linux-stable.git/drivers/block/zram, branch linux-4.8.y

zram: restrict add/remove attributes to root only

2016-12-15T16:50:34+00:00

commit 5c7e9ccd91b90d87029261f8856294ee51934cab upstream.

zram hot_add sysfs attribute is a very 'special' attribute - reading
from it creates a new uninitialized zram device.  This file, by a
mistake, can be read by a 'normal' user at the moment, while only root
must be able to create a new zram device, therefore hot_add attribute
must have S_IRUSR mode, not S_IRUGO.

[akpm@linux-foundation.org: s/sence/sense/, reflow comment to use 80 cols]
Fixes: 6566d1a32bf72 ("zram: add dynamic device add/remove functionality")
Link: http://lkml.kernel.org/r/20161205155845.20129-1-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky 
Reported-by: Steven Allen 
Acked-by: Greg Kroah-Hartman 
Cc: Minchan Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

zram: fix unbalanced idr management at hot removal

2016-12-08T06:16:18+00:00

commit 529e71e16403830ae0d737a66c55c5f360f3576b upstream.

The zram hot removal code calls idr_remove() even when zram_remove()
returns an error (typically -EBUSY).  This results in a leftover at the
device release, eventually leading to a crash when the module is
reloaded.

As described in the bug report below, the following procedure would
cause an Oops with zram:

 - provision three zram devices via modprobe zram num_devices=3
 - configure a size for each device
   + echo "1G" > /sys/block/$zram_name/disksize
 - mkfs and mount zram0 only
 - attempt to hot remove all three devices
   + echo 2 > /sys/class/zram-control/hot_remove
   + echo 1 > /sys/class/zram-control/hot_remove
   + echo 0 > /sys/class/zram-control/hot_remove
     - zram0 removal fails with EBUSY, as expected
 - unmount zram0
 - try zram0 hot remove again
   + echo 0 > /sys/class/zram-control/hot_remove
     - fails with ENODEV (unexpected)
 - unload zram kernel module
   + completes successfully
 - zram0 device node still exists
 - attempt to mount /dev/zram0
   + mount command is killed
   + following BUG is encountered

 BUG: unable to handle kernel paging request at ffffffffa0002ba0
 IP: get_disk+0x16/0x50
 Oops: 0000 [#1] SMP
 CPU: 0 PID: 252 Comm: mount Not tainted 4.9.0-rc6 #176
 Call Trace:
   exact_lock+0xc/0x20
   kobj_lookup+0xdc/0x160
   get_gendisk+0x2f/0x110
   __blkdev_get+0x10c/0x3c0
   blkdev_get+0x19d/0x2e0
   blkdev_open+0x56/0x70
   do_dentry_open.isra.19+0x1ff/0x310
   vfs_open+0x43/0x60
   path_openat+0x2c9/0xf30
   do_filp_open+0x79/0xd0
   do_sys_open+0x114/0x1e0
   SyS_open+0x19/0x20
   entry_SYSCALL_64_fastpath+0x13/0x94

This patch adds the proper error check in hot_remove_store() not to call
idr_remove() unconditionally.

Fixes: 17ec4cd98578 ("zram: don't call idr_remove() from zram_remove()")
Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1010970
Link: http://lkml.kernel.org/r/20161121132140.12683-1-tiwai@suse.de
Signed-off-by: Takashi Iwai 
Reviewed-by: David Disseldorp 
Reported-by: David Disseldorp 
Tested-by: David Disseldorp 
Acked-by: Minchan Kim 
Acked-by: Sergey Senozhatsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

block/mm: make bdev_ops->rw_page() take a bool for read/write

2016-08-07T20:41:02+00:00

Commit abf545484d31 changed it from an 'rw' flags type to the
newer ops based interface, but now we're effectively leaking
some bdev internals to the rest of the kernel. Since we only
care about whether it's a read or a write at that level, just
pass in a bool 'is_write' parameter instead.

Then we can also move op_is_write() and friends back under
CONFIG_BLOCK protection.

Reviewed-by: Mike Christie 
Signed-off-by: Jens Axboe

mm/block: convert rw_page users to bio op use

2016-08-04T20:25:33+00:00

The rw_page users were not converted to use bio/req ops. As a result
bdev_write_page is not passing down REQ_OP_WRITE and the IOs will
be sent down as reads.

Signed-off-by: Mike Christie 
Fixes: 4e1b2d52a80d ("block, fs, drivers: remove REQ_OP compat defs and related code")

Modified by me to:

1) Drop op_flags passing into ->rw_page(), as we don't use it.
2) Make op_is_write() and friends safe to use for !CONFIG_BLOCK

Signed-off-by: Jens Axboe

Merge branch 'akpm' (patches from Andrew)

2016-07-27T02:55:54+00:00

Merge updates from Andrew Morton:

 - a few misc bits

 - ocfs2

 - most(?) of MM

* emailed patches from Andrew Morton : (125 commits)
  thp: fix comments of __pmd_trans_huge_lock()
  cgroup: remove unnecessary 0 check from css_from_id()
  cgroup: fix idr leak for the first cgroup root
  mm: memcontrol: fix documentation for compound parameter
  mm: memcontrol: remove BUG_ON in uncharge_list
  mm: fix build warnings in 
  mm, thp: convert from optimistic swapin collapsing to conservative
  mm, thp: fix comment inconsistency for swapin readahead functions
  thp: update Documentation/{vm/transhuge,filesystems/proc}.txt
  shmem: split huge pages beyond i_size under memory pressure
  thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE
  khugepaged: add support of collapse for tmpfs/shmem pages
  shmem: make shmem_inode_info::lock irq-safe
  khugepaged: move up_read(mmap_sem) out of khugepaged_alloc_page()
  thp: extract khugepaged from mm/huge_memory.c
  shmem, thp: respect MADV_{NO,}HUGEPAGE for file mappings
  shmem: add huge pages support
  shmem: get_unmapped_area align huge page
  shmem: prepare huge= mount option and sysfs knob
  mm, rmap: account shmem thp pages
  ...

zram: use __GFP_MOVABLE for memory allocation

2016-07-26T23:19:19+00:00

Zsmalloc is ready for page migration so zram can use __GFP_MOVABLE from
now on.

