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Message-ID: <20231119194740.94101-12-ryncsn@gmail.com>
Date: Mon, 20 Nov 2023 03:47:27 +0800
From: Kairui Song <ryncsn@...il.com>
To: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
"Huang, Ying" <ying.huang@...el.com>,
David Hildenbrand <david@...hat.com>,
Hugh Dickins <hughd@...gle.com>,
Johannes Weiner <hannes@...xchg.org>,
Matthew Wilcox <willy@...radead.org>,
Michal Hocko <mhocko@...e.com>, linux-kernel@...r.kernel.org,
Kairui Song <kasong@...cent.com>
Subject: [PATCH 11/24] mm/swap: also handle swapcache lookup in swapin_readahead
From: Kairui Song <kasong@...cent.com>
No feature change, just prepare for later commits.
Signed-off-by: Kairui Song <kasong@...cent.com>
---
mm/memory.c | 61 +++++++++++++++++++++++--------------------------
mm/swap.h | 10 ++++++--
mm/swap_state.c | 26 +++++++++++++--------
mm/swapfile.c | 30 +++++++++++-------------
4 files changed, 66 insertions(+), 61 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index f4237a2e3b93..22af9f3e8c75 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3786,13 +3786,13 @@ static vm_fault_t handle_pte_marker(struct vm_fault *vmf)
vm_fault_t do_swap_page(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
- struct folio *swapcache, *folio = NULL;
+ struct folio *swapcache = NULL, *folio = NULL;
+ enum swap_cache_result cache_result;
struct page *page;
struct swap_info_struct *si = NULL;
rmap_t rmap_flags = RMAP_NONE;
bool exclusive = false;
swp_entry_t entry;
- bool swapcached;
pte_t pte;
vm_fault_t ret = 0;
@@ -3850,42 +3850,37 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
if (unlikely(!si))
goto out;
- folio = swap_cache_get_folio(entry, vma, vmf->address);
- if (folio)
- page = folio_file_page(folio, swp_offset(entry));
- swapcache = folio;
-
- if (!folio) {
- page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
- vmf, &swapcached);
- if (page) {
- folio = page_folio(page);
- if (swapcached)
- swapcache = folio;
- } else {
+ page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
+ vmf, &cache_result);
+ if (page) {
+ folio = page_folio(page);
+ if (cache_result != SWAP_CACHE_HIT) {
+ /* Had to read the page from swap area: Major fault */
+ ret = VM_FAULT_MAJOR;
+ count_vm_event(PGMAJFAULT);
+ count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
+ }
+ if (cache_result != SWAP_CACHE_BYPASS)
+ swapcache = folio;
+ if (PageHWPoison(page)) {
/*
- * Back out if somebody else faulted in this pte
- * while we released the pte lock.
+ * hwpoisoned dirty swapcache pages are kept for killing
+ * owner processes (which may be unknown at hwpoison time)
*/
- vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
- vmf->address, &vmf->ptl);
- if (likely(vmf->pte &&
- pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
- ret = VM_FAULT_OOM;
- goto unlock;
+ ret = VM_FAULT_HWPOISON;
+ goto out_release;
}
-
- /* Had to read the page from swap area: Major fault */
- ret = VM_FAULT_MAJOR;
- count_vm_event(PGMAJFAULT);
- count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
- } else if (PageHWPoison(page)) {
+ } else {
/*
- * hwpoisoned dirty swapcache pages are kept for killing
- * owner processes (which may be unknown at hwpoison time)
+ * Back out if somebody else faulted in this pte
+ * while we released the pte lock.
