userfaultfd: non-cooperative: release all ctx in dup_userfaultfd_complete

Don't stop running dup_fctx() even if userfaultfd_event_wait_completion
fails as it has to run userfaultfd_ctx_put on all ctx to pair against
the userfaultfd_ctx_get that was run on all fctx->orig in
dup_userfaultfd.

Link: http://lkml.kernel.org/r/20170224181957.19736-4-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 668bbbd..dd48052 100644 (file)
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -527,16 +527,12 @@ out:
        return ret;
 }
 
-static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
-                                            struct userfaultfd_wait_queue *ewq)
+static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
+                                             struct userfaultfd_wait_queue *ewq)
 {
-       int ret;
-
-       ret = -1;
        if (WARN_ON_ONCE(current->flags & PF_EXITING))
                goto out;
 
-       ret = 0;
        ewq->ctx = ctx;
        init_waitqueue_entry(&ewq->wq, current);
 
@@ -552,7 +548,6 @@ static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
                        break;
                if (ACCESS_ONCE(ctx->released) ||
                    fatal_signal_pending(current)) {
-                       ret = -1;
                        __remove_wait_queue(&ctx->event_wqh, &ewq->wq);
                        break;
                }
@@ -573,7 +568,6 @@ static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
         */
 out:
        userfaultfd_ctx_put(ctx);
-       return ret;
 }
 
 static void userfaultfd_event_complete(struct userfaultfd_ctx *ctx,
@@ -631,7 +625,7 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
        return 0;
 }
 
-static int dup_fctx(struct userfaultfd_fork_ctx *fctx)
+static void dup_fctx(struct userfaultfd_fork_ctx *fctx)
 {
        struct userfaultfd_ctx *ctx = fctx->orig;
        struct userfaultfd_wait_queue ewq;
@@ -641,17 +635,15 @@ static int dup_fctx(struct userfaultfd_fork_ctx *fctx)
        ewq.msg.event = UFFD_EVENT_FORK;
        ewq.msg.arg.reserved.reserved1 = (unsigned long)fctx->new;
 
-       return userfaultfd_event_wait_completion(ctx, &ewq);
+       userfaultfd_event_wait_completion(ctx, &ewq);
 }
 
 void dup_userfaultfd_complete(struct list_head *fcs)
 {
-       int ret = 0;
        struct userfaultfd_fork_ctx *fctx, *n;
 
        list_for_each_entry_safe(fctx, n, fcs, list) {
-               if (!ret)
-                       ret = dup_fctx(fctx);
+               dup_fctx(fctx);
                list_del(&fctx->list);
                kfree(fctx);
        }