Commit Graph

874 Commits

Author SHA1 Message Date
Linus Torvalds a50243b1dd 5.1 Merge Window Pull Request
This has been a slightly more active cycle than normal with ongoing core
 changes and quite a lot of collected driver updates.
 
 - Various driver fixes for bnxt_re, cxgb4, hns, mlx5, pvrdma, rxe
 
 - A new data transfer mode for HFI1 giving higher performance
 
 - Significant functional and bug fix update to the mlx5 On-Demand-Paging MR
   feature
 
 - A chip hang reset recovery system for hns
 
 - Change mm->pinned_vm to an atomic64
 
 - Update bnxt_re to support a new 57500 chip
 
 - A sane netlink 'rdma link add' method for creating rxe devices and fixing
   the various unregistration race conditions in rxe's unregister flow
 
 - Allow lookup up objects by an ID over netlink
 
 - Various reworking of the core to driver interface:
   * Drivers should not assume umem SGLs are in PAGE_SIZE chunks
   * ucontext is accessed via udata not other means
   * Start to make the core code responsible for object memory
     allocation
   * Drivers should convert struct device to struct ib_device
     via a helper
   * Drivers have more tools to avoid use after unregister problems
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

Pull rdma updates from Jason Gunthorpe:
 "This has been a slightly more active cycle than normal with ongoing
  core changes and quite a lot of collected driver updates.

   - Various driver fixes for bnxt_re, cxgb4, hns, mlx5, pvrdma, rxe

   - A new data transfer mode for HFI1 giving higher performance

   - Significant functional and bug fix update to the mlx5
     On-Demand-Paging MR feature

   - A chip hang reset recovery system for hns

   - Change mm->pinned_vm to an atomic64

   - Update bnxt_re to support a new 57500 chip

   - A sane netlink 'rdma link add' method for creating rxe devices and
     fixing the various unregistration race conditions in rxe's
     unregister flow

   - Allow lookup up objects by an ID over netlink

   - Various reworking of the core to driver interface:
       - drivers should not assume umem SGLs are in PAGE_SIZE chunks
       - ucontext is accessed via udata not other means
       - start to make the core code responsible for object memory
         allocation
       - drivers should convert struct device to struct ib_device via a
         helper
       - drivers have more tools to avoid use after unregister problems"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (280 commits)
  net/mlx5: ODP support for XRC transport is not enabled by default in FW
  IB/hfi1: Close race condition on user context disable and close
  RDMA/umem: Revert broken 'off by one' fix
  RDMA/umem: minor bug fix in error handling path
  RDMA/hns: Use GFP_ATOMIC in hns_roce_v2_modify_qp
  cxgb4: kfree mhp after the debug print
  IB/rdmavt: Fix concurrency panics in QP post_send and modify to error
  IB/rdmavt: Fix loopback send with invalidate ordering
  IB/iser: Fix dma_nents type definition
  IB/mlx5: Set correct write permissions for implicit ODP MR
  bnxt_re: Clean cq for kernel consumers only
  RDMA/uverbs: Don't do double free of allocated PD
  RDMA: Handle ucontext allocations by IB/core
  RDMA/core: Fix a WARN() message
  bnxt_re: fix the regression due to changes in alloc_pbl
  IB/mlx4: Increase the timeout for CM cache
  IB/core: Abort page fault handler silently during owning process exit
  IB/mlx5: Validate correct PD before prefetch MR
  IB/mlx5: Protect against prefetch of invalid MR
  RDMA/uverbs: Store PR pointer before it is overwritten
  ...
2019-03-09 15:53:03 -08:00
YueHaibing fd2081ffce kernel/fork.c: remove duplicated include
Remove duplicated include.

Link: http://lkml.kernel.org/r/20181209062952.17736-1-yuehaibing@huawei.com
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-07 18:32:03 -08:00
Davidlohr Bueso 70f8a3ca68 mm: make mm->pinned_vm an atomic64 counter
Taking a sleeping lock to _only_ increment a variable is quite the
overkill, and pretty much all users do this. Furthermore, some drivers
(ie: infiniband and scif) that need pinned semantics can go to quite
some trouble to actually delay via workqueue (un)accounting for pinned
pages when not possible to acquire it.

