sometimes it is desirable to lock everything related to program
> execution into memory, but still be able to mmap big file or allocate
> huge amount of memory and allow OS to swap them on demand. MAP_UNLOCKED
> allows to do that.
>
> Signed-off-by: Gleb Natapov <[email protected]>
<snip>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 73f5e4b..ecc4471 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -985,6 +985,9 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned
> long addr,
> if (!can_do_mlock())
> return -EPERM;
>
> + if (flags & MAP_UNLOCKED)
> + vm_flags &= ~VM_LOCKED;
> +
> /* mlock MCL_FUTURE? */
> if (vm_flags & VM_LOCKED) {
> unsigned long locked, lock_limit;
So, if I read it correctly, it is perfectly legal to set
both MAP_LOCKED and MAP_UNLOCKED at the same time? While
the behavior is still same as only setting MAP_UNLOCKED.
Is this what we expect?
Regards.
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