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  1. 07 7月, 2018 4 次提交
  3. 06 7月, 2018 1 次提交
  5. 05 7月, 2018 2 次提交
  7. 03 7月, 2018 4 次提交
    • D
      dma-fence: Make ->wait callback optional · 418cc6ca
      由 Daniel Vetter 提交于 
      Almost everyone uses dma_fence_default_wait.

v2: Also remove the BUG_ON(!ops->wait) (Chris).

Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20180503142603.28513-5-daniel.vetter@ffwll.ch
      418cc6ca
    • T
      locking: Implement an algorithm choice for Wound-Wait mutexes · 08295b3b
      由 Thomas Hellstrom 提交于 
      The current Wound-Wait mutex algorithm is actually not Wound-Wait but
Wait-Die. Implement also Wound-Wait as a per-ww-class choice. Wound-Wait
is, contrary to Wait-Die a preemptive algorithm and is known to generate
fewer backoffs. Testing reveals that this is true if the
number of simultaneous contending transactions is small.
As the number of simultaneous contending threads increases, Wait-Wound
becomes inferior to Wait-Die in terms of elapsed time.
Possibly due to the larger number of held locks of sleeping transactions.

Update documentation and callers.

Timings using git://people.freedesktop.org/~thomash/ww_mutex_test
tag patch-18-06-15

Each thread runs 100000 batches of lock / unlock 800 ww mutexes randomly
chosen out of 100000. Four core Intel x86_64:

Algorithm    #threads       Rollbacks  time
Wound-Wait   4              ~100       ~17s.
Wait-Die     4              ~150000    ~19s.
Wound-Wait   16             ~360000    ~109s.
Wait-Die     16             ~450000    ~82s.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Co-authored-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NThomas Hellstrom <thellstrom@vmware.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NIngo Molnar <mingo@kernel.org>
      08295b3b
    • P
      locking: WW mutex cleanup · 55f036ca
      由 Peter Ziljstra 提交于 
      Make the WW mutex code more readable by adding comments, splitting up
functions and pointing out that we're actually using the Wait-Die
algorithm.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Co-authored-by: NThomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Hellstrom <thellstrom@vmware.com>
Acked-by: NIngo Molnar <mingo@kernel.org>
      55f036ca
    • R
      drm: add missing ctx argument to plane transitional helpers · 070473bc
      由 Russell King 提交于 
      In commits:
34a2ab5e ("drm: Add acquire ctx parameter to ->update_plane")
19315294 ("drm: Add acquire ctx parameter to ->plane_disable")

a pointer to a drm_modeset_acquire_ctx structure was added as an
argument to the method prototypes.  The transitional helpers are
supposed to be directly plugged in as implementations of these
methods, but doing so generates a warning.  Add the missing
argument.

A number of buggy users were added for drm_plane_helper_disable()
which need to be fixed up for this change, which we do by passing
a NULL ctx argument.

Fixes: 19315294 ("drm: Add acquire ctx parameter to ->plane_disable")
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/E1fa1Zr-0005gT-VF@rmk-PC.armlinux.org.uk
      070473bc
  9. 02 7月, 2018 5 次提交
  11. 30 6月, 2018 1 次提交
  13. 29 6月, 2018 5 次提交
    • J
      sg: remove ->sg_magic member · 9544bc53
      由 Jens Axboe 提交于 
      This was introduced more than a decade ago when sg chaining was
added, but we never really caught anything with it. The scatterlist
entry size can be critical, since drivers allocate it, so remove
the magic member. Recently it's been triggering allocation stalls
and failures in NVMe.
Tested-by: NJordan Glover <Golden_Miller83@protonmail.ch>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      9544bc53
    • A
      aio: mark __aio_sigset::sigmask const · 2cd3ae21
      由 Avi Kivity 提交于 
      io_pgetevents() will not change the signal mask.  Mark it const to make
it clear and to reduce the need for casts in user code.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAvi Kivity <avi@scylladb.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
[hch: reapply the patch that got incorrectly reverted]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2cd3ae21
    • S
      include/linux/dax.h: dax_iomap_fault() returns vm_fault_t · f77bc3a8
      由 Souptick Joarder 提交于 
      Commit 1c8f4220 ("mm: change return type to vm_fault_t") missed a
conversion.  It's not a big problem at present because mainline is still
using

	typedef int vm_fault_t;

