From 51f43d5d82ed2ba3f9a3f9a2390c52f28e42af32 Mon Sep 17 00:00:00 2001 From: David Wang <00107082@163.com> Date: Fri, 29 Nov 2024 10:52:13 +0800 Subject: mm/codetag: swap tags when migrate pages Current solution to adjust codetag references during page migration is done in 3 steps: 1. sets the codetag reference of the old page as empty (not pointing to any codetag); 2. subtracts counters of the new page to compensate for its own allocation; 3. sets codetag reference of the new page to point to the codetag of the old page. This does not work if CONFIG_MEM_ALLOC_PROFILING_DEBUG=n because set_codetag_empty() becomes NOOP. Instead, let's simply swap codetag references so that the new page is referencing the old codetag and the old page is referencing the new codetag. This way accounting stays valid and the logic makes more sense. Link: https://lkml.kernel.org/r/20241129025213.34836-1-00107082@163.com Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") Signed-off-by: David Wang <00107082@163.com> Closes: https://lore.kernel.org/lkml/20241124074318.399027-1-00107082@163.com/ Acked-by: Suren Baghdasaryan Suggested-by: Suren Baghdasaryan Acked-by: Yu Zhao Cc: Kent Overstreet Signed-off-by: Andrew Morton --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/migrate.c b/mm/migrate.c index 2ce6b4b814df..cc68583c86f9 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -745,7 +745,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio) folio_set_readahead(newfolio); folio_copy_owner(newfolio, folio); - pgalloc_tag_copy(newfolio, folio); + pgalloc_tag_swap(newfolio, folio); mem_cgroup_migrate(folio, newfolio); } -- cgit v1.2.3