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Message-ID: <20130716133450.GD5403@kvack.org>
Date: Tue, 16 Jul 2013 09:34:50 -0400
From: Benjamin LaHaise <bcrl@...ck.org>
To: Gu Zheng <guz.fnst@...fujitsu.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...e.de>,
Al Viro <viro@...iv.linux.org.uk>,
tangchen <tangchen@...fujitsu.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Subject: Re: [PATCH RESEND 2/2] fs/aio: Add support to aio ring pages migration
On Tue, Jul 16, 2013 at 05:56:16PM +0800, Gu Zheng wrote:
> As the aio job will pin the ring pages, that will lead to mem migrated
> failed. In order to fix this problem we use an anon inode to manage the aio ring
> pages, and setup the migratepage callback in the anon inode's address space, so
> that when mem migrating the aio ring pages will be moved to other mem node safely.
There are a few minor issues that needed to be fixed -- see below. I've
made these changes and added them to git://git.kvack.org/~bcrl/aio-next.git ,
and will ask for that tree to be included in linux-next.
mm folks: can someone familiar with page migration / hot plug memory please
review the migration changes?
>
> Signed-off-by: Gu Zheng <guz.fnst@...fujitsu.com>
> Signed-off-by: Benjamin LaHaise <bcrl@...ck.org>
Again, I had not provided my Signed-off-by on this patch previously, so
don't add it for me.
> ---
> fs/aio.c | 120 ++++++++++++++++++++++++++++++++++++++++++----
> include/linux/migrate.h | 3 +
> mm/migrate.c | 2 +-
> 3 files changed, 113 insertions(+), 12 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index 9b5ca11..d10f956 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -35,6 +35,9 @@
> #include <linux/eventfd.h>
> #include <linux/blkdev.h>
> #include <linux/compat.h>
> +#include <linux/anon_inodes.h>
> +#include <linux/migrate.h>
> +#include <linux/ramfs.h>
>
> #include <asm/kmap_types.h>
> #include <asm/uaccess.h>
> @@ -110,6 +113,7 @@ struct kioctx {
> } ____cacheline_aligned_in_smp;
>
> struct page *internal_pages[AIO_RING_PAGES];
> + struct file *aio_ring_file;
> };
>
> /*------ sysctl variables----*/
> @@ -138,15 +142,78 @@ __initcall(aio_setup);
>
> static void aio_free_ring(struct kioctx *ctx)
> {
> - long i;
> + int i;
> + struct file *aio_ring_file = ctx->aio_ring_file;
>
> - for (i = 0; i < ctx->nr_pages; i++)
> + for (i = 0; i < ctx->nr_pages; i++) {
> + pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
> + page_count(ctx->ring_pages[i]));
> put_page(ctx->ring_pages[i]);
> + }
>
> if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
> kfree(ctx->ring_pages);
> +
> + if (aio_ring_file) {
> + truncate_setsize(aio_ring_file->f_inode, 0);
> + pr_debug("pid(%d) i_nlink=%u d_count=%d d_unhashed=%d i_count=%d\n",
> + current->pid, aio_ring_file->f_inode->i_nlink,
> + aio_ring_file->f_path.dentry->d_count,
> + d_unhashed(aio_ring_file->f_path.dentry),
> + atomic_read(&aio_ring_file->f_inode->i_count));
> + fput(aio_ring_file);
> + ctx->aio_ring_file = NULL;
> + }
> +}
> +
> +static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> + vma->vm_ops = &generic_file_vm_ops;
> + return 0;
> +}
> +
> +static const struct file_operations aio_ring_fops = {
> + .mmap = aio_ring_mmap,
> +};
> +
> +static int aio_set_page_dirty(struct page *page)
> +{
> + return 0;
> }
>
> +static int aio_migratepage(struct address_space *mapping, struct page *new,
> + struct page *old, enum migrate_mode mode)
> +{
> + struct kioctx *ctx = mapping->private_data;
> + unsigned long flags;
> + unsigned idx = old->index;
> + int rc;
> +
> + /*Writeback must be complete*/
Missing spaces before/after beginning and end of comment.
> + BUG_ON(PageWriteback(old));
> + put_page(old);
> +
> + rc = migrate_page_move_mapping(mapping, new, old, NULL, mode);
> + if (rc != MIGRATEPAGE_SUCCESS) {
> + get_page(old);
> + return rc;
> + }
> +
> + get_page(new);
> +
> + spin_lock_irqsave(&ctx->completion_lock, flags);
> + migrate_page_copy(new, old);
> + ctx->ring_pages[idx] = new;
> + spin_unlock_irqrestore(&ctx->completion_lock, flags);
> +
> + return rc;
> +}
> +
> +static const struct address_space_operations aio_ctx_aops = {
> + .set_page_dirty = aio_set_page_dirty,
> + .migratepage = aio_migratepage,
> +};
> +
> static int aio_setup_ring(struct kioctx *ctx)
> {
> struct aio_ring *ring;
> @@ -154,20 +221,45 @@ static int aio_setup_ring(struct kioctx *ctx)
> struct mm_struct *mm = current->mm;
> unsigned long size, populate;
> int nr_pages;
> + int i;
> + struct file *file;
>
> /* Compensate for the ring buffer's head/tail overlap entry */
> nr_events += 2; /* 1 is required, 2 for good luck */
>
> size = sizeof(struct aio_ring);
> size += sizeof(struct io_event) * nr_events;
> - nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
>
> + nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
Hrm, this should probably be replaced by PFN_UP(size) rather than the old
open coding of same.