Fixes: 1c8f4220 ("mm: change return type to vm_fault_t")
Link: http://lkml.kernel.org/r/20180620172046.GA27894@jordon-HP-15-Notebook-PCSigned-off-by: NSouptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f77bc3a8
    • M
      slub: fix failure when we delete and create a slab cache · d50d82fa
      由 Mikulas Patocka 提交于 
      In kernel 4.17 I removed some code from dm-bufio that did slab cache
merging (commit 21bb1327: "dm bufio: remove code that merges slab
caches") - both slab and slub support merging caches with identical
attributes, so dm-bufio now just calls kmem_cache_create and relies on
implicit merging.

This uncovered a bug in the slub subsystem - if we delete a cache and
immediatelly create another cache with the same attributes, it fails
because of duplicate filename in /sys/kernel/slab/.  The slub subsystem
offloads freeing the cache to a workqueue - and if we create the new
cache before the workqueue runs, it complains because of duplicate
filename in sysfs.

This patch fixes the bug by moving the call of kobject_del from
sysfs_slab_remove_workfn to shutdown_cache.  kobject_del must be called
while we hold slab_mutex - so that the sysfs entry is deleted before a
cache with the same attributes could be created.

Running device-mapper-test-suite with:

  dmtest run --suite thin-provisioning -n /commit_failure_causes_fallback/

triggered:

  Buffer I/O error on dev dm-0, logical block 1572848, async page read
  device-mapper: thin: 253:1: metadata operation 'dm_pool_alloc_data_block' failed: error = -5
  device-mapper: thin: 253:1: aborting current metadata transaction
  sysfs: cannot create duplicate filename '/kernel/slab/:a-0000144'
  CPU: 2 PID: 1037 Comm: kworker/u48:1 Not tainted 4.17.0.snitm+ #25
  Hardware name: Supermicro SYS-1029P-WTR/X11DDW-L, BIOS 2.0a 12/06/2017
  Workqueue: dm-thin do_worker [dm_thin_pool]
  Call Trace:
   dump_stack+0x5a/0x73
   sysfs_warn_dup+0x58/0x70
   sysfs_create_dir_ns+0x77/0x80
   kobject_add_internal+0xba/0x2e0
   kobject_init_and_add+0x70/0xb0
   sysfs_slab_add+0xb1/0x250
   __kmem_cache_create+0x116/0x150
   create_cache+0xd9/0x1f0
   kmem_cache_create_usercopy+0x1c1/0x250
   kmem_cache_create+0x18/0x20
   dm_bufio_client_create+0x1ae/0x410 [dm_bufio]
   dm_block_manager_create+0x5e/0x90 [dm_persistent_data]
   __create_persistent_data_objects+0x38/0x940 [dm_thin_pool]
   dm_pool_abort_metadata+0x64/0x90 [dm_thin_pool]
   metadata_operation_failed+0x59/0x100 [dm_thin_pool]
   alloc_data_block.isra.53+0x86/0x180 [dm_thin_pool]
   process_cell+0x2a3/0x550 [dm_thin_pool]
   do_worker+0x28d/0x8f0 [dm_thin_pool]
   process_one_work+0x171/0x370
   worker_thread+0x49/0x3f0
   kthread+0xf8/0x130
   ret_from_fork+0x35/0x40
  kobject_add_internal failed for :a-0000144 with -EEXIST, don't try to register things with the same name in the same directory.
  kmem_cache_create(dm_bufio_buffer-16) failed with error -17

Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1806151817130.6333@file01.intranet.prod.int.rdu2.redhat.comSigned-off-by: NMikulas Patocka <mpatocka@redhat.com>
Reported-by: NMike Snitzer <snitzer@redhat.com>
Tested-by: NMike Snitzer <snitzer@redhat.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: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d50d82fa
    • L
      Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL · a11e1d43
      由 Linus Torvalds 提交于 
      The poll() changes were not well thought out, and completely
unexplained.  They also caused a huge performance regression, because
"->poll()" was no longer a trivial file operation that just called down
to the underlying file operations, but instead did at least two indirect
calls.

