Re: Should mmap MAP_LOCKED fail if mm_poppulate fails?

[Michal Hocko <mhocko@suse.cz>]

Hi,
it seems that the initial email got lost (or ignored). I would like to
revive it again. I've cooked up a potential fix to this issue which will
follow as a reply to this email.

The first patch is dumb and straightforward. It should be safe as is and
also good without the follow up 2 patches which try to handle potential
allocation failures in the do_munmap path more gracefully. As we still
do not fail small allocations even the first patch could be simplified
a bit and the retry loop replaced by a BUG_ON right away. But I felt this
would better be done robust.

An obvious alternative would be patching the man pages to mention the
subtle difference between mlock and MAP_LOCKED semantic. I have checked
debian code search and it shown some applications relying on MAP_LOCKED
but I have no idea whether they really require the mlock all-or-nothing
fault in semantic.

Any thoughts, ideas?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>