[PATCH v1 06/12] powerpc/pseries: CMM: Rip out memory isolate notifier

David Hildenbrand
2019-10-31T14:30:27Z

The memory isolate notifier was added to allow to offline memory blocks
that contain inflated/"loaned" pages. We can achieve the same using the
balloon compaction framework.

Get rid of the memory isolate notifier. Also, we can get rid of
cmm_mem_going_offline(), as we will never reach that code path now when
we have allocated memory in the balloon (allocated pages are unmovable and
will no longer be special-cased using the memory isolation notifier).

Leave the memory notifier in place, so we can still back off in case
memory gets offlined.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Richard Fontana <rfontana@redhat.com>
Cc: Allison Randal <allison@lohutok.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arun KS <arunks@codeaurora.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/powerpc/platforms/pseries/cmm.c | 97 +---------------------------
1 file changed, 1 insertion(+), 96 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index f82c468ca2c4..29416b621189 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -38,12 +38,8 @@
#define CMM_MIN_MEM_MB 256
#define KB2PAGES(_p) ((_p)>>(PAGE_SHIFT-10))
#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
-/*
- * The priority level tries to ensure that this notifier is called as
- * late as possible to reduce thrashing in the shared memory pool.
- */
+
#define CMM_MEM_HOTPLUG_PRI 1
-#define CMM_MEM_ISOLATE_PRI 15

static unsigned int delay = CMM_DEFAULT_DELAY;
static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY;
@@ -446,90 +442,6 @@ static struct notifier_block cmm_reboot_nb = {
.notifier_call = cmm_reboot_notifier,
};

-/**
- * cmm_count_pages - Count the number of pages loaned in a particular range.
- *
- * @arg: memory_isolate_notify structure with address range and count
- *
- * Return value:
- * 0 on success
- **/
-static unsigned long cmm_count_pages(void *arg)
-{
- struct memory_isolate_notify *marg = arg;
- struct page *page;
-
- spin_lock(&cmm_lock);
- list_for_each_entry(page, &cmm_page_list, lru) {
- if (page_to_pfn(page) >= marg->start_pfn &&
- page_to_pfn(page) < marg->start_pfn + marg->nr_pages)
- marg->pages_found++;
- }
- spin_unlock(&cmm_lock);
- return 0;
-}
-
-/**
- * cmm_memory_isolate_cb - Handle memory isolation notifier calls
- * @self: notifier block struct
- * @action: action to take
- * @arg: struct memory_isolate_notify data for handler
- *
- * Return value:
- * NOTIFY_OK or notifier error based on subfunction return value
- **/
-static int cmm_memory_isolate_cb(struct notifier_block *self,
- unsigned long action, void *arg)
-{
- int ret = 0;
-
- if (action == MEM_ISOLATE_COUNT)
- ret = cmm_count_pages(arg);
-
- return notifier_from_errno(ret);
-}
-
-static struct notifier_block cmm_mem_isolate_nb = {
- .notifier_call = cmm_memory_isolate_cb,
- .priority = CMM_MEM_ISOLATE_PRI
-};
-
-/**
- * cmm_mem_going_offline - Unloan pages where memory is to be removed
- * @arg: memory_notify structure with page range to be offlined
- *
- * Return value:
- * 0 on success
- **/
-static int cmm_mem_going_offline(void *arg)
-{
- struct memory_notify *marg = arg;
- struct page *page, *tmp;
- unsigned long freed = 0;
-
- cmm_dbg("Memory going offline, searching PFN 0x%lx (%ld pages).\n",
- marg->start_pfn, marg->nr_pages);
- spin_lock(&cmm_lock);
-
- /* Search the page list for pages in the range to be offlined */
- list_for_each_entry_safe(page, tmp, &cmm_page_list, lru) {
- if (page_to_pfn(page) < marg->start_pfn ||
- page_to_pfn(page) >= marg->start_pfn + marg->nr_pages)
- continue;
- plpar_page_set_active(page);
- list_del(&page->lru);
- adjust_managed_page_count(page, 1);
- __free_page(page);
- freed++;
- loaned_pages--;
- }
-
- spin_unlock(&cmm_lock);
- cmm_dbg("Released %ld pages in the search range.\n", freed);
-
- return 0;
-}
-
/**
* cmm_memory_cb - Handle memory hotplug notifier calls
* @self: notifier block struct
@@ -549,7 +461,6 @@ static int cmm_memory_cb(struct notifier_block *self,
case MEM_GOING_OFFLINE:
mutex_lock(&hotplug_mutex);
hotplug_occurred = 1;
- ret = cmm_mem_going_offline(arg);
break;
case MEM_OFFLINE:
case MEM_CANCEL_OFFLINE:
@@ -596,10 +507,6 @@ static int cmm_init(void)
if (rc)
goto out_unregister_notifier;

- rc = register_memory_isolate_notifier(&cmm_mem_isolate_nb);
- if (rc)
- goto out_unregister_notifier;
-
if (cmm_disabled)
return 0;

@@ -612,7 +519,6 @@ static int cmm_init(void)
return 0;
out_unregister_notifier:
unregister_memory_notifier(&cmm_mem_nb);
- unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
cmm_unregister_sysfs(&cmm_dev);
out_reboot_notifier:
unregister_reboot_notifier(&cmm_reboot_nb);
@@ -634,7 +540,6 @@ static void cmm_exit(void)
unregister_oom_notifier(&cmm_oom_nb);
unregister_reboot_notifier(&cmm_reboot_nb);
unregister_memory_notifier(&cmm_mem_nb);
- unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
cmm_free_pages(loaned_pages);
cmm_unregister_sysfs(&cmm_dev);
}
--
2.21.0