The patch titled
Subject: mm: make madvise(MADV_WILLNEED) support swap file prefetch
has been added to the -mm tree. Its filename is
mm-make-madvisemadv_willneed-support-swap-file-prefetch.patch
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------------------------------------------------------
From: Shaohua Li <shli@xxxxxxxxxx>
Subject: mm: make madvise(MADV_WILLNEED) support swap file prefetch
Make madvise(MADV_WILLNEED) support swap file prefetch. If memory is
swapout, this syscall can do swapin prefetch. It has no impact if the
memory isn't swapout.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/madvise.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 94 insertions(+)
diff -puN mm/madvise.c~mm-make-madvisemadv_willneed-support-swap-file-prefetch mm/madvise.c
--- a/mm/madvise.c~mm-make-madvisemadv_willneed-support-swap-file-prefetch
+++ a/mm/madvise.c
@@ -16,6 +16,9 @@
#include <linux/ksm.h>
#include <linux/fs.h>
#include <linux/file.h>
+#include <linux/blkdev.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
/*
* Any behaviour which results in changes to the vma->vm_flags needs to
@@ -131,6 +134,82 @@ out:
return error;
}
+static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
+ unsigned long end, struct mm_walk *walk)
+{
+ pte_t *orig_pte;
+ struct vm_area_struct *vma = walk->private;
+ unsigned long index;
+
+ if (pmd_none_or_trans_huge_or_clear_bad(pmd))
+ return 0;
+
+ for (index = start; index != end; index += PAGE_SIZE) {
+ pte_t pte;
+ swp_entry_t entry;
+ struct page *page;
+ spinlock_t *ptl;
+
+ orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
+ pte = *(orig_pte + ((index - start) / PAGE_SIZE));
+ pte_unmap_unlock(orig_pte, ptl);
+
+ if (pte_present(pte) || pte_none(pte) || pte_file(pte))
+ continue;
+ entry = pte_to_swp_entry(pte);
+ if (unlikely(non_swap_entry(entry)))
+ continue;
+
+ page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
+ vma, index);
+ if (page)
+ page_cache_release(page);
+ }
+
+ return 0;
+}
+
+static void force_swapin_readahead(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end)
+{
+ struct mm_walk walk = {
+ .mm = vma->vm_mm,
+ .pmd_entry = swapin_walk_pmd_entry,
+ .private = vma,
+ };
+
+ walk_page_range(start, end, &walk);
+
+ lru_add_drain(); /* Push any new pages onto the LRU now */
+}
+
+static void force_shm_swapin_readahead(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end,
+ struct address_space *mapping)
+{
+ pgoff_t index;
+ struct page *page;
+ swp_entry_t swap;
+
+ for (; start < end; start += PAGE_SIZE) {
+ index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+
+ page = find_get_page(mapping, index);
+ if (!radix_tree_exceptional_entry(page)) {
+ if (page)
+ page_cache_release(page);
+ continue;
+ }
+ swap = radix_to_swp_entry(page);
+ page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
+ NULL, 0);
+ if (page)
+ page_cache_release(page);
+ }
+
+ lru_add_drain(); /* Push any new pages onto the LRU now */
+}
+
/*
* Schedule all required I/O operations. Do not wait for completion.
*/
@@ -140,6 +219,18 @@ static long madvise_willneed(struct vm_a
{
struct file *file = vma->vm_file;
+#ifdef CONFIG_SWAP
+ if (!file || mapping_cap_swap_backed(file->f_mapping)) {
+ *prev = vma;
+ if (!file)
+ force_swapin_readahead(vma, start, end);
+ else
+ force_shm_swapin_readahead(vma, start, end,
+ file->f_mapping);
+ return 0;
+ }
+#endif
+
if (!file)
return -EBADF;
@@ -371,6 +462,7 @@ SYSCALL_DEFINE3(madvise, unsigned long,
int error = -EINVAL;
int write;
size_t len;
+ struct blk_plug plug;
#ifdef CONFIG_MEMORY_FAILURE
if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
@@ -410,6 +502,7 @@ SYSCALL_DEFINE3(madvise, unsigned long,
if (vma && start > vma->vm_start)
prev = vma;
+ blk_start_plug(&plug);
for (;;) {
/* Still start < end. */
error = -ENOMEM;
@@ -445,6 +538,7 @@ SYSCALL_DEFINE3(madvise, unsigned long,
vma = find_vma(current->mm, start);
}
out:
+ blk_finish_plug(&plug);
if (write)
up_write(¤t->mm->mmap_sem);
else
_
Patches currently in -mm which might be from shli@xxxxxxxxxx are
linux-next.patch
mm-make-madvisemadv_willneed-support-swap-file-prefetch.patch
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