kernel.git/mm/page_io.c, branch linux-3.11.y

mm: remove compressed copy from zram in-memory

2013-07-03T23:07:26Z

Swap subsystem does lazy swap slot free with expecting the page would be swapped out again so we can avoid unnecessary write. But the problem in in-memory swap(ex, zram) is that it consumes memory space until vm_swap_full(ie, used half of all of swap device) condition meet. It could be bad if we use multiple swap device, small in-memory swap and big storage swap or in-memory swap alone. This patch makes swap subsystem free swap slot as soon as swap-read is completed and make the swapcache page dirty so the page should be written out the swap device to reclaim it. It means we never lose it. I tested this patch with kernel compile workload. 1. before compile time : 9882.42 zram max wasted space by fragmentation: 13471881 byte memory space consumed by zram: 174227456 byte the number of slot free notify: 206684 2. after compile time : 9653.90 zram max wasted space by fragmentation: 11805932 byte memory space consumed by zram: 154001408 byte the number of slot free notify: 426972 [akpm@linux-foundation.org: tweak comment text] [artem.savkov@gmail.com: fix BUG due to non-swapcache pages in end_swap_bio_read()] [akpm@linux-foundation.org: invert unlikely() test, augment comment, 80-col cleanup] Signed-off-by: Dan Magenheimer Signed-off-by: Minchan Kim Signed-off-by: Artem Savkov Cc: Hugh Dickins Cc: Seth Jennings Cc: Nitin Gupta Cc: Konrad Rzeszutek Wilk Cc: Shaohua Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-3.10/core' of git://git.kernel.dk/linux-block

2013-05-08T17:13:35Z

Pull block core updates from Jens Axboe: - Major bit is Kents prep work for immutable bio vecs. - Stable candidate fix for a scheduling-while-atomic in the queue bypass operation. - Fix for the hang on exceeded rq->datalen 32-bit unsigned when merging discard bios. - Tejuns changes to convert the writeback thread pool to the generic workqueue mechanism. - Runtime PM framework, SCSI patches exists on top of these in James' tree. - A few random fixes. * 'for-3.10/core' of git://git.kernel.dk/linux-block: (40 commits) relay: move remove_buf_file inside relay_close_buf partitions/efi.c: replace useless kzalloc's by kmalloc's fs/block_dev.c: fix iov_shorten() criteria in blkdev_aio_read() block: fix max discard sectors limit blkcg: fix "scheduling while atomic" in blk_queue_bypass_start Documentation: cfq-iosched: update documentation help for cfq tunables writeback: expose the bdi_wq workqueue writeback: replace custom worker pool implementation with unbound workqueue writeback: remove unused bdi_pending_list aoe: Fix unitialized var usage bio-integrity: Add explicit field for owner of bip_buf block: Add an explicit bio flag for bios that own their bvec block: Add bio_alloc_pages() block: Convert some code to bio_for_each_segment_all() block: Add bio_for_each_segment_all() bounce: Refactor __blk_queue_bounce to not use bi_io_vec raid1: use bio_copy_data() pktcdvd: Use bio_reset() in disabled code to kill bi_idx usage pktcdvd: use bio_copy_data() block: Add bio_copy_data() ...

aio: don't include aio.h in sched.h

2013-05-08T03:16:25Z

Faster kernel compiles by way of fewer unnecessary includes. [akpm@linux-foundation.org: fix fallout] [akpm@linux-foundation.org: fix build] Signed-off-by: Kent Overstreet Cc: Zach Brown Cc: Felipe Balbi Cc: Greg Kroah-Hartman Cc: Mark Fasheh Cc: Joel Becker Cc: Rusty Russell Cc: Jens Axboe Cc: Asai Thambi S P Cc: Selvan Mani Cc: Sam Bradshaw Cc: Jeff Moyer Cc: Al Viro Cc: Benjamin LaHaise Reviewed-by: "Theodore Ts'o" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: swap: mark swap pages writeback before queueing for direct IO

2013-04-29T22:54:39Z

As pointed out by Andrew Morton, the swap-over-NFS writeback is not setting PageWriteback before it is queued for direct IO. While swap pages do not participate in BDI or process dirty accounting and the IO is synchronous, the writeback bit is still required and not setting it in this case was an oversight. swapoff depends on the page writeback to synchronoise all pending writes on a swap page before it is reused. Swapcache freeing and reuse depend on checking the PageWriteback under lock to ensure the page is safe to reuse. Direct IO handlers and the direct IO handler for NFS do not deal with PageWriteback as they are synchronous writes. In the case of NFS, it schedules pages (or a page in the case of swap) for IO and then waits synchronously for IO to complete in nfs_direct_write(). It is recognised that this is a slowdown from normal swap handling which is asynchronous and uses a completion handler. Shoving PageWriteback handling down into direct IO handlers looks like a bad fit to handle the swap case although it may have to be dealt with some day if swap is converted to use direct IO in general and bmap is finally done away with. At that point it will be necessary to refit asynchronous direct IO with completion handlers onto the swap subsystem. As swapcache currently depends on PageWriteback to protect against races, this patch sets PageWriteback under the page lock before queueing it for direct IO. It is cleared when the direct IO handler returns. IO errors are treated similarly to the direct-to-bio case except PageError is not set as in the case of swap-over-NFS, it is likely to be a transient error. It was asked what prevents such a page being reclaimed in parallel. With this patch applied, such a page will now be skipped (most of the time) or blocked until the writeback completes. Reclaim checks PageWriteback under the page lock before calling try_to_free_swap and the page lock should prevent the page being requeued for IO before it is freed. This and Jerome's related patch should considered for -stable as far back as 3.6 when swap-over-NFS was introduced. [akpm@linux-foundation.org: use pr_err_ratelimited()] [akpm@linux-foundation.org: remove hopefully-unneeded cast in printk] Signed-off-by: Mel Gorman Cc: Jerome Marchand Cc: Hugh Dickins Cc: [3.6+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

