[PATCH v2 16/26] mm/fbatch: remove lru_cache_disable() from NUMA folio migration
From: Hugh Dickins <hughd@google.com>
Date: 2026-09-09 10:14:20
Also in:
linux-block, linux-fsdevel, lkml
Subsystem:
memory management, memory management - memory policy and migration, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Remove lru_cache_disable() from mbind(MOVE), migrate_pages and move_pages
syscall handling. They do not now benefit from lru_add_drain_all() first;
they gain little benefit from invalidating buffer head LRUs first, since
5.0 commit 80409c65e2c6 ("mm: migrate: make buffer_migrate_page_norefs()
actually succeed"); and it's a shame that (even without CAP_SYS_NICE)
they can prevent concurrent tasks from enjoying the use of those caches.
Signed-off-by: Hugh Dickins <hughd@google.com>
---
mm/mempolicy.c | 7 -------
mm/migrate.c | 3 ---
2 files changed, 10 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 79053ece02cd..f4d9b5580632 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c@@ -1343,8 +1343,6 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from, long err = 0; nodemask_t tmp; - lru_cache_disable(); - /* * Find a 'source' bit set in 'tmp' whose corresponding 'dest' * bit in 'to' is not also set in 'tmp'. Clear the found 'source'
@@ -1425,7 +1423,6 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from, break; } - lru_cache_enable(); if (err < 0) return err; return (nr_failed < INT_MAX) ? nr_failed : INT_MAX;
@@ -1530,8 +1527,6 @@ static long do_mbind(unsigned long start, unsigned long len, if (!new) flags |= MPOL_MF_DISCONTIG_OK; - if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) - lru_cache_disable(); { NODEMASK_SCRATCH(scratch); if (scratch) {
@@ -1626,8 +1621,6 @@ static long do_mbind(unsigned long start, unsigned long len, putback_movable_pages(&pagelist); mpol_out: mpol_put(new); - if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) - lru_cache_enable(); return err; }
diff --git a/mm/migrate.c b/mm/migrate.c
index 364015cbef33..1d2085529cd0 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c@@ -2359,8 +2359,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, int start, i; int err = 0, err1; - lru_cache_disable(); - for (i = start = 0; i < nr_pages; i++) { const void __user *p; int node;
@@ -2439,7 +2437,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, if (err >= 0) err = err1; out: - lru_cache_enable(); return err; }
--
2.51.0