By making the counter atomic we no longer need to hold the mmap_sem and
can simply some code around it for pinned_vm users. The counter is 64-bit
such that we need not worry about overflows such as rdma user input
controlled from userspace.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
2019-02-07 12:54:02 -07:00
Elena Reshetova f0b89d3958 sched/core: Convert task_struct.stack_refcount to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:

 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable task_struct.stack_refcount is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

** Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.

The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.

Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.

Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the task_struct.stack_refcount it might make a difference
in following places:

 - try_get_task_stack(): increment in refcount_inc_not_zero() only
   guarantees control dependency on success vs. fully ordered
   atomic counterpart
 - put_task_stack(): decrement in refcount_dec_and_test() only
   provides RELEASE ordering and control dependency on success
   vs. fully ordered atomic counterpart

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1547814450-18902-6-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:53:56 +01:00
Elena Reshetova ec1d281923 sched/core: Convert task_struct.usage to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:

 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable task_struct.usage is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

** Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.

The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.

Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.

Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the task_struct.usage it might make a difference
in following places:

 - put_task_struct(): decrement in refcount_dec_and_test() only
   provides RELEASE ordering and control dependency on success
   vs. fully ordered atomic counterpart

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1547814450-18902-5-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:53:55 +01:00
Elena Reshetova 60d4de3ff7 sched/core: Convert signal_struct.sigcnt to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:

 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable signal_struct.sigcnt is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

** Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.

The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.

Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.

Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the signal_struct.sigcnt it might make a difference
in following places:

 - put_signal_struct(): decrement in refcount_dec_and_test() only
   provides RELEASE ordering and control dependency on success
   vs. fully ordered atomic counterpart

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1547814450-18902-3-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:53:53 +01:00
Elena Reshetova d036bda7d0 sched/core: Convert sighand_struct.count to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:

 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable sighand_struct.count is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

** Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.

The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.

Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.

Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the sighand_struct.count it might make a difference
in following places:

 - __cleanup_sighand: decrement in refcount_dec_and_test() only
   provides RELEASE ordering and control dependency on success
   vs. fully ordered atomic counterpart

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1547814450-18902-2-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:53:52 +01:00
Linus Torvalds a88cc8da02 Merge branch 'akpm' (patches from Andrew)
Merge misc fixes from Andrew Morton:
 "14 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm, page_alloc: do not wake kswapd with zone lock held
  hugetlbfs: revert "use i_mmap_rwsem for more pmd sharing synchronization"
  hugetlbfs: revert "Use i_mmap_rwsem to fix page fault/truncate race"
  mm: page_mapped: don't assume compound page is huge or THP
  mm/memory.c: initialise mmu_notifier_range correctly
  tools/vm/page_owner: use page_owner_sort in the use example
  kasan: fix krealloc handling for tag-based mode
  kasan: make tag based mode work with CONFIG_HARDENED_USERCOPY
  kasan, arm64: use ARCH_SLAB_MINALIGN instead of manual aligning
  mm, memcg: fix reclaim deadlock with writeback
  mm/usercopy.c: no check page span for stack objects
  slab: alien caches must not be initialized if the allocation of the alien cache failed
  fork, memcg: fix cached_stacks case
  zram: idle writeback fixes and cleanup
2019-01-08 18:58:29 -08:00
Shakeel Butt ba4a45746c fork, memcg: fix cached_stacks case
Commit 5eed6f1dff ("fork,memcg: fix crash in free_thread_stack on
memcg charge fail") fixes a crash caused due to failed memcg charge of
the kernel stack.  However the fix misses the cached_stacks case which
this patch fixes.  So, the same crash can happen if the memcg charge of
a cached stack is failed.

Link: http://lkml.kernel.org/r/20190102180145.57406-1-shakeelb@google.com
Fixes: 5eed6f1dff ("fork,memcg: fix crash in free_thread_stack on memcg charge fail")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-08 17:15:11 -08:00
David Herrmann 7b55851367 fork: record start_time late
This changes the fork(2) syscall to record the process start_time after
initializing the basic task structure but still before making the new
process visible to user-space.

Technically, we could record the start_time anytime during fork(2).  But
this might lead to scenarios where a start_time is recorded long before
a process becomes visible to user-space.  For instance, with
userfaultfd(2) and TLS, user-space can delay the execution of fork(2)
for an indefinite amount of time (and will, if this causes network
access, or similar).

