mm: swap: unify cluster-based and vma-based swap readahead

This patch makes do_swap_page() not need to be aware of two different
swap readahead algorithms.  Just unify cluster-based and vma-based
readahead function call.

Link: http://lkml.kernel.org/r/1509520520-32367-3-git-send-email-minchan@kernel.org
Link: http://lkml.kernel.org/r/20180220085249.151400-3-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index fa92177d863ecb471736d4085694ae18abeb435e..2417d288e016609a4e844ba6b7e3b4c3ed3526d2 100644 (file)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -400,7 +400,6 @@ int generic_swapfile_activate(struct swap_info_struct *, struct file *,
 #define SWAP_ADDRESS_SPACE_SHIFT       14
 #define SWAP_ADDRESS_SPACE_PAGES       (1 << SWAP_ADDRESS_SPACE_SHIFT)
 extern struct address_space *swapper_spaces[];
-extern bool swap_vma_readahead;
 #define swap_address_space(entry)                          \
        (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
                >> SWAP_ADDRESS_SPACE_SHIFT])
@@ -422,10 +421,10 @@ extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
                        struct vm_area_struct *vma, unsigned long addr,
                        bool *new_page_allocated);
-extern struct page *swapin_readahead(swp_entry_t, gfp_t,
-                       struct vm_area_struct *vma, unsigned long addr);
-extern struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
-                                          struct vm_fault *vmf);
+extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
+                               struct vm_fault *vmf);
+extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
+                               struct vm_fault *vmf);
 
 /* linux/mm/swapfile.c */
 extern atomic_long_t nr_swap_pages;
@@ -433,11 +432,6 @@ extern long total_swap_pages;
 extern atomic_t nr_rotate_swap;
 extern bool has_usable_swap(void);
 
-static inline bool swap_use_vma_readahead(void)
-{
-       return READ_ONCE(swap_vma_readahead) && !atomic_read(&nr_rotate_swap);
-}
-
 /* Swap 50% full? Release swapcache more aggressively.. */
 static inline bool vm_swap_full(void)
 {
@@ -533,19 +527,14 @@ static inline void put_swap_page(struct page *page, swp_entry_t swp)
 {
 }
 
-static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
-                       struct vm_area_struct *vma, unsigned long addr)
+static inline struct page *swap_cluster_readahead(swp_entry_t entry,
+                               gfp_t gfp_mask, struct vm_fault *vmf)
 {
        return NULL;
 }
 
-static inline bool swap_use_vma_readahead(void)
-{
-       return false;
-}
-
-static inline struct page *do_swap_page_readahead(swp_entry_t fentry,
-                               gfp_t gfp_mask, struct vm_fault *vmf)
+static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
+                       struct vm_fault *vmf)
 {
        return NULL;
 }

diff --git a/mm/memory.c b/mm/memory.c
index bc1ccff795386f9dafdf091f51778ca224800ee8..01f5464e0fd28802753c0085e1d30f98a4557d3e 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2927,7 +2927,8 @@ int do_swap_page(struct vm_fault *vmf)
                if (si->flags & SWP_SYNCHRONOUS_IO &&
                                __swap_count(si, entry) == 1) {
                        /* skip swapcache */
-                       page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+                       page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
+                                                       vmf->address);
                        if (page) {
                                __SetPageLocked(page);
                                __SetPageSwapBacked(page);
@@ -2936,12 +2937,8 @@ int do_swap_page(struct vm_fault *vmf)
                                swap_readpage(page, true);
                        }
                } else {
-                       if (swap_use_vma_readahead())
-                               page = do_swap_page_readahead(entry,
-                                       GFP_HIGHUSER_MOVABLE, vmf);
-                       else
-                               page = swapin_readahead(entry,
-                                      GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+                       page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
+                                               vmf);
                        swapcache = page;
                }
 

diff --git a/mm/shmem.c b/mm/shmem.c
index b859192433998a14096629b53ac5297a6a0dd2bb..4424fc0c33aaf30e208a57e12e74dcf5d99afbd9 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1422,9 +1422,12 @@ static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
 {
        struct vm_area_struct pvma;
        struct page *page;
+       struct vm_fault vmf;
 
        shmem_pseudo_vma_init(&pvma, info, index);
-       page = swapin_readahead(swap, gfp, &pvma, 0);
+       vmf.vma = &pvma;
+       vmf.address = 0;
+       page = swap_cluster_readahead(swap, gfp, &vmf);
        shmem_pseudo_vma_destroy(&pvma);
 
        return page;

diff --git a/mm/swap_state.c b/mm/swap_state.c
index db5da2baafb101c719d0a2de2af1d199013c5af6..b97da97b6846ee217ca05408aaa7e7b7a9c50ca2 100644 (file)
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -38,7 +38,7 @@ static const struct address_space_operations swap_aops = {
 
 struct address_space *swapper_spaces[MAX_SWAPFILES] __read_mostly;
 static unsigned int nr_swapper_spaces[MAX_SWAPFILES] __read_mostly;
-bool swap_vma_readahead __read_mostly = true;
+bool enable_vma_readahead __read_mostly = true;
 
 #define SWAP_RA_WIN_SHIFT      (PAGE_SHIFT / 2)
 #define SWAP_RA_HITS_MASK      ((1UL << SWAP_RA_WIN_SHIFT) - 1)
@@ -322,6 +322,11 @@ void free_pages_and_swap_cache(struct page **pages, int nr)
        release_pages(pagep, nr);
 }
 
+static inline bool swap_use_vma_readahead(void)
+{
+       return READ_ONCE(enable_vma_readahead) && !atomic_read(&nr_rotate_swap);
+}
+
 /*
  * Lookup a swap entry in the swap cache. A found page will be returned
  * unlocked and with its refcount incremented - we rely on the kernel
@@ -544,11 +549,10 @@ static unsigned long swapin_nr_pages(unsigned long offset)
 }
 
 /**
- * swapin_readahead - swap in pages in hope we need them soon
+ * swap_cluster_readahead - swap in pages in hope we need them soon
  * @entry: swap entry of this memory
  * @gfp_mask: memory allocation flags
- * @vma: user vma this address belongs to
- * @addr: target address for mempolicy
+ * @vmf: fault information
  *
  * Returns the struct page for entry and addr, after queueing swapin.
  *
@@ -560,10 +564,10 @@ static unsigned long swapin_nr_pages(unsigned long offset)
  * This has been extended to use the NUMA policies from the mm triggering
  * the readahead.
  *
- * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
+ * Caller must hold down_read on the vma->vm_mm if vmf->vma is not NULL.
  */
-struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
-                       struct vm_area_struct *vma, unsigned long addr)
+struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
+                               struct vm_fault *vmf)
 {
        struct page *page;
        unsigned long entry_offset = swp_offset(entry);
@@ -573,6 +577,8 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
        struct swap_info_struct *si = swp_swap_info(entry);
        struct blk_plug plug;
        bool do_poll = true, page_allocated;
+       struct vm_area_struct *vma = vmf->vma;
+       unsigned long addr = vmf->address;
 
        mask = swapin_nr_pages(offset) - 1;
        if (!mask)
@@ -727,7 +733,7 @@ static void swap_ra_info(struct vm_fault *vmf,
        pte_unmap(orig_pte);
 }
 
-struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
+struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
                                    struct vm_fault *vmf)
 {
        struct blk_plug plug;
@@ -774,20 +780,40 @@ skip:
                                     ra_info.win == 1);
 }
 
+/**
+ * swapin_readahead - swap in pages in hope we need them soon
+ * @entry: swap entry of this memory
+ * @gfp_mask: memory allocation flags
+ * @vmf: fault information
+ *
+ * Returns the struct page for entry and addr, after queueing swapin.
+ *
+ * It's a main entry function for swap readahead. By the configuration,
+ * it will read ahead blocks by cluster-based(ie, physical disk based)
+ * 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)
+{
+       return swap_use_vma_readahead() ?
+                       swap_vma_readahead(entry, gfp_mask, vmf) :
+                       swap_cluster_readahead(entry, gfp_mask, vmf);
+}
+
 #ifdef CONFIG_SYSFS
 static ssize_t vma_ra_enabled_show(struct kobject *kobj,
                                     struct kobj_attribute *attr, char *buf)
 {
-       return sprintf(buf, "%s\n", swap_vma_readahead ? "true" : "false");
+       return sprintf(buf, "%s\n", enable_vma_readahead ? "true" : "false");
 }
 static ssize_t vma_ra_enabled_store(struct kobject *kobj,
                                      struct kobj_attribute *attr,
                                      const char *buf, size_t count)
 {
        if (!strncmp(buf, "true", 4) || !strncmp(buf, "1", 1))
-               swap_vma_readahead = true;
+               enable_vma_readahead = true;
        else if (!strncmp(buf, "false", 5) || !strncmp(buf, "0", 1))
-               swap_vma_readahead = false;
+               enable_vma_readahead = false;
        else
                return -EINVAL;