The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 3a06696305e757f652dd0dcf4dfa2272eda39434 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025041714-coeditor-trance-46cb@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3a06696305e757f652dd0dcf4dfa2272eda39434 Mon Sep 17 00:00:00 2001 From: Usama Arif usamaarif642@gmail.com Date: Fri, 7 Feb 2025 13:20:32 -0800 Subject: [PATCH] mm/damon/ops: have damon_get_folio return folio even for tail pages

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

diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c index 86a50e8fbc80..0db1fc70c84d 100644 --- a/mm/damon/ops-common.c +++ b/mm/damon/ops-common.c @@ -26,7 +26,7 @@ struct folio *damon_get_folio(unsigned long pfn) struct page *page = pfn_to_online_page(pfn); struct folio *folio;

- if (!page || PageTail(page)) + if (!page) return NULL;

folio = page_folio(page); diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c index 1a89920efce9..2ac19ebc7076 100644 --- a/mm/damon/paddr.c +++ b/mm/damon/paddr.c @@ -277,11 +277,14 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s, 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; @@ -297,6 +300,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s, else list_add(&folio->lru, &folio_list); put_folio: + addr += folio_size(folio); folio_put(folio); } if (install_young_filter) @@ -312,11 +316,14 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate( { 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; @@ -329,6 +336,7 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate( folio_deactivate(folio); applied += folio_nr_pages(folio); put_folio: + addr += folio_size(folio); folio_put(folio); } return applied * PAGE_SIZE; @@ -475,11 +483,14 @@ static unsigned long damon_pa_migrate(struct damon_region *r, struct damos *s, 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; @@ -490,6 +501,7 @@ static unsigned long damon_pa_migrate(struct damon_region *r, struct damos *s, 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);