--- drivers/char/mem.c

+++ drivers/char/mem.c

@@ -837,10 +837,11 @@ static const struct file_operations zero

/*

* capabilities for /dev/zero

* - permits private mappings, "copies" are taken of the source of zeros

+ * - no writeback happens

*/

static struct backing_dev_info zero_bdi = {

.name = "char/mem",

- .capabilities = BDI_CAP_MAP_COPY,

+ .capabilities = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK,

};

static const struct file_operations full_fops = {