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.
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/page_alloc.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 519a60d5b6f7..efb924fb13e8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8647,8 +8647,6 @@ int alloc_contig_range(unsigned long start, unsigned long end,
/* 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;
}
--
2.29.2
