mm/mlock.c: document scary-looking stack expansion mlock chain
authorJohannes Weiner <hannes@cmpxchg.org>
Sat, 23 Feb 2013 00:35:20 +0000 (16:35 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sun, 24 Feb 2013 01:50:20 +0000 (17:50 -0800)
commit4805b02e90187c68d8f4e3305c3482b797e35809
tree65d574e7ee8068597f59b712417b6ecf700d1a49
parente3790144c9091631a18564aa64db8a971da02c41
mm/mlock.c: document scary-looking stack expansion mlock chain

The fact that mlock calls get_user_pages, and get_user_pages might call
mlock when expanding a stack looks like a potential recursion.

However, mlock makes sure the requested range is already contained
within a vma, so no stack expansion will actually happen from mlock.

Should this ever change: the stack expansion mlocks only the newly
expanded range and so will not result in recursive expansion.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/mlock.c