Nothing prevents a dentry found by path lookup before a return of
__debugfs_remove() to actually get opened after that return. Now, after
the return of __debugfs_remove(), there are no guarantees whatsoever
regarding the memory the corresponding inode's file_operations object
had been kept in.

Since __debugfs_remove() is seldomly invoked, usually from module exit
handlers only, the race is hard to trigger and the impact is very low.

A discussion of the problem outlined above as well as a suggested
solution can be found in the (sub-)thread rooted at

  http://lkml.kernel.org/g/20130401203445.GA20862@ZenIV.linux.org.uk
  ("Yet another pipe related oops.")

Basically, Greg KH suggests to introduce an intermediate fops and
Al Viro points out that a pointer to the original ones may be stored in
->d_fsdata.

Follow this line of reasoning:
- Add SRCU as a reverse dependency of DEBUG_FS.
- Introduce a srcu_struct object for the debugfs subsystem.
- In debugfs_create_file(), store a pointer to the original
  file_operations object in ->d_fsdata.
- Make debugfs_remove() and debugfs_remove_recursive() wait for a
  SRCU grace period after the dentry has been delete()'d and before they
  return to their callers.
- Introduce an intermediate file_operations object named
  "debugfs_open_proxy_file_operations". It's ->open() functions checks,
  under the protection of a SRCU read lock, whether the dentry is still
  alive, i.e. has not been d_delete()'d and if so, tries to acquire a
  reference on the owning module.
  On success, it sets the file object's ->f_op to the original
  file_operations and forwards the ongoing open() call to the original
  ->open().
- For clarity, rename the former debugfs_file_operations to
  debugfs_noop_file_operations -- they are in no way canonical.

The choice of SRCU over "normal" RCU is justified by the fact, that the
former may also be used to protect ->i_private data from going away
during the execution of a file's readers and writers which may (and do)
sleep.

Finally, introduce the fs/debugfs/internal.h header containing some
declarations internal to the debugfs implementation.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This is in preparation for the series that transitions
filesystem timestamps to use 64 bit time and hence make
them y2038 safe.

CURRENT_TIME macro will be deleted before merging the
aforementioned series.

Use current_fs_time() instead of CURRENT_TIME for inode
timestamps.

struct kernfs_node is associated with a sysfs file/ directory.
Truncate the values to appropriate time granularity when
writing to inode timestamps of the files.

ktime_get_real_ts() is used to obtain times for
struct kernfs_iattrs. Since these times are later assigned to
inode times using timespec_truncate() for all filesystem based
operations, we can save the supers list traversal time here by
using ktime_get_real_ts() directly.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

CURRENT_TIME macro is not appropriate for filesystems as it
doesn't use the right granularity for filesystem timestamps.
Use current_fs_time() instead.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Directory inodes should start off with i_nlink == 2 (one extra ref
for "." entry).  debugfs_create_automount() increases neither the
i_nlink reference for current inode nor for parent inode.

On attempt to remove the automount dentry, kernel complains:

  [   86.288070] WARNING: CPU: 1 PID: 3616 at fs/inode.c:273 drop_nlink+0x3e/0x50()
  [   86.288461] Modules linked in: debugfs_example2(O-)
  [   86.288745] CPU: 1 PID: 3616 Comm: rmmod Tainted: G           O    4.4.0-rc3-next-20151207+ #135
  [   86.289197] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.2-20150617_082717-anatol 04/01/2014
  [   86.289696]  ffffffff81be05c9 ffff8800b9e6fda0 ffffffff81352e2c 0000000000000000
  [   86.290110]  ffff8800b9e6fdd8 ffffffff81065142 ffff8801399175e8 ffff8800bb78b240
  [   86.290507]  ffff8801399175e8 ffff8800b73d7898 ffff8800b73d7840 ffff8800b9e6fde8
  [   86.290933] Call Trace:
  [   86.291080]  [<ffffffff81352e2c>] dump_stack+0x4e/0x82
  [   86.291340]  [<ffffffff81065142>] warn_slowpath_common+0x82/0xc0
  [   86.291640]  [<ffffffff8106523a>] warn_slowpath_null+0x1a/0x20
  [   86.291932]  [<ffffffff811ae62e>] drop_nlink+0x3e/0x50
  [   86.292208]  [<ffffffff811ba35b>] simple_unlink+0x4b/0x60
  [   86.292481]  [<ffffffff811ba3a7>] simple_rmdir+0x37/0x50
  [   86.292748]  [<ffffffff812d9808>] __debugfs_remove.part.16+0xa8/0xd0
  [   86.293082]  [<ffffffff812d9a0b>] debugfs_remove_recursive+0xdb/0x1c0
  [   86.293406]  [<ffffffffa00004dd>] cleanup_module+0x2d/0x3b [debugfs_example2]
  [   86.293762]  [<ffffffff810d959b>] SyS_delete_module+0x16b/0x220
  [   86.294077]  [<ffffffff818ef857>] entry_SYSCALL_64_fastpath+0x12/0x6a
  [   86.294405] ---[ end trace c9fc53353fe14a36 ]---
  [   86.294639] ------------[ cut here ]------------

To reproduce the issue it is enough to invoke these lines:

     autom = debugfs_create_automount("automount", NULL, vfsmount_cb, data);
     BUG_ON(IS_ERR_OR_NULL(autom));
     debugfs_remove(autom);

The issue is fixed by increasing inode i_nlink references for current
and parent inodes.
Signed-off-by: Roman Pen <r.peniaev@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Many motherboards utilize a LPC to ISA bridge in order to decode
ISA-style port-mapped I/O addresses. This is particularly true for
embedded motherboards supporting the PC/104 bus (a bus specification
derived from ISA).

These motherboards are now commonly running 64-bit x86 processors. The
X86_32 dependency should be removed from the ISA bus configuration
option in order to support these newer motherboards.

A new config option, CONFIG_ISA_BUS, is introduced to allow for the
compilation of the ISA bus driver independent of the CONFIG_ISA option.
Devices which communicate via ISA-compatible buses can now be supported
independent of the dependencies of the CONFIG_ISA option.
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Alan is no longer maintaining this list through the Linux assigned
numbers authority. Make it a collective document by referring to
"the maintainers" in plural throughout, and naming the chardev and
block layer maintainers in particular as parties of involvement.
Cut down and remove some sections that pertained to the process of
maintaining the list at lanana.org and contacting Alan directly.

Make it clear that this document, in the kernel, is the master
document.

Also move paragraphs around so as to emphasize dynamic major number
allocation.

Remove paragraph on 2.6 deprecation, that tag no longer appears
anywhere in the file.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently a dynamically allocated character device major is taken
from 254 and downward. This mechanism is used for RTC, IIO and a
few other subsystems.

The kernel currently has no check prevening these dynamic
allocations from eating into the assigned numbers at 233 and
downward.

In a recent test it was reported that so many dynamic device
majors were used on a test server, that the major number for
infiniband (231) was stolen. This occurred when allocating a new
major number for GPIO chips. The error messages from the kernel
were not helpful. (See: https://lkml.org/lkml/2016/2/14/124)

This patch adds a defined lower limit of the dynamic major
allocation region will henceforth emit a warning if we start to
eat into the assigned numbers. It does not do any semantic
changes and will not change the kernels behaviour: numbers will
still continue to be stolen, but we will know from dmesg what
is going on.

This also updates the Documentation/devices.txt to clearly
reflect that we are using this range of major numbers for dynamic
allocation.
Reported-by: Ying Huang <ying.huang@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Refrain from defining default fw_cfg register offsets on
unsupported architectures -- throw an error instead. If
QEMU were to add fw_cfg support on additional architectures,
we should add them to the FW_CFG_SYSFS depends statement in
drivers/firmware/Kconfig, and provide default values for
register offsets in drivers/firmware/qemu_fw_cfg.c at that
time.
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull Ceph updates from Sage Weil:
 "There is quite a bit here, including some overdue refactoring and
  cleanup on the mon_client and osd_client code from Ilya, scattered
  writeback support for CephFS and a pile of bug fixes from Zheng, and a
  few random cleanups and fixes from others"

[ I already decided not to pull this because of it having been rebased
  recently, but ended up changing my mind after all.  Next time I'll
  really hold people to it.  Oh well.   - Linus ]

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: (34 commits)
  libceph: use KMEM_CACHE macro
  ceph: use kmem_cache_zalloc
  rbd: use KMEM_CACHE macro
  ceph: use lookup request to revalidate dentry
  ceph: kill ceph_get_dentry_parent_inode()
  ceph: fix security xattr deadlock
  ceph: don't request vxattrs from MDS
  ceph: fix mounting same fs multiple times
  ceph: remove unnecessary NULL check
  ceph: avoid updating directory inode's i_size accidentally
  ceph: fix race during filling readdir cache
  libceph: use sizeof_footer() more
  ceph: kill ceph_empty_snapc
  ceph: fix a wrong comparison
  ceph: replace CURRENT_TIME by current_fs_time()
  ceph: scattered page writeback
  libceph: add helper that duplicates last extent operation
  libceph: enable large, variable-sized OSD requests
  libceph: osdc->req_mempool should be backed by a slab pool
  libceph: make r_request msg_size calculation clearer
  ...

Pull orangefs filesystem from Mike Marshall.

This finally merges the long-pending orangefs filesystem, which has been
much cleaned up with input from Al Viro over the last six months.  From
the documentation file:

 "OrangeFS is an LGPL userspace scale-out parallel storage system.  It
  is ideal for large storage problems faced by HPC, BigData, Streaming
  Video, Genomics, Bioinformatics.

  Orangefs, originally called PVFS, was first developed in 1993 by Walt
  Ligon and Eric Blumer as a parallel file system for Parallel Virtual
  Machine (PVM) as part of a NASA grant to study the I/O patterns of
  parallel programs.

  Orangefs features include:

    - Distributes file data among multiple file servers
    - Supports simultaneous access by multiple clients
    - Stores file data and metadata on servers using local file system
      and access methods
    - Userspace implementation is easy to install and maintain
    - Direct MPI support
    - Stateless"

see Documentation/filesystems/orangefs.txt for more in-depth details.

* tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux: (174 commits)
  orangefs: fix orangefs_superblock locking
  orangefs: fix do_readv_writev() handling of error halfway through
  orangefs: have ->kill_sb() evict the VFS side of things first
  orangefs: sanitize ->llseek()
  orangefs-bufmap.h: trim unused junk
  orangefs: saner calling conventions for getting a slot
  orangefs_copy_{to,from}_bufmap(): don't pass bufmap pointer
  orangefs: get rid of readdir_handle_s
  ornagefs: ensure that truncate has an up to date inode size
  orangefs: move code which sets i_link to orangefs_inode_getattr
  orangefs: remove needless wrapper around GFP_KERNEL
  orangefs: remove wrapper around mutex_lock(&inode->i_mutex)
  orangefs: refactor inode type or link_target change detection
  orangefs: use new getattr for revalidate and remove old getattr
  orangefs: use new getattr in inode getattr and permission
  orangefs: use new orangefs_inode_getattr to get size in write and llseek
  orangefs: use new orangefs_inode_getattr to create new inodes
  orangefs: rename orangefs_inode_getattr to orangefs_inode_old_getattr
  orangefs: remove inode->i_lock wrapper
  orangefs: put register_chrdev immediately before register_filesystem
  ...

Pull NTB bug fixes from Jon Mason:
 "NTB bug fixes for tasklet from spinning forever, link errors,
  translation window setup, NULL ptr dereference, and ntb-perf errors.

  Also, a modification to the driver API that makes _addr functions
  optional"

* tag 'ntb-4.6' of git://github.com/jonmason/ntb:
  NTB: Remove _addr functions from ntb_hw_amd
  NTB: Make _addr functions optional in the API
  NTB: Fix incorrect clean up routine in ntb_perf
  NTB: Fix incorrect return check in ntb_perf
  ntb: fix possible NULL dereference
  ntb: add missing setup of translation window
  ntb: stop link work when we do not have memory
  ntb: stop tasklet from spinning forever during shutdown.
  ntb: perf test: fix address space confusion

Pull more SCSI updates from James Bottomley:
 "The only new stuff which missed the first pull request is an update to
  the UFS driver.

  The rest is an assortment of bug fixes and minor tweaks which appeared
  recently (some are fixes for recent code and some are stuff spotted
  recently by the checkers or the new gcc-6 compiler [most of Arnd's
  stuff])"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (32 commits)
  scsi_common: do not clobber fixed sense information
  scsi: ufs: select CONFIG_NLS
  scsi: fc: use get/put_unaligned64 for wwn access
  fnic: move printk()s outside of the critical code section.
  qla2xxx: avoid maybe_uninitialized warning
  megaraid_sas: add missing curly braces in ioctl handler
  lpfc: fix misleading indentation
  scsi_transport_sas: add 'scsi_target_id' sysfs attribute
  scsi_dh_alua: uninitialized variable in alua_check_vpd()
  scsi: ufs-qcom: add printouts of testbus debug registers
  scsi: ufs-qcom: enable/disable the device ref clock
  scsi: ufs-qcom: set PA_Local_TX_LCC_Enable before link startup
  scsi: ufs: add device quirk delay before putting UFS rails in LPM
  scsi: ufs: fix leakage during link off state
  scsi: ufs: tune UniPro parameters to optimize hibern8 exit time
  scsi: ufs: handle non spec compliant bkops behaviour by device
  scsi: ufs: add retry for query descriptors
  scsi: ufs: add error recovery after DL NAC error
  scsi: ufs: make error handling bit faster
  scsi: ufs: disable vccq if it's not needed by UFS device
  ...

Commit 0b81d077 ("fs crypto: move per-file encryption from f2fs
tree to fs/crypto") moved the f2fs crypto files to fs/crypto/ and
renamed the symbol prefixes from "f2fs_" to "fscrypt_" (and from "F2FS_"
to just "FS" for preprocessor symbols).

Because of the symbol renaming, it's a bit hard to see it as a file
move: use

    git show -M30 0b81d077

to lower the rename detection to just 30% similarity and make git show
the files as renamed (the header file won't be shown as a rename even
then - since all it contains is symbol definitions, it looks almost
completely different).

Even with the renames showing as renames, the diffs are not all that
easy to read, since so much is just the renames.  But Eric Biggers
noticed that it's not just all renames: the initialization of the
xts_tweak had been broken too, using the inode number rather than the
page offset.

That's not right - it makes the xfs_tweak the same for all pages of each
inode.  It _might_ make sense to make the xfs_tweak contain both the
offset _and_ the inode number, but not just the inode number.
Reported-by: Eric Biggers <ebiggers3@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Kernel zero day testing warned about address space confusion.  A virtual
iomem address was used where a physical address is expected.  The
offending functions implement an optional part of the api, so they are
removed.  They can be added later, after testing.

Fixes: a1b36958Signed-off-by: Allen Hubbe <Allen.Hubbe@emc.com>
Acked-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

* switch orangefs_remount() to taking ORANGEFS_SB(sb) instead of sb
* remove from the list _before_ orangefs_unmount() - request_mutex
in the latter will make sure that nothing observed in the loop in
ORANGEFS_DEV_REMOUNT_ALL handling will get freed until the end
of loop
* on removal, keep the forward pointer and zero the back one.  That
way we can drop and regain the spinlock in the loop body (again,
ORANGEFS_DEV_REMOUNT_ALL one) and still be able to get to the
rest of the list.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Error should only be returned if nothing had been read/written.
Otherwise we need to report a short read/write instead.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

a) open files can't have NULL inodes
b) it's SEEK_END, not ORANGEFS_SEEK_END; no need to get cute.
c) make_bad_inode() on lseek()?
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

just have it return the slot number or -E... - the caller checks
the sign anyway
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

it's always __orangefs_bufmap
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

no point, really - we couldn't keep those across the calls of
getdents(); it would be too easy to DoS, having all slots exhausted.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Merge fourth patch-bomb from Andrew Morton:
 "A lot more stuff than expected, sorry.  A bunch of ocfs2 reviewing was
  finished off.

   - mhocko's oom-reaper out-of-memory-handler changes

   - ocfs2 fixes and features

   - KASAN feature work

   - various fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (42 commits)
  thp: fix typo in khugepaged_scan_pmd()
  MAINTAINERS: fill entries for KASAN
  mm/filemap: generic_file_read_iter(): check for zero reads unconditionally
  kasan: test fix: warn if the UAF could not be detected in kmalloc_uaf2
  mm, kasan: stackdepot implementation. Enable stackdepot for SLAB
  arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections
  mm, kasan: add GFP flags to KASAN API
  mm, kasan: SLAB support
  kasan: modify kmalloc_large_oob_right(), add kmalloc_pagealloc_oob_right()
  include/linux/oom.h: remove undefined oom_kills_count()/note_oom_kill()
  mm/page_alloc: prevent merging between isolated and other pageblocks
  drivers/memstick/host/r592.c: avoid gcc-6 warning
  ocfs2: extend enough credits for freeing one truncate record while replaying truncate records
  ocfs2: extend transaction for ocfs2_remove_rightmost_path() and ocfs2_update_edge_lengths() before to avoid inconsistency between inode and et
  ocfs2/dlm: move lock to the tail of grant queue while doing in-place convert
  ocfs2: solve a problem of crossing the boundary in updating backups
  ocfs2: fix occurring deadlock by changing ocfs2_wq from global to local
  ocfs2/dlm: fix BUG in dlm_move_lockres_to_recovery_list
  ocfs2/dlm: fix race between convert and recovery
  ocfs2: fix a deadlock issue in ocfs2_dio_end_io_write()
  ...

Pull power management fixlet from Rafael Wysocki:
 "One of commits in my previous pull request changed the permissions of
  drivers/power/avs/rockchip-io-domain.c to executable by mistake"

* tag 'pm+acpi-4.6-rc1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Fix permissions of drivers/power/avs/rockchip-io-domain.c

Pull ia64 update from Tony Luck:
 "Wire up new system calls p{read,write}v2 for ia64"

* tag 'please-pull-preadv2' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  [IA64] Enable preadv2 and pwritev2 syscalls for ia64

Pull more input updates from Dmitry Torokhov:
 "Second round of updates for the input subsystem.

  The BYD PS/2 protocol driver now uses absolute reporting mode and
  should behave more like other touchpads; Synaptics driver needed to
  extend one of its quirks to a newer firmware version, and a few USB
  drivers got tightened up checks for the contents of their descriptors"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: sur40 - fix DMA on stack
  Input: ati_remote2 - fix crashes on detecting device with invalid descriptor
  Input: synaptics - handle spurious release of trackstick buttons, again
  Input: synaptics-rmi4 - remove check of Non-NULL array
  Input: byd - enable absolute mode
  Input: ims-pcu - sanity check against missing interfaces
  Input: melfas_mip4 - add hw_version sysfs attribute

!PageLRU should lead to SCAN_PAGE_LRU, not SCAN_SCAN_ABORT result.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If
 - generic_file_read_iter() gets called with a zero read length,
 - the read offset is at a page boundary,
 - IOCB_DIRECT is not set
-  and the page in question hasn't made it into the page cache yet,
then do_generic_file_read() will trigger a readahead with a req_size hint
of zero.

Since roundup_pow_of_two(0) is undefined, UBSAN reports

  UBSAN: Undefined behaviour in include/linux/log2.h:63:13
  shift exponent 64 is too large for 64-bit type 'long unsigned int'
  CPU: 3 PID: 1017 Comm: sa1 Tainted: G L 4.5.0-next-20160318+ #14
  [...]
  Call Trace:
   [...]
   [<ffffffff813ef61a>] ondemand_readahead+0x3aa/0x3d0
   [<ffffffff813ef61a>] ? ondemand_readahead+0x3aa/0x3d0
   [<ffffffff813c73bd>] ? find_get_entry+0x2d/0x210
   [<ffffffff813ef9c3>] page_cache_sync_readahead+0x63/0xa0
   [<ffffffff813cc04d>] do_generic_file_read+0x80d/0xf90
   [<ffffffff813cc955>] generic_file_read_iter+0x185/0x420
   [...]
   [<ffffffff81510b06>] __vfs_read+0x256/0x3d0
   [...]

when get_init_ra_size() gets called from ondemand_readahead().

The net effect is that the initial readahead size is arch dependent for
requested read lengths of zero: for example, since

  1UL << (sizeof(unsigned long) * 8)

evaluates to 1 on x86 while its result is 0 on ARMv7, the initial readahead
size becomes 4 on the former and 0 on the latter.

What's more, whether or not the file access timestamp is updated for zero
length reads is decided differently for the two cases of IOCB_DIRECT
being set or cleared: in the first case, generic_file_read_iter()
explicitly skips updating that timestamp while in the latter case, it is
always updated through the call to do_generic_file_read().

According to POSIX, zero length reads "do not modify the last data access
timestamp" and thus, the IOCB_DIRECT behaviour is POSIXly correct.

Let generic_file_read_iter() unconditionally check the requested read
length at its entry and return immediately with success if it is zero.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Implement the stack depot and provide CONFIG_STACKDEPOT.  Stack depot
will allow KASAN store allocation/deallocation stack traces for memory
chunks.  The stack traces are stored in a hash table and referenced by
handles which reside in the kasan_alloc_meta and kasan_free_meta
structures in the allocated memory chunks.

IRQ stack traces are cut below the IRQ entry point to avoid unnecessary
duplication.

Right now stackdepot support is only enabled in SLAB allocator.  Once
KASAN features in SLAB are on par with those in SLUB we can switch SLUB
to stackdepot as well, thus removing the dependency on SLUB stack
bookkeeping, which wastes a lot of memory.

This patch is based on the "mm: kasan: stack depots" patch originally
prepared by Dmitry Chernenkov.

Joonsoo has said that he plans to reuse the stackdepot code for the
mm/page_owner.c debugging facility.

[akpm@linux-foundation.org: s/depot_stack_handle/depot_stack_handle_t]
[aryabinin@virtuozzo.com: comment style fixes]
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

KASAN needs to know whether the allocation happens in an IRQ handler.
This lets us strip everything below the IRQ entry point to reduce the
number of unique stack traces needed to be stored.

Move the definition of __irq_entry to <linux/interrupt.h> so that the
users don't need to pull in <linux/ftrace.h>.  Also introduce the
__softirq_entry macro which is similar to __irq_entry, but puts the
corresponding functions to the .softirqentry.text section.
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add GFP flags to KASAN hooks for future patches to use.

This patch is based on the "mm: kasan: unified support for SLUB and SLAB
allocators" patch originally prepared by Dmitry Chernenkov.
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add KASAN hooks to SLAB allocator.

This patch is based on the "mm: kasan: unified support for SLUB and SLAB
allocators" patch originally prepared by Dmitry Chernenkov.
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This patchset implements SLAB support for KASAN

Unlike SLUB, SLAB doesn't store allocation/deallocation stacks for heap
objects, therefore we reimplement this feature in mm/kasan/stackdepot.c.
The intention is to ultimately switch SLUB to use this implementation as
well, which will save a lot of memory (right now SLUB bloats each object
by 256 bytes to store the allocation/deallocation stacks).

Also neither SLUB nor SLAB delay the reuse of freed memory chunks, which
is necessary for better detection of use-after-free errors.  We
introduce memory quarantine (mm/kasan/quarantine.c), which allows
delayed reuse of deallocated memory.

This patch (of 7):

Rename kmalloc_large_oob_right() to kmalloc_pagealloc_oob_right(), as
the test only checks the page allocator functionality.  Also reimplement
kmalloc_large_oob_right() so that the test allocates a large enough
chunk of memory that still does not trigger the page allocator fallback.
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A leftover from commit c32b3cbe ("oom, PM: make OOM detection in the
freezer path raceless").
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Hanjun Guo has reported that a CMA stress test causes broken accounting of
CMA and free pages:

> Before the test, I got:
> -bash-4.3# cat /proc/meminfo | grep Cma
> CmaTotal:         204800 kB
> CmaFree:          195044 kB
>
>
> After running the test:
> -bash-4.3# cat /proc/meminfo | grep Cma
> CmaTotal:         204800 kB
> CmaFree:         6602584 kB
>
> So the freed CMA memory is more than total..
>
> Also the the MemFree is more than mem total:
>
> -bash-4.3# cat /proc/meminfo
> MemTotal:       16342016 kB
> MemFree:        22367268 kB
> MemAvailable:   22370528 kB

Laura Abbott has confirmed the issue and suspected the freepage accounting
rewrite around 3.18/4.0 by Joonsoo Kim.  Joonsoo had a theory that this is
caused by unexpected merging between MIGRATE_ISOLATE and MIGRATE_CMA
pageblocks:

> CMA isolates MAX_ORDER aligned blocks, but, during the process,
> partialy isolated block exists. If MAX_ORDER is 11 and
> pageblock_order is 9, two pageblocks make up MAX_ORDER
> aligned block and I can think following scenario because pageblock
> (un)isolation would be done one by one.
>
> (each character means one pageblock. 'C', 'I' means MIGRATE_CMA,
> MIGRATE_ISOLATE, respectively.
>
> CC -> IC -> II (Isolation)
> II -> CI -> CC (Un-isolation)
>
> If some pages are freed at this intermediate state such as IC or CI,
> that page could be merged to the other page that is resident on
> different type of pageblock and it will cause wrong freepage count.

This was supposed to be prevented by CMA operating on MAX_ORDER blocks,
but since it doesn't hold the zone->lock between pageblocks, a race
window does exist.

It's also likely that unexpected merging can occur between
MIGRATE_ISOLATE and non-CMA pageblocks.  This should be prevented in
__free_one_page() since commit 3c605096 ("mm/page_alloc: restrict
max order of merging on isolated pageblock").  However, we only check
the migratetype of the pageblock where buddy merging has been initiated,
not the migratetype of the buddy pageblock (or group of pageblocks)
which can be MIGRATE_ISOLATE.

Joonsoo has suggested checking for buddy migratetype as part of
page_is_buddy(), but that would add extra checks in allocator hotpath
and bloat-o-meter has shown significant code bloat (the function is
inline).

This patch reduces the bloat at some expense of more complicated code.
The buddy-merging while-loop in __free_one_page() is initially bounded
to pageblock_border and without any migratetype checks.  The checks are
placed outside, bumping the max_order if merging is allowed, and
returning to the while-loop with a statement which can't be possibly
considered harmful.

This fixes the accounting bug and also removes the arguably weird state
in the original commit 3c605096 where buddies could be left
unmerged.

Fixes: 3c605096 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
Link: https://lkml.org/lkml/2016/3/2/280Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Hanjun Guo <guohanjun@huawei.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Debugged-by: Laura Abbott <labbott@redhat.com>
Debugged-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>	[3.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The r592 driver relies on behavior of the DMA mapping API that is
normally observed but not guaranteed by the API.  Instead it uses a
runtime check to fail transfers if the API ever behaves

When CONFIG_NEED_SG_DMA_LENGTH is not set, one of the checks turns into a
comparison of a variable with itself, which gcc-6.0 now warns about:

drivers/memstick/host/r592.c: In function 'r592_transfer_fifo_dma':
drivers/memstick/host/r592.c:302:31: error: self-comparison always evaluates to false [-Werror=tautological-compare]
    (sg_dma_len(&dev->req->sg) < dev->req->sg.length)) {
                               ^

The check itself is not a problem, so this patch just rephrases the
condition in a way that gcc does not consider an indication of a mistake.
We already know that dev->req->sg.length was initially R592_LFIFO_SIZE, so
we can compare it to that constant again.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Quentin Lambert <lambert.quentin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Now function ocfs2_replay_truncate_records() first modifies tl_used,
then calls ocfs2_extend_trans() to extend transactions for gd and alloc
inode used for freeing clusters.  jbd2_journal_restart() may be called
and it may happen that tl_used in truncate log is decreased but the
clusters are not freed, which means these clusters are lost.  So we
should avoid extending transactions in these two operations.
Signed-off-by: joyce.xue <xuejiufei@huawei.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Acked-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>