swap: redirty page if page write fails on swap file

2013-04-29T22:54:39Z

Since commit 62c230bc1790 ("mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages"), swap_writepage() calls direct_IO on swap files. However, in that case the page isn't redirtied if I/O fails, and is therefore handled afterwards as if it has been successfully written to the swap file, leading to memory corruption when the page is eventually swapped back in. This patch sets the page dirty when direct_IO() fails. It fixes a memory corruption that happened while using swap-over-NFS. Signed-off-by: Jerome Marchand Acked-by: Johannes Weiner Acked-by: Mel Gorman Cc: Hugh Dickins Cc: [3.6+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: allow for outstanding swap writeback accounting

2013-04-29T22:54:38Z

To prevent flooding the swap device with writebacks, frontswap backends need to count and limit the number of outstanding writebacks. The incrementing of the counter can be done before the call to __swap_writepage(). However, the caller must receive a notification when the writeback completes in order to decrement the counter. To achieve this functionality, this patch modifies __swap_writepage() to take the bio completion callback function as an argument. end_swap_bio_write(), the normal bio completion function, is also made non-static so that code doing the accounting can call it after the accounting is done. There should be no behavioural change to existing code. Signed-off-by: Seth Jennings Signed-off-by: Bob Liu Acked-by: Minchan Kim Reviewed-by: Dan Magenheimer Cc: Konrad Rzeszutek Wilk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: break up swap_writepage() for frontswap backends

2013-04-29T22:54:38Z

swap_writepage() is currently where frontswap hooks into the swap write path to capture pages with the frontswap_store() function. However, if a frontswap backend wants to "resume" the writeback of a page to the swap device, it can't call swap_writepage() as the page will simply reenter the backend. This patch separates swap_writepage() into a top and bottom half, the bottom half named __swap_writepage() to allow a frontswap backend, like zswap, to resume writeback beyond the frontswap_store() hook. __add_to_swap_cache() is also made non-static so that the page for which writeback is to be resumed can be added to the swap cache. Signed-off-by: Seth Jennings Signed-off-by: Bob Liu Acked-by: Minchan Kim Reviewed-by: Dan Magenheimer Cc: Konrad Rzeszutek Wilk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

block: Remove bi_idx references

2013-03-23T21:15:31Z

For immutable bvecs, all bi_idx usage needs to be audited - so here we're removing all the unnecessary uses. Most of these are places where it was being initialized on a bio that was just allocated, a few others are conversions to standard macros. Signed-off-by: Kent Overstreet CC: Jens Axboe

mm: add support for direct_IO to highmem pages

2012-08-01T01:42:47Z

The patch "mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages" added support for using direct_IO to write swap pages but it is insufficient for highmem pages. To support highmem pages, this patch kmaps() the page before calling the direct_IO() handler. As direct_IO deals with virtual addresses an additional helper is necessary for get_kernel_pages() to lookup the struct page for a kmap virtual address. Signed-off-by: Mel Gorman Acked-by: Rik van Riel Cc: Christoph Hellwig Cc: David S. Miller Cc: Eric B Munson Cc: Eric Paris Cc: James Morris Cc: Mel Gorman Cc: Mike Christie Cc: Neil Brown Cc: Peter Zijlstra Cc: Sebastian Andrzej Siewior Cc: Trond Myklebust Cc: Xiaotian Feng Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: swap: implement generic handler for swap_activate

2012-08-01T01:42:47Z

The version of swap_activate introduced is sufficient for swap-over-NFS but would not provide enough information to implement a generic handler. This patch shuffles things slightly to ensure the same information is available for aops->swap_activate() as is available to the core. No functionality change. Signed-off-by: Mel Gorman Acked-by: Rik van Riel Cc: Christoph Hellwig Cc: David S. Miller Cc: Eric B Munson Cc: Eric Paris Cc: James Morris Cc: Mel Gorman Cc: Mike Christie Cc: Neil Brown Cc: Peter Zijlstra Cc: Sebastian Andrzej Siewior Cc: Trond Myklebust Cc: Xiaotian Feng Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds