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SubjectRe: [PATCH RESEND 2/2] fs/aio: Add support to aio ring pages migration
Hi Ben,

On 07/16/2013 09:34 PM, Benjamin LaHaise wrote:

> 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.

Thanks very much, and your review.
Stephen sent out a build failed msg when merger this patch into next-tree from your aio_next.
This is because we use migrate_page_move_mapping() which is protected by CONFIG_MIGRATION, I'll
fix this issue in the next version.

Best regards,
Gu


>
> mm folks: can someone familiar with page migration / hot plug memory please
> review the migration changes?
>
>>
>> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
>> Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
>
> Again, I had not provided my Signed-off-by on this patch previously, so
> don't add it for me.

Sorry again.:)

>
>> ---
>> 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
>>
>




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