aio: don't bother with unmapping when aio_free_ring() is coming from exit_aio()
... since exit_mmap() is coming and it will munmap() everything anyway.
In all other cases aio_free_ring() has ctx->mm == current->mm; moreover,
all other callers of vm_munmap() have mm == current->mm, so this will
allow us to get rid of mm argument of vm_munmap().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/aio.c b/fs/aio.c
index 99bd790..976e33d9 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -92,8 +92,10 @@
for (i=0; i<info->nr_pages; i++)
put_page(info->ring_pages[i]);
- if (info->mmap_size)
+ if (info->mmap_size) {
+ BUG_ON(ctx->mm != current->mm);
vm_munmap(ctx->mm, info->mmap_base, info->mmap_size);
+ }
if (info->ring_pages && info->ring_pages != info->internal_pages)
kfree(info->ring_pages);
@@ -386,6 +388,17 @@
"exit_aio:ioctx still alive: %d %d %d\n",
atomic_read(&ctx->users), ctx->dead,
ctx->reqs_active);
+ /*
+ * We don't need to bother with munmap() here -
+ * exit_mmap(mm) is coming and it'll unmap everything.
+ * Since aio_free_ring() uses non-zero ->mmap_size
+ * as indicator that it needs to unmap the area,
+ * just set it to 0; aio_free_ring() is the only
+ * place that uses ->mmap_size, so it's safe.
+ * That way we get all munmap done to current->mm -
+ * all other callers have ctx->mm == current->mm.
+ */
+ ctx->ring_info.mmap_size = 0;
put_ioctx(ctx);
}
}