By recording the start_time late, it much closer reflects the point in
time where the process becomes live and can be observed by other
processes.

Lastly, this makes it much harder for user-space to predict and control
the start_time they get assigned.  Previously, user-space could fork a
process and stall it in copy_thread_tls() before its pid is allocated,
but after its start_time is recorded.  This can be misused to later-on
cycle through PIDs and resume the stalled fork(2) yielding a process
that has the same pid and start_time as a process that existed before.
This can be used to circumvent security systems that identify processes
by their pid+start_time combination.

Even though user-space was always aware that start_time recording is
flaky (but several projects are known to still rely on start_time-based
identification), changing the start_time to be recorded late will help
mitigate existing attacks and make it much harder for user-space to
control the start_time a process gets assigned.

Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-08 09:40:53 -08:00
Yi Wang fb5bf31722 fork: fix some -Wmissing-prototypes warnings
We get a warning when building kernel with W=1:

  kernel/fork.c:167:13: warning: no previous prototype for `arch_release_thread_stack' [-Wmissing-prototypes]
  kernel/fork.c:779:13: warning: no previous prototype for `fork_init' [-Wmissing-prototypes]

Add the missing declaration in head file to fix this.

Also, remove arch_release_thread_stack() completely because no arch
seems to implement it since bb9d81264 (arch: remove tile port).

Link: http://lkml.kernel.org/r/1542170087-23645-1-git-send-email-wang.yi59@zte.com.cn
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-04 13:13:47 -08:00
YueHaibing 0f4991e8fd kernel/fork.c: mark 'stack_vm_area' with __maybe_unused
Fixes gcc '-Wunused-but-set-variable' warning when CONFIG_VMAP_STACK is
not set:

kernel/fork.c: In function 'dup_task_struct':
kernel/fork.c:843:20: warning:
 variable 'stack_vm_area' set but not used [-Wunused-but-set-variable]

Link: http://lkml.kernel.org/r/1545965190-2381-1-git-send-email-yuehaibing@huawei.com
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:52 -08:00
Arun KS ca79b0c211 mm: convert totalram_pages and totalhigh_pages variables to atomic
totalram_pages and totalhigh_pages are made static inline function.

Main motivation was that managed_page_count_lock handling was complicating
things.  It was discussed in length here,
https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes
better to remove the lock and convert variables to atomic, with preventing
poteintial store-to-read tearing as a bonus.

[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
Suggested-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:47 -08:00
Arun KS 3d6357de8a mm: reference totalram_pages and managed_pages once per function
Patch series "mm: convert totalram_pages, totalhigh_pages and managed
pages to atomic", v5.

This series converts totalram_pages, totalhigh_pages and
zone->managed_pages to atomic variables.

totalram_pages, zone->managed_pages and totalhigh_pages updates are
protected by managed_page_count_lock, but readers never care about it.
Convert these variables to atomic to avoid readers potentially seeing a
store tear.

Main motivation was that managed_page_count_lock handling was complicating
things.  It was discussed in length here,
https://lore.kernel.org/patchwork/patch/995739/#1181785 It seemes better
to remove the lock and convert variables to atomic.  With the change,
preventing poteintial store-to-read tearing comes as a bonus.

This patch (of 4):

This is in preparation to a later patch which converts totalram_pages and
zone->managed_pages to atomic variables.  Please note that re-reading the
value might lead to a different value and as such it could lead to
unexpected behavior.  There are no known bugs as a result of the current
code but it is better to prevent from them in principle.

Link: http://lkml.kernel.org/r/1542090790-21750-2-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:47 -08:00
Rik van Riel 5eed6f1dff fork,memcg: fix crash in free_thread_stack on memcg charge fail
Commit 9b6f7e163c ("mm: rework memcg kernel stack accounting") will
result in fork failing if allocating a kernel stack for a task in
dup_task_struct exceeds the kernel memory allowance for that cgroup.

Unfortunately, it also results in a crash.

This is due to the code jumping to free_stack and calling
free_thread_stack when the memcg kernel stack charge fails, but without
tsk->stack pointing at the freshly allocated stack.

