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Message-ID: <20240102175338.62012-9-ryncsn@gmail.com>
Date: Wed, 3 Jan 2024 01:53:37 +0800
From: Kairui Song <ryncsn@...il.com>
To: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Chris Li <chrisl@...nel.org>,
"Huang, Ying" <ying.huang@...el.com>,
Hugh Dickins <hughd@...gle.com>,
Johannes Weiner <hannes@...xchg.org>,
Matthew Wilcox <willy@...radead.org>,
Michal Hocko <mhocko@...e.com>,
Yosry Ahmed <yosryahmed@...gle.com>,
David Hildenbrand <david@...hat.com>,
linux-kernel@...r.kernel.org,
Kairui Song <kasong@...cent.com>
Subject: [PATCH v2 8/9] mm/swap: introduce a helper for swapin without vmfault
From: Kairui Song <kasong@...cent.com>
There are two places where swapin is not caused by direct anon page fault:
- shmem swapin, invoked indirectly through shmem mapping
- swapoff
They used to construct a pseudo vmfault struct for swapin function.
Shmem has dropped the pseudo vmfault recently in commit ddc1a5cbc05d
("mempolicy: alloc_pages_mpol() for NUMA policy without vma"). Swapoff
path is still using one.
Introduce a helper for them both, this help save stack usage for swapoff
path, and help apply a unified swapin cache and readahead policy check.
Due to missing vmfault info, the caller have to pass in mempolicy
explicitly, make it different from swapin_entry and name it
swapin_entry_mpol.
This commit convert swapoff to use this helper, follow-up commits will
convert shmem to use it too.
Signed-off-by: Kairui Song <kasong@...cent.com>
---
mm/swap.h | 9 +++++++++
mm/swap_state.c | 40 ++++++++++++++++++++++++++++++++--------
mm/swapfile.c | 15 ++++++---------
3 files changed, 47 insertions(+), 17 deletions(-)
diff --git a/mm/swap.h b/mm/swap.h
index 9180411afcfe..8f790a67b948 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -73,6 +73,9 @@ struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
struct mempolicy *mpol, pgoff_t ilx);
struct folio *swapin_entry(swp_entry_t entry, gfp_t flag,
struct vm_fault *vmf, enum swap_cache_result *result);
+struct folio *swapin_entry_mpol(swp_entry_t entry, gfp_t gfp_mask,
+ struct mempolicy *mpol, pgoff_t ilx,
+ enum swap_cache_result *result);
static inline unsigned int folio_swap_flags(struct folio *folio)
{
@@ -109,6 +112,12 @@ static inline struct folio *swapin_entry(swp_entry_t swp, gfp_t gfp_mask,
return NULL;
}
+static inline struct page *swapin_entry_mpol(swp_entry_t entry, gfp_t gfp_mask,
+ struct mempolicy *mpol, pgoff_t ilx, enum swap_cache_result *result)
+{
+ return NULL;
+}
+
static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
{
return 0;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 21badd4f0fc7..3edf4b63158d 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -880,14 +880,13 @@ static struct folio *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask,
* in.
*/
static struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask,
- struct vm_fault *vmf, void *shadow)
+ struct mempolicy *mpol, pgoff_t ilx,
+ void *shadow)
{
- struct vm_area_struct *vma = vmf->vma;
struct folio *folio;
- /* skip swapcache */
- folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
- vma, vmf->address, false);
+ folio = (struct folio *)alloc_pages_mpol(gfp_mask, 0,
+ mpol, ilx, numa_node_id());
if (folio) {
if (mem_cgroup_swapin_charge_folio(folio, NULL,
GFP_KERNEL, entry)) {
@@ -943,18 +942,18 @@ struct folio *swapin_entry(swp_entry_t entry, gfp_t gfp_mask,
goto done;
}
+ mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx);
if (swap_use_no_readahead(swp_swap_info(entry), entry)) {
- folio = swapin_direct(entry, gfp_mask, vmf, shadow);
+ folio = swapin_direct(entry, gfp_mask, mpol, ilx, shadow);
cache_result = SWAP_CACHE_BYPASS;
} else {
- mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx);
if (swap_use_vma_readahead())
folio = swap_vma_readahead(entry, gfp_mask, mpol, ilx, vmf);
else
folio = swap_cluster_readahead(entry, gfp_mask, mpol, ilx);
- mpol_cond_put(mpol);
cache_result = SWAP_CACHE_MISS;
}
+ mpol_cond_put(mpol);
done:
if (result)
*result = cache_result;
@@ -962,6 +961,31 @@ struct folio *swapin_entry(swp_entry_t entry, gfp_t gfp_mask,
return folio;
}
+struct folio *swapin_entry_mpol(swp_entry_t entry, gfp_t gfp_mask,
+ struct mempolicy *mpol, pgoff_t ilx,
+ enum swap_cache_result *result)
+{
+ enum swap_cache_result cache_result;
+ void *shadow = NULL;
+ struct folio *folio;
+
+ folio = swap_cache_get_folio(entry, NULL, 0, &shadow);
+ if (folio) {
+ cache_result = SWAP_CACHE_HIT;
+ } else if (swap_use_no_readahead(swp_swap_info(entry), entry)) {
+ folio = swapin_direct(entry, gfp_mask, mpol, ilx, shadow);
+ cache_result = SWAP_CACHE_BYPASS;
+ } else {
+ folio = swap_cluster_readahead(entry, gfp_mask, mpol, ilx);
+ cache_result = SWAP_CACHE_MISS;
+ }
+
+ if (result)
+ *result = cache_result;
+
+ return folio;
+}
+
#ifdef CONFIG_SYSFS
static ssize_t vma_ra_enabled_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 5aa44de11edc..2f77bf143af8 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1840,18 +1840,13 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
do {
struct folio *folio;
unsigned long offset;
+ struct mempolicy *mpol;
unsigned char swp_count;
swp_entry_t entry;
+ pgoff_t ilx;
int ret;
pte_t ptent;
- struct vm_fault vmf = {
- .vma = vma,
- .address = addr,
- .real_address = addr,
- .pmd = pmd,
- };
-
if (!pte++) {
pte = pte_offset_map(pmd, addr);
if (!pte)
@@ -1871,8 +1866,10 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
pte_unmap(pte);
pte = NULL;
- folio = swapin_entry(entry, GFP_HIGHUSER_MOVABLE,
- &vmf, NULL);
+ mpol = get_vma_policy(vma, addr, 0, &ilx);
+ folio = swapin_entry_mpol(entry, GFP_HIGHUSER_MOVABLE,
+ mpol, ilx, NULL);
+ mpol_cond_put(mpol);
if (!folio) {
/*
* The entry could have been freed, and will not
--
2.43.0
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