Indirect calls are sadly slow now with the Spectre mitigation, but the
performance problem could at least be largely mitigated by changing the
"->get_poll_head()" operation to just have a per-file-descriptor pointer
to the poll head instead.  That gets rid of one of the new indirections.

But that doesn't fix the new complexity that is completely unwarranted
for the regular case.  The (undocumented) reason for the poll() changes
was some alleged AIO poll race fixing, but we don't make the common case
slower and more complex for some uncommon special case, so this all
really needs way more explanations and most likely a fundamental
redesign.

[ This revert is a revert of about 30 different commits, not reverted
  individually because that would just be unnecessarily messy  - Linus ]

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a11e1d43
  15. 28 6月, 2018 3 次提交
  17. 27 6月, 2018 1 次提交
  19. 25 6月, 2018 5 次提交
    • A
      disable -Wattribute-alias warning for SYSCALL_DEFINEx() · bee20031
      由 Arnd Bergmann 提交于 
      gcc-8 warns for every single definition of a system call entry
point, e.g.:

include/linux/compat.h:56:18: error: 'compat_sys_rt_sigprocmask' alias between functions of incompatible types 'long int(int,  compat_sigset_t *, compat_sigset_t *, compat_size_t)' {aka 'long int(int,  struct <anonymous> *, struct <anonymous> *, unsigned int)'} and 'long int(long int,  long int,  long int,  long int)' [-Werror=attribute-alias]
  asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))\
                  ^~~~~~~~~~
include/linux/compat.h:45:2: note: in expansion of macro 'COMPAT_SYSCALL_DEFINEx'
  COMPAT_SYSCALL_DEFINEx(4, _##name, __VA_ARGS__)
  ^~~~~~~~~~~~~~~~~~~~~~
kernel/signal.c:2601:1: note: in expansion of macro 'COMPAT_SYSCALL_DEFINE4'
 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
 ^~~~~~~~~~~~~~~~~~~~~~
include/linux/compat.h:60:18: note: aliased declaration here
  asmlinkage long compat_SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__))\
                  ^~~~~~~~~~

The new warning seems reasonable in principle, but it doesn't
help us here, since we rely on the type mismatch to sanitize the
system call arguments. After I reported this as GCC PR82435, a new
-Wno-attribute-alias option was added that could be used to turn the
warning off globally on the command line, but I'd prefer to do it a
little more fine-grained.

Interestingly, turning a warning off and on again inside of
a single macro doesn't always work, in this case I had to add
an extra statement inbetween and decided to copy the __SC_TEST
one from the native syscall to the compat syscall macro.  See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83256 for more details
about this.

[paul.burton@mips.com:
  - Rebase atop current master.
  - Split GCC & version arguments to __diag_ignore() in order to match
    changes to the preceding patch.
  - Add the comment argument to match the preceding patch.]

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82435Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NPaul Burton <paul.burton@mips.com>
Tested-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Tested-by: NStafford Horne <shorne@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
      bee20031
    • A
      kbuild: add macro for controlling warnings to linux/compiler.h · 8793bb7f
      由 Arnd Bergmann 提交于 
      I have occasionally run into a situation where it would make sense to
control a compiler warning from a source file rather than doing so from
a Makefile using the $(cc-disable-warning, ...) or $(cc-option, ...)
helpers.

The approach here is similar to what glibc uses, using __diag() and
related macros to encapsulate a _Pragma("GCC diagnostic ...") statement
that gets turned into the respective "#pragma GCC diagnostic ..." by
the preprocessor when the macro gets expanded.

Like glibc, I also have an argument to pass the affected compiler
version, but decided to actually evaluate that one. For now, this
supports GCC_4_6, GCC_4_7, GCC_4_8, GCC_4_9, GCC_5, GCC_6, GCC_7,
GCC_8 and GCC_9. Adding support for CLANG_5 and other interesting
versions is straightforward here. GNU compilers starting with gcc-4.2
could support it in principle, but "#pragma GCC diagnostic push"
was only added in gcc-4.6, so it seems simpler to not deal with those
at all. The same versions show a large number of warnings already,
so it seems easier to just leave it at that and not do a more
fine-grained control for them.