This in turn results in the vfree_atomic in free_thread_stack oopsing
with a backtrace like this:

#5 [ffffc900244efc88] die at ffffffff8101f0ab
 #6 [ffffc900244efcb8] do_general_protection at ffffffff8101cb86
 #7 [ffffc900244efce0] general_protection at ffffffff818ff082
    [exception RIP: llist_add_batch+7]
    RIP: ffffffff8150d487  RSP: ffffc900244efd98  RFLAGS: 00010282
    RAX: 0000000000000000  RBX: ffff88085ef55980  RCX: 0000000000000000
    RDX: ffff88085ef55980  RSI: 343834343531203a  RDI: 343834343531203a
    RBP: ffffc900244efd98   R8: 0000000000000001   R9: ffff8808578c3600
    R10: 0000000000000000  R11: 0000000000000001  R12: ffff88029f6c21c0
    R13: 0000000000000286  R14: ffff880147759b00  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #8 [ffffc900244efda0] vfree_atomic at ffffffff811df2c7
 #9 [ffffc900244efdb8] copy_process at ffffffff81086e37
#10 [ffffc900244efe98] _do_fork at ffffffff810884e0
#11 [ffffc900244eff10] sys_vfork at ffffffff810887ff
#12 [ffffc900244eff20] do_syscall_64 at ffffffff81002a43
    RIP: 000000000049b948  RSP: 00007ffcdb307830  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 0000000000896030  RCX: 000000000049b948
    RDX: 0000000000000000  RSI: 00007ffcdb307790  RDI: 00000000005d7421
    RBP: 000000000067370f   R8: 00007ffcdb3077b0   R9: 000000000001ed00
    R10: 0000000000000008  R11: 0000000000000246  R12: 0000000000000040
    R13: 000000000000000f  R14: 0000000000000000  R15: 000000000088d018
    ORIG_RAX: 000000000000003a  CS: 0033  SS: 002b

The simplest fix is to assign tsk->stack right where it is allocated.

Link: http://lkml.kernel.org/r/20181214231726.7ee4843c@imladris.surriel.com
Fixes: 9b6f7e163c ("mm: rework memcg kernel stack accounting")
Signed-off-by: Rik van Riel <riel@surriel.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-21 14:51:18 -08:00
Linus Torvalds 2d6bb6adb7 New gcc plugin: stackleak
- Introduces the stackleak gcc plugin ported from grsecurity by Alexander
   Popov, with x86 and arm64 support.
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Merge tag 'stackleak-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull stackleak gcc plugin from Kees Cook:
 "Please pull this new GCC plugin, stackleak, for v4.20-rc1. This plugin
  was ported from grsecurity by Alexander Popov. It provides efficient
  stack content poisoning at syscall exit. This creates a defense
  against at least two classes of flaws:

   - Uninitialized stack usage. (We continue to work on improving the
     compiler to do this in other ways: e.g. unconditional zero init was
     proposed to GCC and Clang, and more plugin work has started too).

   - Stack content exposure. By greatly reducing the lifetime of valid
     stack contents, exposures via either direct read bugs or unknown
     cache side-channels become much more difficult to exploit. This
     complements the existing buddy and heap poisoning options, but
     provides the coverage for stacks.

  The x86 hooks are included in this series (which have been reviewed by
  Ingo, Dave Hansen, and Thomas Gleixner). The arm64 hooks have already
  been merged through the arm64 tree (written by Laura Abbott and
  reviewed by Mark Rutland and Will Deacon).

  With VLAs having been removed this release, there is no need for
  alloca() protection, so it has been removed from the plugin"

* tag 'stackleak-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  arm64: Drop unneeded stackleak_check_alloca()
  stackleak: Allow runtime disabling of kernel stack erasing
  doc: self-protection: Add information about STACKLEAK feature
  fs/proc: Show STACKLEAK metrics in the /proc file system
  lkdtm: Add a test for STACKLEAK
  gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack
  x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
2018-11-01 11:46:27 -07:00
Johannes Weiner eb414681d5 psi: pressure stall information for CPU, memory, and IO
When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills.  In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.

In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.

A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively.  Stall states are aggregate versions of the per-task delay
accounting delays:

       cpu: some tasks are runnable but not executing on a CPU
       memory: tasks are reclaiming, or waiting for swapin or thrashing cache
       io: tasks are waiting for io completions

These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit.  They can also indicate when the system
is approaching lockup scenarios and OOMs.

To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states.  Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime.  A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).

[hannes@cmpxchg.org: doc fixlet, per Randy]
  Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
  Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
  Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
  Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 16:26:32 -07:00
Roman Gushchin 9b6f7e163c mm: rework memcg kernel stack accounting
If CONFIG_VMAP_STACK is set, kernel stacks are allocated using
__vmalloc_node_range() with __GFP_ACCOUNT.  So kernel stack pages are
charged against corresponding memory cgroups on allocation and uncharged
on releasing them.

The problem is that we do cache kernel stacks in small per-cpu caches and
do reuse them for new tasks, which can belong to different memory cgroups.

Each stack page still holds a reference to the original cgroup, so the
cgroup can't be released until the vmap area is released.

To make this happen we need more than two subsequent exits without forks
in between on the current cpu, which makes it very unlikely to happen.  As
a result, I saw a significant number of dying cgroups (in theory, up to 2
* number_of_cpu + number_of_tasks), which can't be released even by
significant memory pressure.

As a cgroup structure can take a significant amount of memory (first of
all, per-cpu data like memcg statistics), it leads to a noticeable waste
of memory.

Link: http://lkml.kernel.org/r/20180827162621.30187-1-guro@fb.com
Fixes: ac496bf48d ("fork: Optimize task creation by caching two thread stacks per CPU if CONFIG_VMAP_STACK=y")
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 16:25:19 -07:00
Nadav Amit 1ed0cc5a01 mm: respect arch_dup_mmap() return value
Commit d70f2a14b7 ("include/linux/sched/mm.h: uninline mmdrop_async(),
etc") ignored the return value of arch_dup_mmap(). As a result, on x86,
a failure to duplicate the LDT (e.g. due to memory allocation error)
would leave the duplicated memory mapping in an inconsistent state.

Fix by using the return value, as it was before the change.

Link: http://lkml.kernel.org/r/20180823051229.211856-1-namit@vmware.com
Fixes: d70f2a14b7 ("include/linux/sched/mm.h: uninline mmdrop_async(), etc")
Signed-off-by: Nadav Amit <namit@vmware.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-09-04 16:45:02 -07:00
Alexander Popov afaef01c00 x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
The STACKLEAK feature (initially developed by PaX Team) has the following
benefits:

1. Reduces the information that can be revealed through kernel stack leak
   bugs. The idea of erasing the thread stack at the end of syscalls is
   similar to CONFIG_PAGE_POISONING and memzero_explicit() in kernel
   crypto, which all comply with FDP_RIP.2 (Full Residual Information
   Protection) of the Common Criteria standard.

2. Blocks some uninitialized stack variable attacks (e.g. CVE-2017-17712,
   CVE-2010-2963). That kind of bugs should be killed by improving C
   compilers in future, which might take a long time.

This commit introduces the code filling the used part of the kernel
stack with a poison value before returning to userspace. Full
STACKLEAK feature also contains the gcc plugin which comes in a
separate commit.

The STACKLEAK feature is ported from grsecurity/PaX. More information at:
  https://grsecurity.net/
  https://pax.grsecurity.net/

This code is modified from Brad Spengler/PaX Team's code in the last
public patch of grsecurity/PaX based on our understanding of the code.
Changes or omissions from the original code are ours and don't reflect
the original grsecurity/PaX code.

Performance impact:

Hardware: Intel Core i7-4770, 16 GB RAM

Test #1: building the Linux kernel on a single core
        0.91% slowdown

Test #2: hackbench -s 4096 -l 2000 -g 15 -f 25 -P
        4.2% slowdown

So the STACKLEAK description in Kconfig includes: "The tradeoff is the
performance impact: on a single CPU system kernel compilation sees a 1%
slowdown, other systems and workloads may vary and you are advised to
test this feature on your expected workload before deploying it".

Signed-off-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-09-04 10:35:47 -07:00
Linus Torvalds cd9b44f907 Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:

 - the rest of MM

 - procfs updates

 - various misc things

 - more y2038 fixes

 - get_maintainer updates

 - lib/ updates

 - checkpatch updates

 - various epoll updates

 - autofs updates

 - hfsplus

 - some reiserfs work

 - fatfs updates

 - signal.c cleanups

 - ipc/ updates

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (166 commits)
  ipc/util.c: update return value of ipc_getref from int to bool
  ipc/util.c: further variable name cleanups
  ipc: simplify ipc initialization
  ipc: get rid of ids->tables_initialized hack
  lib/rhashtable: guarantee initial hashtable allocation
  lib/rhashtable: simplify bucket_table_alloc()
  ipc: drop ipc_lock()
  ipc/util.c: correct comment in ipc_obtain_object_check
  ipc: rename ipcctl_pre_down_nolock()
  ipc/util.c: use ipc_rcu_putref() for failues in ipc_addid()
  ipc: reorganize initialization of kern_ipc_perm.seq
  ipc: compute kern_ipc_perm.id under the ipc lock
  init/Kconfig: remove EXPERT from CHECKPOINT_RESTORE
  fs/sysv/inode.c: use ktime_get_real_seconds() for superblock stamp
  adfs: use timespec64 for time conversion
  kernel/sysctl.c: fix typos in comments
  drivers/rapidio/devices/rio_mport_cdev.c: remove redundant pointer md
  fork: don't copy inconsistent signal handler state to child
  signal: make get_signal() return bool
  signal: make sigkill_pending() return bool
  ...
2018-08-22 12:34:08 -07:00
Jann Horn 06e62a46bb fork: don't copy inconsistent signal handler state to child
Before this change, if a multithreaded process forks while one of its
threads is changing a signal handler using sigaction(), the memcpy() in
copy_sighand() can race with the struct assignment in do_sigaction().  It
isn't clear whether this can cause corruption of the userspace signal
handler pointer, but it definitely can cause inconsistency between
different fields of struct sigaction.

Take the appropriate spinlock to avoid this.

I have tested that this patch prevents inconsistency between sa_sigaction
and sa_flags, which is possible before this patch.

Link: http://lkml.kernel.org/r/20180702145108.73189-1-jannh@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:51 -07:00
Dmitry Vyukov a2e5144538 kernel/hung_task.c: allow to set checking interval separately from timeout
Currently task hung checking interval is equal to timeout, as the result
hung is detected anywhere between timeout and 2*timeout.  This is fine for
most interactive environments, but this hurts automated testing setups
(syzbot).  In an automated setup we need to strictly order CPU lockup <
RCU stall < workqueue lockup < task hung < silent loss, so that RCU stall
is not detected as task hung and task hung is not detected as silent
machine loss.  The large variance in task hung detection timeout requires
setting silent machine loss timeout to a very large value (e.g.  if task
hung is 3 mins, then silent loss need to be set to ~7 mins).  The
additional 3 minutes significantly reduce testing efficiency because
usually we crash kernel within a minute, and this can add hours to bug
localization process as it needs to do dozens of tests.

Allow setting checking interval separately from timeout.  This allows to
set timeout to, say, 3 minutes, but checking interval to 10 secs.

The interval is controlled via a new hung_task_check_interval_secs sysctl,
similar to the existing hung_task_timeout_secs sysctl.  The default value
of 0 results in the current behavior: checking interval is equal to
timeout.

[akpm@linux-foundation.org: update hung_task_timeout_max's comment]
Link: http://lkml.kernel.org/r/20180611111004.203513-1-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:47 -07:00
Andrew Morton a670468f5e mm: zero out the vma in vma_init()
Rather than in vm_area_alloc().  To ensure that the various oddball
stack-based vmas are in a good state.  Some of the callers were zeroing
them out, others were not.

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:44 -07:00
Linus Torvalds 0214f46b3a Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull core signal handling updates from Eric Biederman:
 "It was observed that a periodic timer in combination with a
  sufficiently expensive fork could prevent fork from every completing.
  This contains the changes to remove the need for that restart.

  This set of changes is split into several parts:

   - The first part makes PIDTYPE_TGID a proper pid type instead
     something only for very special cases. The part starts using
     PIDTYPE_TGID enough so that in __send_signal where signals are
     actually delivered we know if the signal is being sent to a a group
     of processes or just a single process.

