[PATCH v6 1/2] mm: add nr argument in mem_cgroup_swapin_uncharge_swap() helper to support large folios

From: Barry Song
Date: Fri Aug 02 2024 - 08:21:17 EST


From: Barry Song <v-songbaohua@xxxxxxxx>

With large folios swap-in, we might need to uncharge multiple entries
all together, add nr argument in mem_cgroup_swapin_uncharge_swap().

For the existing two users, just pass nr=1.

Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
---
include/linux/memcontrol.h | 5 +++--
mm/memcontrol.c | 7 ++++---
mm/memory.c | 2 +-
mm/swap_state.c | 2 +-
4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 1b79760af685..44f7fb7dc0c8 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -682,7 +682,8 @@ int mem_cgroup_hugetlb_try_charge(struct mem_cgroup *memcg, gfp_t gfp,

int mem_cgroup_swapin_charge_folio(struct folio *folio, struct mm_struct *mm,
gfp_t gfp, swp_entry_t entry);
-void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry);
+
+void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);

void __mem_cgroup_uncharge(struct folio *folio);

@@ -1181,7 +1182,7 @@ static inline int mem_cgroup_swapin_charge_folio(struct folio *folio,
return 0;
}

-static inline void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry)
+static inline void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry, unsigned int nr)
{
}

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b889a7fbf382..5d763c234c44 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4572,14 +4572,15 @@ int mem_cgroup_swapin_charge_folio(struct folio *folio, struct mm_struct *mm,

/*
* mem_cgroup_swapin_uncharge_swap - uncharge swap slot
- * @entry: swap entry for which the page is charged
+ * @entry: the first swap entry for which the pages are charged
+ * @nr_pages: number of pages which will be uncharged
*
* Call this function after successfully adding the charged page to swapcache.
*
* Note: This function assumes the page for which swap slot is being uncharged
* is order 0 page.
*/
-void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry)
+void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
{
/*
* Cgroup1's unified memory+swap counter has been charged with the
@@ -4599,7 +4600,7 @@ void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry)
* let's not wait for it. The page already received a
* memory+swap charge, drop the swap entry duplicate.
*/
- mem_cgroup_uncharge_swap(entry, 1);
+ mem_cgroup_uncharge_swap(entry, nr_pages);
}
}

diff --git a/mm/memory.c b/mm/memory.c
index 4c8716cb306c..4cf4902db1ec 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4102,7 +4102,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
ret = VM_FAULT_OOM;
goto out_page;
}
- mem_cgroup_swapin_uncharge_swap(entry);
+ mem_cgroup_swapin_uncharge_swap(entry, 1);

shadow = get_shadow_from_swap_cache(entry);
if (shadow)
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 293ff1afdca4..1159e3225754 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -522,7 +522,7 @@ struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
if (add_to_swap_cache(new_folio, entry, gfp_mask & GFP_RECLAIM_MASK, &shadow))
goto fail_unlock;

- mem_cgroup_swapin_uncharge_swap(entry);
+ mem_cgroup_swapin_uncharge_swap(entry, 1);

if (shadow)
workingset_refault(new_folio, shadow);
--
2.34.1