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linux/drivers/staging/lustre
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Michal Hocko 063d99b4fa mm, fs: obey gfp_mapping for add_to_page_cache() 
Commit 6afdb859b7 ("mm: do not ignore mapping_gfp_mask in page cache
allocation paths") has caught some users of hardcoded GFP_KERNEL used in
the page cache allocation paths.  This, however, wasn't complete and
there were others which went unnoticed.

Dave Chinner has reported the following deadlock for xfs on loop device:
: With the recent merge of the loop device changes, I'm now seeing
: XFS deadlock on my single CPU, 1GB RAM VM running xfs/073.
:
: The deadlocked is as follows:
:
: kloopd1: loop_queue_read_work
:       xfs_file_iter_read
:       lock XFS inode XFS_IOLOCK_SHARED (on image file)
:       page cache read (GFP_KERNEL)
:       radix tree alloc
:       memory reclaim
:       reclaim XFS inodes
:       log force to unpin inodes
:       <wait for log IO completion>
:
: xfs-cil/loop1: <does log force IO work>
:       xlog_cil_push
:       xlog_write
:       <loop issuing log writes>
:               xlog_state_get_iclog_space()
:               <blocks due to all log buffers under write io>
:               <waits for IO completion>
:
: kloopd1: loop_queue_write_work
:       xfs_file_write_iter
:       lock XFS inode XFS_IOLOCK_EXCL (on image file)
:       <wait for inode to be unlocked>
:
: i.e. the kloopd, with it's split read and write work queues, has
: introduced a dependency through memory reclaim. i.e. that writes
: need to be able to progress for reads make progress.
:
: The problem, fundamentally, is that mpage_readpages() does a
: GFP_KERNEL allocation, rather than paying attention to the inode's
: mapping gfp mask, which is set to GFP_NOFS.
:
: The didn't used to happen, because the loop device used to issue
: reads through the splice path and that does:
:
:       error = add_to_page_cache_lru(page, mapping, index,
:                       GFP_KERNEL & mapping_gfp_mask(mapping));

This has changed by commit aa4d86163e ("block: loop: switch to VFS
ITER_BVEC").

This patch changes mpage_readpage{s} to follow gfp mask set for the
mapping.  There are, however, other places which are doing basically the
same.

lustre:ll_dir_filler is doing GFP_KERNEL from the function which
apparently uses GFP_NOFS for other allocations so let's make this
consistent.

cifs:readpages_get_pages is called from cifs_readpages and
__cifs_readpages_from_fscache called from the same path obeys mapping
gfp.

ramfs_nommu_expand_for_mapping is hardcoding GFP_KERNEL as well
regardless it uses mapping_gfp_mask for the page allocation.

ext4_mpage_readpages is the called from the page cache allocation path
same as read_pages and read_cache_pages

As I've noticed in my previous post I cannot say I would be happy about
sprinkling mapping_gfp_mask all over the place and it sounds like we
should drop gfp_mask argument altogether and use it internally in
__add_to_page_cache_locked that would require all the filesystems to use
mapping gfp consistently which I am not sure is the case here.  From a
quick glance it seems that some file system use it all the time while
others are selective.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Dave Chinner <david@fromorbit.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-16 11:42:28 -07:00
..
include/linux staging: lustre-libcfs: fix sparse warning 2015-08-14 18:46:02 -07:00
lnet staging/lustre/o2iblnd: remove references to ib_reg_phsy_mr() 2015-08-18 19:53:41 -07:00
lustre mm, fs: obey gfp_mapping for add_to_page_cache() 2015-10-16 11:42:28 -07:00
Kconfig
Makefile staging: lustre: remove top level ccflags variable 2014-07-11 20:51:16 -07:00
README.txt staging/lustre: change Lustre URLs and mailing list 2015-09-13 09:28:27 -07:00
sysfs-fs-lustre staging/lustre/obdclass: Move AT controls from sysctl to sysfs 2015-07-13 19:47:20 -07:00
TODO Staging: fixed multiple spelling errors. 2015-05-08 09:23:58 +02:00

README.txt 

Lustre Parallel Filesystem Client
=================================

The Lustre file system is an open-source, parallel file system
that supports many requirements of leadership class HPC simulation
environments.
Born from from a research project at Carnegie Mellon University,
the Lustre file system is a widely-used option in HPC.
The Lustre file system provides a POSIX compliant file system interface,
can scale to thousands of clients, petabytes of storage and
hundreds of gigabytes per second of I/O bandwidth.

Unlike shared disk storage cluster filesystems (e.g. OCFS2, GFS, GPFS),
Lustre has independent Metadata and Data servers that clients can access
in parallel to maximize performance.

In order to use Lustre client you will need to download the "lustre-client"
package that contains the userspace tools from http://lustre.org/download/

You will need to install and configure your Lustre servers separately.

Mount Syntax
============
After you installed the lustre-client tools including mount.lustre binary
you can mount your Lustre filesystem with:

mount -t lustre mgs:/fsname mnt

where mgs is the host name or ip address of your Lustre MGS(management service)
fsname is the name of the filesystem you would like to mount.


Mount Options
=============

  noflock
	Disable posix file locking (Applications trying to use
	the functionality will get ENOSYS)

  localflock
	Enable local flock support, using only client-local flock
	(faster, for applications that require flock but do not run
	 on multiple nodes).

  flock
	Enable cluster-global posix file locking coherent across all
	client nodes.

  user_xattr, nouser_xattr
	Support "user." extended attributes (or not)

  user_fid2path, nouser_fid2path
	Enable FID to path translation by regular users (or not)

  checksum, nochecksum
	Verify data consistency on the wire and in memory as it passes
	between the layers (or not).

  lruresize, nolruresize
	Allow lock LRU to be controlled by memory pressure on the server
	(or only 100 (default, controlled by lru_size proc parameter) locks
	 per CPU per server on this client).

  lazystatfs, nolazystatfs
	Do not block in statfs() if some of the servers are down.

  32bitapi
	Shrink inode numbers to fit into 32 bits. This is necessary
	if you plan to reexport Lustre filesystem from this client via
	NFSv4.

  verbose, noverbose
	Enable mount/umount console messages (or not)

More Information
================
You can get more information at the Lustre website: http://wiki.lustre.org/

Source for the userspace tools and out-of-tree client and server code
is available at: http://git.hpdd.intel.com/fs/lustre-release.git

Latest binary packages:
http://lustre.org/download/