The use cases I found so far include:

- turning off the gcc-8 -Wattribute-alias warning inside of the
  SYSCALL_DEFINEx() macro without having to do it globally.

- Reducing the build time for a simple re-make after a change,
  once we move the warnings from ./Makefile and
  ./scripts/Makefile.extrawarn into linux/compiler.h

- More control over the warnings based on other configurations,
  using preprocessor syntax instead of Makefile syntax. This should make
  it easier for the average developer to understand and change things.

- Adding an easy way to turn the W=1 option on unconditionally
  for a subdirectory or a specific file. This has been requested
  by several developers in the past that want to have their subsystems
  W=1 clean.

- Integrating clang better into the build systems. Clang supports
  more warnings than GCC, and we probably want to classify them
  as default, W=1, W=2 etc, but there are cases in which the
  warnings should be classified differently due to excessive false
  positives from one or the other compiler.

- Adding a way to turn the default warnings into errors (e.g. using
  a new "make E=0" tag) while not also turning the W=1 warnings into
  errors.

This patch for now just adds the minimal infrastructure in order to
do the first of the list above. As the #pragma GCC diagnostic
takes precedence over command line options, the next step would be
to convert a lot of the individual Makefiles that set nonstandard
options to use __diag() instead.

[paul.burton@mips.com:
  - Rebase atop current master.
  - Add __diag_GCC, or more generally __diag_<compiler>, abstraction to
    avoid code outside of linux/compiler-gcc.h needing to duplicate
    knowledge about different GCC versions.
  - Add a comment argument to __diag_{ignore,warn,error} which isn't
    used in the expansion of the macros but serves to push people to
    document the reason for using them - per feedback from Kees Cook.
  - Translate severity to GCC-specific pragmas in linux/compiler-gcc.h
    rather than using GCC-specific in linux/compiler_types.h.
  - Drop all but GCC 8 macros, since we only need to define macros for
    versions that we need to introduce pragmas for, and as of this
    series that's just GCC 8.
  - Capitalize comments in linux/compiler-gcc.h to match the style of
    the rest of the file.
  - Line up macro definitions with tabs in linux/compiler-gcc.h.]
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NPaul Burton <paul.burton@mips.com>
Tested-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Tested-by: NStafford Horne <shorne@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
      8793bb7f
    • H
      acpi: Add helper for deactivating memory region · d2d2e3c4
      由 Heikki Krogerus 提交于 
      Sometimes memory resource may be overlapping with
SystemMemory Operation Region by design, for example if the
memory region is used as a mailbox for communication with a
firmware in the system. One occasion of such mailboxes is
USB Type-C Connector System Software Interface (UCSI).

With regions like that, it is important that the driver is
able to map the memory with the requirements it has. For
example, the driver should be allowed to map the memory as
non-cached memory. However, if the operation region has been
accessed before the driver has mapped the memory, the memory
has been marked as write-back by the time the driver is
loaded. That means the driver will fail to map the memory
if it expects non-cached memory.

To work around the problem, introducing helper that the
drivers can use to temporarily deactivate (unmap)
SystemMemory Operation Regions that overlap with their
IO memory.

Fixes: 8243edf4 ("usb: typec: ucsi: Add ACPI driver")
Cc: stable@vger.kernel.org
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d2d2e3c4
    • V
      PM / Domains: Rename opp_node to np · ad6384ba
      由 Viresh Kumar 提交于 
      The DT node passed here isn't necessarily an OPP node, as this routine
can also be used for cases where the "required-opps" property is present
directly in the device's node. Rename it.

This also removes a stale comment.
Acked-by: NUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      ad6384ba
    • V
      PM / Domains: Fix return value of of_genpd_opp_to_performance_state() · 5e03aa61
      由 Viresh Kumar 提交于 
      of_genpd_opp_to_performance_state() should return 0 for errors, but the
dummy routine isn't doing that. Fix it.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Acked-by: NUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      5e03aa61
  21. 24 6月, 2018 1 次提交
  23. 23 6月, 2018 3 次提交
    • E
      drm: Consider drivers setting DRIVER_ATOMIC as atomic. · 46d8f405
      由 Eric Anholt 提交于 
      Drivers such as vc4 don't initialize mode_config.funcs until later in
initialization, but we know they're atomic since they've got the flag
set.  This avoids oopsing on dereferencing funcs in the new atomic
methods sanity checks.

I moved the atomic check function down below the core flag check, to
avoid needing a prototype.
Signed-off-by: NEric Anholt <eric@anholt.net>
Fixes: ba1f665f ("drm: Add checks for atomic_[duplicate/destroy]_state with atomic drivers")
Link: https://patchwork.freedesktop.org/patch/msgid/20180621195428.17447-1-eric@anholt.netReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      46d8f405
    • J
      bdi: Fix another oops in wb_workfn() · 3ee7e869
      由 Jan Kara 提交于 
      syzbot is reporting NULL pointer dereference at wb_workfn() [1] due to
wb->bdi->dev being NULL. And Dmitry confirmed that wb->state was
WB_shutting_down after wb->bdi->dev became NULL. This indicates that
unregister_bdi() failed to call wb_shutdown() on one of wb objects.

The problem is in cgwb_bdi_unregister() which does cgwb_kill() and thus
drops bdi's reference to wb structures before going through the list of
wbs again and calling wb_shutdown() on each of them. This way the loop
iterating through all wbs can easily miss a wb if that wb has already
passed through cgwb_remove_from_bdi_list() called from wb_shutdown()
from cgwb_release_workfn() and as a result fully shutdown bdi although
wb_workfn() for this wb structure is still running. In fact there are
also other ways cgwb_bdi_unregister() can race with
cgwb_release_workfn() leading e.g. to use-after-free issues:

CPU1                            CPU2
                                cgwb_bdi_unregister()
                                  cgwb_kill(*slot);

cgwb_release()
  queue_work(cgwb_release_wq, &wb->release_work);
cgwb_release_workfn()
                                  wb = list_first_entry(&bdi->wb_list, ...)
                                  spin_unlock_irq(&cgwb_lock);
  wb_shutdown(wb);
  ...
  kfree_rcu(wb, rcu);
                                  wb_shutdown(wb); -> oops use-after-free

We solve these issues by synchronizing writeback structure shutdown from
cgwb_bdi_unregister() with cgwb_release_workfn() using a new mutex. That
way we also no longer need synchronization using WB_shutting_down as the
mutex provides it for CONFIG_CGROUP_WRITEBACK case and without
CONFIG_CGROUP_WRITEBACK wb_shutdown() can be called only once from
bdi_unregister().
Reported-by: Nsyzbot <syzbot+4a7438e774b21ddd8eca@syzkaller.appspotmail.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      3ee7e869
    • W
      rseq: Avoid infinite recursion when delivering SIGSEGV · 784e0300
      由 Will Deacon 提交于 
      When delivering a signal to a task that is using rseq, we call into
__rseq_handle_notify_resume() so that the registers pushed in the
sigframe are updated to reflect the state of the restartable sequence
(for example, ensuring that the signal returns to the abort handler if
necessary).

However, if the rseq management fails due to an unrecoverable fault when
accessing userspace or certain combinations of RSEQ_CS_* flags, then we
will attempt to deliver a SIGSEGV. This has the potential for infinite
recursion if the rseq code continuously fails on signal delivery.

Avoid this problem by using force_sigsegv() instead of force_sig(), which
is explicitly designed to reset the SEGV handler to SIG_DFL in the case
of a recursive fault. In doing so, remove rseq_signal_deliver() from the
internal rseq API and have an optional struct ksignal * parameter to
rseq_handle_notify_resume() instead.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: peterz@infradead.org
Cc: paulmck@linux.vnet.ibm.com
Cc: boqun.feng@gmail.com
Link: https://lkml.kernel.org/r/1529664307-983-1-git-send-email-will.deacon@arm.com
      784e0300
  25. 22 6月, 2018 5 次提交