I did test to see how it helps to make higher order pages.  Test
scenario is as follows.

KVM guest, 1G memory, ext4 formated zram block device,

  for i in `seq 1 8`;
  do
          dd if=/dev/vda1 of=mnt/test$i.txt bs=128M count=1 &
  done

  wait `pidof dd`

  for i in `seq 1 2 8`;
  do
          rm -rf mnt/test$i.txt
  done
  fstrim -v mnt

  echo "init"
  cat /proc/buddyinfo

  echo "compaction"
  echo 1 > /proc/sys/vm/compact_memory
  cat /proc/buddyinfo

old:

  init
  Node 0, zone      DMA    208    120     51     41     11      0      0      0      0      0      0
  Node 0, zone    DMA32  16380  13777   9184   3805    789     54      3      0      0      0      0
  compaction
  Node 0, zone      DMA    132     82     40     39     16      2      1      0      0      0      0
  Node 0, zone    DMA32   5219   5526   4969   3455   1831    677    139     15      0      0      0

new:

  init
  Node 0, zone      DMA    379    115     97     19      2      0      0      0      0      0      0
  Node 0, zone    DMA32  18891  16774  10862   3947    637     21      0      0      0      0      0
  compaction
  Node 0, zone      DMA    214     66     87     29     10      3      0      0      0      0      0
  Node 0, zone    DMA32   1612   3139   3154   2469   1745    990    384     94      7      0      0

As you can see, compaction made so many high-order pages. Yay!

Link: http://lkml.kernel.org/r/1464736881-24886-13-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim 
Reviewed-by: Sergey Senozhatsky 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: drop gfp_t from zcomp_strm_alloc()

2016-07-26T23:19:19+00:00

We now allocate streams from CPU_UP hot-plug path, there are no
context-dependent stream allocations anymore and we can schedule from
zcomp_strm_alloc().  Use GFP_KERNEL directly and drop a gfp_t parameter.

Link: http://lkml.kernel.org/r/20160531122017.2878-9-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky 
Acked-by: Minchan Kim 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: add more compression algorithms

2016-07-26T23:19:19+00:00

Add "deflate", "lz4hc", "842" algorithms to the list of known
compression backends.  The real availability of those algorithms,
however, depends on the corresponding CONFIG_CRYPTO_FOO config options.

[sergey.senozhatsky@gmail.com: zram-add-more-compression-algorithms-v3]
  Link: http://lkml.kernel.org/r/20160604024902.11778-7-sergey.senozhatsky@gmail.com
Link: http://lkml.kernel.org/r/20160531122017.2878-8-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky 
Acked-by: Minchan Kim 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: delete custom lzo/lz4

2016-07-26T23:19:19+00:00

Remove lzo/lz4 backends, we use crypto API now.

[sergey.senozhatsky@gmail.com: zram-delete-custom-lzo-lz4-v3]
  Link: http://lkml.kernel.org/r/20160604024902.11778-6-sergey.senozhatsky@gmail.com
Link: http://lkml.kernel.org/r/20160531122017.2878-7-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky 
Acked-by: Minchan Kim 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: use crypto api to check alg availability

2016-07-26T23:19:19+00:00

There is no way to get a string with all the crypto comp algorithms
supported by the crypto comp engine, so we need to maintain our own
backends list.  At the same time we additionally need to use
crypto_has_comp() to make sure that the user has requested a compression
algorithm that is recognized by the crypto comp engine.  Relying on
/proc/crypto is not an options here, because it does not show
not-yet-inserted compression modules.

Example:

 modprobe zram
 cat /proc/crypto | grep -i lz4
 modprobe lz4
 cat /proc/crypto | grep -i lz4
name         : lz4
driver       : lz4-generic
module       : lz4

So the user can't tell exactly if the lz4 is really supported from
/proc/crypto output, unless someone or something has loaded it.

This patch also adds crypto_has_comp() to zcomp_available_show().  We
store all the compression algorithms names in zcomp's `backends' array,
regardless the CONFIG_CRYPTO_FOO configuration, but show only those that
are also supported by crypto engine.  This helps user to know the exact
list of compression algorithms that can be used.

Example:
  module lz4 is not loaded yet, but is supported by the crypto
  engine. /proc/crypto has no information on this module, while
  zram's `comp_algorithm' lists it:

 cat /proc/crypto | grep -i lz4

 cat /sys/block/zram0/comp_algorithm
[lzo] lz4 deflate lz4hc 842

We still use the `backends' array to determine if the requested
compression backend is known to crypto api.  This array, however, may not
contain some entries, therefore as the last step we call crypto_has_comp()
function which attempts to insmod the requested compression algorithm to
determine if crypto api supports it.  The advantage of this method is that
now we permit the usage of out-of-tree crypto compression modules
(implementing S/W or H/W compression).

[sergey.senozhatsky@gmail.com: zram-use-crypto-api-to-check-alg-availability-v3]
  Link: http://lkml.kernel.org/r/20160604024902.11778-4-sergey.senozhatsky@gmail.com
Link: http://lkml.kernel.org/r/20160531122017.2878-5-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky 
Acked-by: Minchan Kim 
Cc: Joonsoo Kim 
Signed-off-by: Sergey Senozhatsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds