lib/test_hmm.c: remove unused dmirror_zero_page

The variable dmirror_zero_page is unused in the HMM self test driver which
was probably intended to demonstrate how a driver could use
migrate_vma_setup() to share a single read-only device private zero page
similar to how the CPU does.  However, this isn't needed for the self
tests so remove it.

Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jerome Glisse <jglisse@redhat.com>
Link: https://lkml.kernel.org/r/20200914213801.16520-1-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index c710b4c5714d0a58dc8a4843cbcfd33e2c112dd8..e151a7f105193a17d7a70fd60b5e4e200265ef02 100644 (file)
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -36,7 +36,6 @@
 static const struct dev_pagemap_ops dmirror_devmem_ops;
 static const struct mmu_interval_notifier_ops dmirror_min_ops;
 static dev_t dmirror_dev;
-static struct page *dmirror_zero_page;
 
 struct dmirror_device;
 
@@ -1127,17 +1126,6 @@ static int __init hmm_dmirror_init(void)
                        goto err_chrdev;
        }
 
-       /*
-        * Allocate a zero page to simulate a reserved page of device private
-        * memory which is always zero. The zero_pfn page isn't used just to
-        * make the code here simpler (i.e., we need a struct page for it).
-        */
-       dmirror_zero_page = alloc_page(GFP_HIGHUSER | __GFP_ZERO);
-       if (!dmirror_zero_page) {
-               ret = -ENOMEM;
-               goto err_chrdev;
-       }
-
        pr_info("HMM test module loaded. This is only for testing HMM.\n");
        return 0;
 
@@ -1153,8 +1141,6 @@ static void __exit hmm_dmirror_exit(void)
 {
        int id;
 
-       if (dmirror_zero_page)
-               __free_page(dmirror_zero_page);
        for (id = 0; id < DMIRROR_NDEVICES; id++)
                dmirror_device_remove(dmirror_devices + id);
        unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);