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| author | Gregory Price <gourry@gourry.net> | 2024-10-25 10:17:24 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-11-08 16:28:26 +0100 |
| commit | 1a49b96c51063d38be296a0c1537928a06f02d6e (patch) | |
| tree | 2717059e72dac7dfc83b785deba3bcca1e7cf97e /mm | |
| parent | 003d2996964c03dfd34860500428f4cdf1f5879e (diff) | |
| download | linux-1a49b96c51063d38be296a0c1537928a06f02d6e.tar.gz linux-1a49b96c51063d38be296a0c1537928a06f02d6e.tar.bz2 linux-1a49b96c51063d38be296a0c1537928a06f02d6e.zip | |
vmscan,migrate: fix page count imbalance on node stats when demoting pages
[ Upstream commit 35e41024c4c2b02ef8207f61b9004f6956cf037b ]
When numa balancing is enabled with demotion, vmscan will call
migrate_pages when shrinking LRUs. migrate_pages will decrement the
the node's isolated page count, leading to an imbalanced count when
invoked from (MG)LRU code.
The result is dmesg output like such:
$ cat /proc/sys/vm/stat_refresh
[77383.088417] vmstat_refresh: nr_isolated_anon -103212
[77383.088417] vmstat_refresh: nr_isolated_file -899642
This negative value may impact compaction and reclaim throttling.
The following path produces the decrement:
shrink_folio_list
demote_folio_list
migrate_pages
migrate_pages_batch
migrate_folio_move
migrate_folio_done
mod_node_page_state(-ve) <- decrement
This path happens for SUCCESSFUL migrations, not failures. Typically
callers to migrate_pages are required to handle putback/accounting for
failures, but this is already handled in the shrink code.
When accounting for migrations, instead do not decrement the count when
the migration reason is MR_DEMOTION. As of v6.11, this demotion logic
is the only source of MR_DEMOTION.
Link: https://lkml.kernel.org/r/20241025141724.17927-1-gourry@gourry.net
Fixes: 26aa2d199d6f ("mm/migrate: demote pages during reclaim")
Signed-off-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Wei Xu <weixugc@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/migrate.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 5d7d39b1c069..c5ed8caf6a40 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1093,7 +1093,7 @@ static void migrate_folio_done(struct folio *src, * not accounted to NR_ISOLATED_*. They can be recognized * as __PageMovable */ - if (likely(!__folio_test_movable(src))) + if (likely(!__folio_test_movable(src)) && reason != MR_DEMOTION) mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON + folio_is_file_lru(src), -folio_nr_pages(src)); |