   - With that prep work out of the way the logic in fork is modified so
     that fork logically makes signals received while it is running
     appear to be received after the fork completes"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (22 commits)
  signal: Don't send signals to tasks that don't exist
  signal: Don't restart fork when signals come in.
  fork: Have new threads join on-going signal group stops
  fork: Skip setting TIF_SIGPENDING in ptrace_init_task
  signal: Add calculate_sigpending()
  fork: Unconditionally exit if a fatal signal is pending
  fork: Move and describe why the code examines PIDNS_ADDING
  signal: Push pid type down into complete_signal.
  signal: Push pid type down into __send_signal
  signal: Push pid type down into send_signal
  signal: Pass pid type into do_send_sig_info
  signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task
  signal: Pass pid type into group_send_sig_info
  signal: Pass pid and pid type into send_sigqueue
  posix-timers: Noralize good_sigevent
  signal: Use PIDTYPE_TGID to clearly store where file signals will be sent
  pid: Implement PIDTYPE_TGID
  pids: Move the pgrp and session pid pointers from task_struct to signal_struct
  kvm: Don't open code task_pid in kvm_vcpu_ioctl
  pids: Compute task_tgid using signal->leader_pid
  ...
2018-08-21 13:47:29 -07:00
Shakeel Butt d46eb14b73 fs: fsnotify: account fsnotify metadata to kmemcg
Patch series "Directed kmem charging", v8.

The Linux kernel's memory cgroup allows limiting the memory usage of the
jobs running on the system to provide isolation between the jobs.  All
the kernel memory allocated in the context of the job and marked with
__GFP_ACCOUNT will also be included in the memory usage and be limited
by the job's limit.

The kernel memory can only be charged to the memcg of the process in
whose context kernel memory was allocated.  However there are cases
where the allocated kernel memory should be charged to the memcg
different from the current processes's memcg.  This patch series
contains two such concrete use-cases i.e.  fsnotify and buffer_head.

The fsnotify event objects can consume a lot of system memory for large
or unlimited queues if there is either no or slow listener.  The events
are allocated in the context of the event producer.  However they should
be charged to the event consumer.  Similarly the buffer_head objects can
be allocated in a memcg different from the memcg of the page for which
buffer_head objects are being allocated.

To solve this issue, this patch series introduces mechanism to charge
kernel memory to a given memcg.  In case of fsnotify events, the memcg
of the consumer can be used for charging and for buffer_head, the memcg
of the page can be charged.  For directed charging, the caller can use
the scope API memalloc_[un]use_memcg() to specify the memcg to charge
for all the __GFP_ACCOUNT allocations within the scope.

This patch (of 2):

A lot of memory can be consumed by the events generated for the huge or
unlimited queues if there is either no or slow listener.  This can cause
system level memory pressure or OOMs.  So, it's better to account the
fsnotify kmem caches to the memcg of the listener.

However the listener can be in a different memcg than the memcg of the
producer and these allocations happen in the context of the event
producer.  This patch introduces remote memcg charging API which the
producer can use to charge the allocations to the memcg of the listener.

There are seven fsnotify kmem caches and among them allocations from
dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and
inotify_inode_mark_cachep happens in the context of syscall from the
listener.  So, SLAB_ACCOUNT is enough for these caches.

The objects from fsnotify_mark_connector_cachep are not accounted as
they are small compared to the notification mark or events and it is
unclear whom to account connector to since it is shared by all events
attached to the inode.

The allocations from the event caches happen in the context of the event
producer.  For such caches we will need to remote charge the allocations
to the listener's memcg.  Thus we save the memcg reference in the
fsnotify_group structure of the listener.

This patch has also moved the members of fsnotify_group to keep the size
same, at least for 64 bit build, even with additional member by filling
the holes.

[shakeelb@google.com: use GFP_KERNEL_ACCOUNT rather than open-coding it]
  Link: http://lkml.kernel.org/r/20180702215439.211597-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-17 16:20:30 -07:00
Linus Torvalds 73ba2fb33c for-4.19/block-20180812
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Merge tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block

Pull block updates from Jens Axboe:
 "First pull request for this merge window, there will also be a
  followup request with some stragglers.

