On 05.08.21 21:02, Zi Yan wrote:
From: Zi Yan <ziy@xxxxxxxxxx>
It keeps the existing behavior when MAX_ORDER grows beyond a section
size.
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
drivers/virtio/virtio_mem.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 19036922f7ef..bab5a81fa796 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -1105,11 +1105,11 @@ static void virtio_mem_clear_fake_offline(unsigned long pfn,
*/
static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
{
- const unsigned long max_nr_pages = MAX_ORDER_NR_PAGES;
+ const unsigned long max_nr_pages = PAGES_PER_SECTION;
unsigned long i;
/*
- * We are always called at least with MAX_ORDER_NR_PAGES
+ * We are always called at least with PAGES_PER_SECTION
* granularity/alignment (e.g., the way subblocks work). All pages
* inside such a block are alike.
*/
@@ -1125,7 +1125,7 @@ static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
if (PageDirty(page)) {
virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
false);
- generic_online_page(page, MAX_ORDER - 1);
+ generic_online_page(page, PAGES_PER_SECTION - 1);
} else {
virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
true);
@@ -1228,7 +1228,7 @@ static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
if (vm->in_sbm) {
/*
* We exploit here that subblocks have at least
- * MAX_ORDER_NR_PAGES size/alignment - so we cannot
+ * PAGES_PER_SECTION size/alignment - so we cannot
* cross subblocks within one call.
*/
id = virtio_mem_phys_to_mb_id(addr);
@@ -2438,14 +2438,14 @@ static int virtio_mem_init(struct virtio_mem *vm)
VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD);
/*
- * We want subblocks to span at least MAX_ORDER_NR_PAGES and
+ * We want subblocks to span at least PAGES_PER_SECTION and
* pageblock_nr_pages pages. This:
* - Simplifies our page onlining code (virtio_mem_online_page_cb)
* and fake page onlining code (virtio_mem_fake_online).
* - Is required for now for alloc_contig_range() to work reliably -
* it doesn't properly handle smaller granularity on ZONE_NORMAL.
*/
- sb_size = max_t(uint64_t, MAX_ORDER_NR_PAGES,
+ sb_size = max_t(uint64_t, PAGES_PER_SECTION,
pageblock_nr_pages) * PAGE_SIZE;
sb_size = max_t(uint64_t, vm->device_block_size, sb_size);
This is very much completely broken and destroys most of the purpose of
virtio-mem. It even is broken once MAX_ORDER would exceed a single
memory section I think.
Whatever you do, keep virtio-mem working *as is* unless someone
explicitly sets MAX_ORDER on the command line to something bigger.
virtio-mem will require some minor adjustments once MAX_ORDER_NR_PAGES
would exceed the memory section size -- the functionality will, however,
be heavily degraded once you increase MAX_ORDER_NR_PAGES in any way
(again, which is fine if it's explicitly done by an admin on the command
line).
As mentioned somewhere else already, we'll have to tackle
alloc_contig_range() to properly deal with pageblock_order granularity,
then we can rework virtio-mem code to be based on that instead of
MAX_ORDER - 1.
--
Thanks,
David / dhildenb
