From: Liam Mark <lmark@xxxxxxxxxxxxxx> Subject: 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@xxxxxxxxxx Signed-off-by: Liam Mark <lmark@xxxxxxxxxxxxxx> Signed-off-by: Georgi Djakov <georgi.djakov@xxxxxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory_hotplug.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) --- a/mm/memory_hotplug.c~mm-memory_hotplug-rate-limit-page-migration-warnings +++ a/mm/memory_hotplug.c @@ -1406,6 +1406,8 @@ do_migrate_range(unsigned long start_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 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)&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); } _