*/
- ret = VM_FAULT_HWPOISON;
- goto out_release;
+ vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
+ vmf->address, &vmf->ptl);
+ if (likely(vmf->pte &&
+ pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
+ ret = VM_FAULT_OOM;
+ goto unlock;
}
ret |= folio_lock_or_retry(folio, vmf);
diff --git a/mm/swap.h b/mm/swap.h
index a9a654af791e..ac9136eee690 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -30,6 +30,12 @@ extern struct address_space *swapper_spaces[];
(&swapper_spaces[swp_type(entry)][swp_offset(entry) \
>> SWAP_ADDRESS_SPACE_SHIFT])
+enum swap_cache_result {
+ SWAP_CACHE_HIT,
+ SWAP_CACHE_MISS,
+ SWAP_CACHE_BYPASS,
+};
+
void show_swap_cache_info(void);
bool add_to_swap(struct folio *folio);
void *get_shadow_from_swap_cache(swp_entry_t entry);
@@ -55,7 +61,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
struct mempolicy *mpol, pgoff_t ilx);
struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
- struct vm_fault *vmf, bool *swapcached);
+ struct vm_fault *vmf, enum swap_cache_result *result);
static inline unsigned int folio_swap_flags(struct folio *folio)
{
@@ -92,7 +98,7 @@ static inline struct page *swap_cluster_readahead(swp_entry_t entry,
}
static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
- struct vm_fault *vmf, bool *swapcached)
+ struct vm_fault *vmf, enum swap_cache_result *result)
{
return NULL;
}
diff --git a/mm/swap_state.c b/mm/swap_state.c
index d87c20f9f7ec..e96d63bf8a22 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -908,8 +908,7 @@ static struct page *swapin_no_readahead(swp_entry_t entry, gfp_t gfp_mask,
* @entry: swap entry of this memory
* @gfp_mask: memory allocation flags
* @vmf: fault information
- * @swapcached: pointer to a bool used as indicator if the
- * page is swapped in through swapcache.
+ * @result: a return value to indicate swap cache usage.
*
* Returns the struct page for entry and addr, after queueing swapin.
*
@@ -918,30 +917,39 @@ static struct page *swapin_no_readahead(swp_entry_t entry, gfp_t gfp_mask,
* or vma-based(ie, virtual address based on faulty address) readahead.
*/
struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
- struct vm_fault *vmf, bool *swapcached)
+ struct vm_fault *vmf, enum swap_cache_result *result)
{
+ enum swap_cache_result cache_result;
struct swap_info_struct *si;
struct mempolicy *mpol;
+ struct folio *folio;
struct page *page;
pgoff_t ilx;
- bool cached;
+
+ folio = swap_cache_get_folio(entry, vmf->vma, vmf->address);
+ if (folio) {
+ page = folio_file_page(folio, swp_offset(entry));
+ cache_result = SWAP_CACHE_HIT;
+ goto done;
+ }
si = swp_swap_info(entry);
mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx);
if (swap_use_no_readahead(si, swp_offset(entry))) {
page = swapin_no_readahead(entry, gfp_mask, mpol, ilx, vmf->vma->vm_mm);
- cached = false;
+ cache_result = SWAP_CACHE_BYPASS;
} else if (swap_use_vma_readahead(si)) {
page = swap_vma_readahead(entry, gfp_mask, mpol, ilx, vmf);
- cached = true;
+ cache_result = SWAP_CACHE_MISS;
} else {
page = swap_cluster_readahead(entry, gfp_mask, mpol, ilx);
- cached = true;
+ cache_result = SWAP_CACHE_MISS;
}
mpol_cond_put(mpol);
- if (swapcached)
- *swapcached = cached;
+done:
+ if (result)
+ *result = cache_result;
return page;
}
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 01c3f53b6521..b6d57fff5e21 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1822,13 +1822,21 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
si = swap_info[type];
do {
- struct folio *folio;
+ struct page *page;
unsigned long offset;
unsigned char swp_count;
+ struct folio *folio = NULL;
swp_entry_t entry;
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)
@@ -1847,22 +1855,10 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
offset = swp_offset(entry);
pte_unmap(pte);
pte = NULL;
-
- folio = swap_cache_get_folio(entry, vma, addr);
- if (!folio) {
- struct page *page;
- struct vm_fault vmf = {
- .vma = vma,
- .address = addr,
- .real_address = addr,
- .pmd = pmd,
- };
-
- page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
- &vmf, NULL);
- if (page)
- folio = page_folio(page);
- }
+ page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
+ &vmf, NULL);
+ if (page)
+ folio = page_folio(page);
if (!folio) {
/*
* The entry could have been freed, and will not
--
2.42.0
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