> if (nr_pages < 0)
> return -EINVAL;
>
> - nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
> + file = anon_inode_getfile_private("[aio]", &aio_ring_fops, ctx, O_RDWR);
> + if (IS_ERR(file)) {
> + ctx->aio_ring_file = NULL;
> + return -EAGAIN;
> + }
> +
> + file->f_inode->i_mapping->a_ops = &aio_ctx_aops;
> + file->f_inode->i_mapping->private_data = ctx;
> + file->f_inode->i_size = PAGE_SIZE * (loff_t)nr_pages;
> +
> + for (i = 0; i < nr_pages; i++) {
> + struct page *page;
> + page = find_or_create_page(file->f_inode->i_mapping,
> + i, GFP_HIGHUSER | __GFP_ZERO);
> + if (!page)
> + break;
> + pr_debug("pid(%d) page[%d]->count=%d\n",
> + current->pid, i, page_count(page));
> + SetPageUptodate(page);
> + SetPageDirty(page);
> + unlock_page(page);
> + }
> + ctx->aio_ring_file = file;
> + nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
> + / sizeof(struct io_event);
>
> - ctx->nr_events = 0;
> ctx->ring_pages = ctx->internal_pages;
> if (nr_pages > AIO_RING_PAGES) {
> ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
> @@ -178,28 +270,31 @@ static int aio_setup_ring(struct kioctx *ctx)
>
> ctx->mmap_size = nr_pages * PAGE_SIZE;
> pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
> +
> down_write(&mm->mmap_sem);
> - ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size,
> - PROT_READ|PROT_WRITE,
> - MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate);
> + ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
> + PROT_READ | PROT_WRITE,
> + MAP_SHARED | MAP_POPULATE, 0, &populate);
> if (IS_ERR((void *)ctx->mmap_base)) {
> up_write(&mm->mmap_sem);
> ctx->mmap_size = 0;
> aio_free_ring(ctx);
> return -EAGAIN;
> }
> + up_write(&mm->mmap_sem);
> +
> + mm_populate(ctx->mmap_base, populate);
>
> pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
> ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
> 1, 0, ctx->ring_pages, NULL);
> - up_write(&mm->mmap_sem);
> + for (i = 0; i < ctx->nr_pages; i++)
> + put_page(ctx->ring_pages[i]);
>
> if (unlikely(ctx->nr_pages != nr_pages)) {
> aio_free_ring(ctx);
> return -EAGAIN;
> }
> - if (populate)
> - mm_populate(ctx->mmap_base, populate);
>
> ctx->user_id = ctx->mmap_base;
> ctx->nr_events = nr_events; /* trusted copy */
> @@ -399,6 +494,8 @@ out_cleanup:
> err = -EAGAIN;
> aio_free_ring(ctx);
> out_freectx:
> + if (ctx->aio_ring_file)
> + fput(ctx->aio_ring_file);
> kmem_cache_free(kioctx_cachep, ctx);
> pr_debug("error allocating ioctx %d\n", err);
> return ERR_PTR(err);
> @@ -852,6 +949,7 @@ SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
> ioctx = ioctx_alloc(nr_events);
> ret = PTR_ERR(ioctx);
> if (!IS_ERR(ioctx)) {
> + ctx = ioctx->user_id;
> ret = put_user(ioctx->user_id, ctxp);
> if (ret)
> kill_ioctx(ioctx);
This hunk doesn't do anything and needs to be removed. That should cover
things.
-ben
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index a405d3dc..c407d88 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -55,6 +55,9 @@ extern int migrate_vmas(struct mm_struct *mm,
> extern void migrate_page_copy(struct page *newpage, struct page *page);
> extern int migrate_huge_page_move_mapping(struct address_space *mapping,
> struct page *newpage, struct page *page);
> +extern int migrate_page_move_mapping(struct address_space *mapping,
> + struct page *newpage, struct page *page,
> + struct buffer_head *head, enum migrate_mode mode);
> #else
>
> static inline void putback_lru_pages(struct list_head *l) {}
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 6f0c244..1da0092 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -307,7 +307,7 @@ static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
> * 2 for pages with a mapping
> * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
> */
> -static int migrate_page_move_mapping(struct address_space *mapping,
> +int migrate_page_move_mapping(struct address_space *mapping,
> struct page *newpage, struct page *page,
> struct buffer_head *head, enum migrate_mode mode)
> {
> --
> 1.7.7
>
--
"Thought is the essence of where you are now."
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