6.14-stable review patch. If anyone has any objections, please let me know.
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From: Usama Arif usamaarif642@gmail.com
commit 3a06696305e757f652dd0dcf4dfa2272eda39434 upstream.
Patch series "mm/damon/paddr: fix large folios access and schemes handling".
DAMON operations set for physical address space, namely 'paddr', treats tail pages as unaccessed always. It can also apply DAMOS action to a large folio multiple times within single DAMOS' regions walking. As a result, the monitoring output has poor quality and DAMOS works in unexpected ways when large folios are being used. Fix those.
The patches were parts of Usama's hugepage_size DAMOS filter patch series[1]. The first fix has collected from there with a slight commit message change for the subject prefix. The second fix is re-written by SJ and posted as an RFC before this series. The second one also got a slight commit message change for the subject prefix.
[1] https://lore.kernel.org/20250203225604.44742-1-usamaarif642@gmail.com [2] https://lore.kernel.org/20250206231103.38298-1-sj@kernel.org
This patch (of 2):
This effectively adds support for large folios in damon for paddr, as damon_pa_mkold/young won't get a null folio from this function and won't ignore it, hence access will be checked and reported. This also means that larger folios will be considered for different DAMOS actions like pageout, prioritization and migration. As these DAMOS actions will consider larger folios, iterate through the region at folio_size and not PAGE_SIZE intervals. This should not have an affect on vaddr, as damon_young_pmd_entry considers pmd entries.
Link: https://lkml.kernel.org/r/20250207212033.45269-1-sj@kernel.org Link: https://lkml.kernel.org/r/20250207212033.45269-2-sj@kernel.org Fixes: a28397beb55b ("mm/damon: implement primitives for physical address space monitoring") Signed-off-by: Usama Arif usamaarif642@gmail.com Signed-off-by: SeongJae Park sj@kernel.org Reviewed-by: SeongJae Park sj@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/damon/ops-common.c | 2 +- mm/damon/paddr.c | 24 ++++++++++++++++++------ 2 files changed, 19 insertions(+), 7 deletions(-)
--- a/mm/damon/ops-common.c +++ b/mm/damon/ops-common.c @@ -24,7 +24,7 @@ struct folio *damon_get_folio(unsigned l struct page *page = pfn_to_online_page(pfn); struct folio *folio;
- if (!page || PageTail(page)) + if (!page) return NULL;
folio = page_folio(page); --- a/mm/damon/paddr.c +++ b/mm/damon/paddr.c @@ -269,11 +269,14 @@ static unsigned long damon_pa_pageout(st damos_add_filter(s, filter); }
- for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) { + addr = r->ar.start; + while (addr < r->ar.end) { struct folio *folio = damon_get_folio(PHYS_PFN(addr));
- if (!folio) + if (!folio) { + addr += PAGE_SIZE; continue; + }
if (damos_pa_filter_out(s, folio)) goto put_folio; @@ -289,6 +292,7 @@ static unsigned long damon_pa_pageout(st else list_add(&folio->lru, &folio_list); put_folio: + addr += folio_size(folio); folio_put(folio); } if (install_young_filter) @@ -304,11 +308,14 @@ static inline unsigned long damon_pa_mar { unsigned long addr, applied = 0;
- for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) { + addr = r->ar.start; + while (addr < r->ar.end) { struct folio *folio = damon_get_folio(PHYS_PFN(addr));
- if (!folio) + if (!folio) { + addr += PAGE_SIZE; continue; + }
if (damos_pa_filter_out(s, folio)) goto put_folio; @@ -321,6 +328,7 @@ static inline unsigned long damon_pa_mar folio_deactivate(folio); applied += folio_nr_pages(folio); put_folio: + addr += folio_size(folio); folio_put(folio); } return applied * PAGE_SIZE; @@ -467,11 +475,14 @@ static unsigned long damon_pa_migrate(st unsigned long addr, applied; LIST_HEAD(folio_list);
- for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) { + addr = r->ar.start; + while (addr < r->ar.end) { struct folio *folio = damon_get_folio(PHYS_PFN(addr));
- if (!folio) + if (!folio) { + addr += PAGE_SIZE; continue; + }
if (damos_pa_filter_out(s, folio)) goto put_folio; @@ -482,6 +493,7 @@ static unsigned long damon_pa_migrate(st goto put_folio; list_add(&folio->lru, &folio_list); put_folio: + addr += folio_size(folio); folio_put(folio); } applied = damon_pa_migrate_pages(&folio_list, s->target_nid);