UPSTREAM: mm: fix new crash in unmapped_area_topdown()
commit f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89 upstream.
Trinity gets kernel BUG at mm/mmap.c:1963! in about 3 minutes of
mmap testing. That's the VM_BUG_ON(gap_end < gap_start) at the
end of unmapped_area_topdown(). Linus points out how MAP_FIXED
(which does not have to respect our stack guard gap intentions)
could result in gap_end below gap_start there. Fix that, and
the similar case in its alternative, unmapped_area().
BUG=chromium:726072, chromium:724093
TEST=Build and run
Change-Id: Ib30cb5cb70c80f7186caf63f7ac1def7ded76e8b
Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas")
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Debugged-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
(cherry picked from commit 1f2284fac218,
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git)
Reviewed-on: https://chromium-review.googlesource.com/545099
Commit-Ready: Sonny Rao <sonnyrao@chromium.org>
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
(cherry picked from commit 2dd361385e91df1d33e208e35708a9150684ab1f)
Reviewed-on: https://chromium-review.googlesource.com/565521
1 file changed
