Re: process 'stuck' at exit.

[Linus Torvalds]

On Tue, Dec 10, 2013 at 1:41 PM, Dave Jones <davej@xxxxxxxxxx> wrote:
>
> http://codemonkey.org.uk/junk/trace

Hmm. Ok, so something is calling [__]get_user_pages_fast() and
put_page() in a loop, but the trace doesn't show what that "something"
is, because it is itself not ever called.

However, that pattern does seem to imply that the loop is in
get_futex_key(), because all the other loops I see seem to be calling
other things as well.

And the __get_user_pages_fast() call implies that it's the THP case
that triggers the "unlikely(PageTail(page))" case. And anyway,
otherwise we'd see lock_page()/unlock_page() too.

So it looks like __get_user_pages_fast() fails, and keeps failing.
Andrea, this is your code, any ideas? Commit a5b338f2b0b1f ("thp:
update futex compound knowledge") to be exact.

                   Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/