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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html