futex: fix handling of read-only-mapped hugepages

commit f12d5bfceb7e1f9051563381ec047f7f13956c3c upstream.

The hugepage code had the exact same bug that regular pages had in
commit 7485d0d3758e ("futexes: Remove rw parameter from
get_futex_key()").

The regular page case was fixed by commit 9ea71503a8ed ("futex: Fix
regression with read only mappings"), but the transparent hugepage case
(added in a5b338f2b0b1: "thp: update futex compound knowledge") case
remained broken.

Found by Dave Jones and his trinity tool.

Reported-and-tested-by: Dave Jones <davej@fedoraproject.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/futex.c b/kernel/futex.c
index 49dacfb4574563b61551a436a21a2fc33053e47f..a283b3041072dfc2478b322a100ac4d034b681b3 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -287,7 +287,7 @@ again:
                put_page(page);
                /* serialize against __split_huge_page_splitting() */
                local_irq_disable();
-               if (likely(__get_user_pages_fast(address, 1, 1, &page) == 1)) {
+               if (likely(__get_user_pages_fast(address, 1, !ro, &page) == 1)) {
                        page_head = compound_head(page);
                        /*
                         * page_head is valid pointer but we must pin