mm/memory_hotplug: rate limit page migration warnings

When offlining memory the system can attempt to migrate a lot of pages, if
there are problems with migration this can flood the logs.  Printing all
the data hogs the CPU and cause some RT threads to run for a long time,
which may have some bad consequences.

Rate limit the page migration warnings in order to avoid this.

Link: https://lkml.kernel.org/r/20210505140542.24935-1-georgi.djakov@linaro.org
Signed-off-by: Liam Mark <lmark@codeaurora.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 492560b619998f4827afd988309f92ade519174f..1a9568d90ea7604ccf6dff84027de80dca4afe8c 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1406,6 +1406,8 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
        struct page *page, *head;
        int ret = 0;
        LIST_HEAD(source);
+       static DEFINE_RATELIMIT_STATE(migrate_rs, DEFAULT_RATELIMIT_INTERVAL,
+                                     DEFAULT_RATELIMIT_BURST);
 
        for (pfn = start_pfn; pfn < end_pfn; pfn++) {
                if (!pfn_valid(pfn))
@@ -1452,8 +1454,10 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
                                                    page_is_file_lru(page));
 
                } else {
-                       pr_warn("failed to isolate pfn %lx\n", pfn);
-                       dump_page(page, "isolation failed");
+                       if (__ratelimit(&migrate_rs)) {
+                               pr_warn("failed to isolate pfn %lx\n", pfn);
+                               dump_page(page, "isolation failed");
+                       }
                }
                put_page(page);
        }
@@ -1482,9 +1486,11 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
                        (unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
                if (ret) {
                        list_for_each_entry(page, &source, lru) {
-                               pr_warn("migrating pfn %lx failed ret:%d ",
-                                      page_to_pfn(page), ret);
-                               dump_page(page, "migration failure");
+                               if (__ratelimit(&migrate_rs)) {
+                                       pr_warn("migrating pfn %lx failed ret:%d\n",
+                                               page_to_pfn(page), ret);
+                                       dump_page(page, "migration failure");
+                               }
                        }
                        putback_movable_pages(&source);
                }