From: David Hildenbrand <david@xxxxxxxxxx> Subject: mm/page_alloc: drop pr_info_ratelimited() in alloc_contig_range() The information that some PFNs are busy is: a) not helpful for ordinary users: we don't even know *who* called alloc_contig_range(). This is certainly not worth a pr_info.*(). b) not really helpful for debugging: we don't have any details *why* these PFNs are busy, and that is what we usually care about. c) not complete: there are other cases where we fail alloc_contig_range() using different paths that are not getting recorded. For example, we reach this path once we succeeded in isolating pageblocks, but failed to migrate some pages - which can happen easily on ZONE_NORMAL (i.e., has_unmovable_pages() is racy) but also on ZONE_MOVABLE i.e., we would have to retry longer to migrate). For example via virtio-mem when unplugging memory, we can create quite some noise (especially with ZONE_NORMAL) that is not of interest to users - it's expected that some allocations may fail as memory is busy. Let's just drop that pr_info_ratelimit() and rather implement a dynamic debugging mechanism in the future that can give us a better reason why alloc_contig_range() failed on specific pages. Link: https://lkml.kernel.org/r/20210301150945.77012-1-david@xxxxxxxxxx Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx> Acked-by: Minchan Kim <minchan@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 2 -- 1 file changed, 2 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-drop-pr_info_ratelimited-in-alloc_contig_range +++ a/mm/page_alloc.c @@ -8676,8 +8676,6 @@ int alloc_contig_range(unsigned long sta /* Make sure the range is really isolated. */ if (test_pages_isolated(outer_start, end, 0)) { - pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n", - __func__, outer_start, end); ret = -EBUSY; goto done; } _