  This pull request contains:

   - Fix for a thundering heard issue in the wbt block code (Anchal
     Agarwal)

   - A few NVMe pull requests:
      * Improved tracepoints (Keith)
      * Larger inline data support for RDMA (Steve Wise)
      * RDMA setup/teardown fixes (Sagi)
      * Effects log suppor for NVMe target (Chaitanya Kulkarni)
      * Buffered IO suppor for NVMe target (Chaitanya Kulkarni)
      * TP4004 (ANA) support (Christoph)
      * Various NVMe fixes

   - Block io-latency controller support. Much needed support for
     properly containing block devices. (Josef)

   - Series improving how we handle sense information on the stack
     (Kees)

   - Lightnvm fixes and updates/improvements (Mathias/Javier et al)

   - Zoned device support for null_blk (Matias)

   - AIX partition fixes (Mauricio Faria de Oliveira)

   - DIF checksum code made generic (Max Gurtovoy)

   - Add support for discard in iostats (Michael Callahan / Tejun)

   - Set of updates for BFQ (Paolo)

   - Removal of async write support for bsg (Christoph)

   - Bio page dirtying and clone fixups (Christoph)

   - Set of bcache fix/changes (via Coly)

   - Series improving blk-mq queue setup/teardown speed (Ming)

   - Series improving merging performance on blk-mq (Ming)

   - Lots of other fixes and cleanups from a slew of folks"

* tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block: (190 commits)
  blkcg: Make blkg_root_lookup() work for queues in bypass mode
  bcache: fix error setting writeback_rate through sysfs interface
  null_blk: add lock drop/acquire annotation
  Blk-throttle: reduce tail io latency when iops limit is enforced
  block: paride: pd: mark expected switch fall-throughs
  block: Ensure that a request queue is dissociated from the cgroup controller
  block: Introduce blk_exit_queue()
  blkcg: Introduce blkg_root_lookup()
  block: Remove two superfluous #include directives
  blk-mq: count the hctx as active before allocating tag
  block: bvec_nr_vecs() returns value for wrong slab
  bcache: trivial - remove tailing backslash in macro BTREE_FLAG
  bcache: make the pr_err statement used for ENOENT only in sysfs_attatch section
  bcache: set max writeback rate when I/O request is idle
  bcache: add code comments for bset.c
  bcache: fix mistaken comments in request.c
  bcache: fix mistaken code comments in bcache.h
  bcache: add a comment in super.c
  bcache: avoid unncessary cache prefetch bch_btree_node_get()
  bcache: display rate debug parameters to 0 when writeback is not running
  ...
2018-08-14 10:23:25 -07:00
Linus Torvalds 203b4fc903 Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Thomas Gleixner:

 - Make lazy TLB mode even lazier to avoid pointless switch_mm()
   operations, which reduces CPU load by 1-2% for memcache workloads

 - Small cleanups and improvements all over the place

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Remove redundant check for kmem_cache_create()
  arm/asm/tlb.h: Fix build error implicit func declaration
  x86/mm/tlb: Make clear_asid_other() static
  x86/mm/tlb: Skip atomic operations for 'init_mm' in switch_mm_irqs_off()
  x86/mm/tlb: Always use lazy TLB mode
  x86/mm/tlb: Only send page table free TLB flush to lazy TLB CPUs
  x86/mm/tlb: Make lazy TLB mode lazier
  x86/mm/tlb: Restructure switch_mm_irqs_off()
  x86/mm/tlb: Leave lazy TLB mode at page table free time
  mm: Allocate the mm_cpumask (mm->cpu_bitmap[]) dynamically based on nr_cpu_ids
  x86/mm: Add TLB purge to free pmd/pte page interfaces
  ioremap: Update pgtable free interfaces with addr
  x86/mm: Disable ioremap free page handling on x86-PAE
2018-08-13 16:29:35 -07:00
Eric W. Biederman c3ad2c3b02 signal: Don't restart fork when signals come in.
Wen Yang <wen.yang99@zte.com.cn> and majiang <ma.jiang@zte.com.cn>
report that a periodic signal received during fork can cause fork to
continually restart preventing an application from making progress.

The code was being overly pessimistic.  Fork needs to guarantee that a
signal sent to multiple processes is logically delivered before the
fork and just to the forking process or logically delivered after the
fork to both the forking process and it's newly spawned child.  For
signals like periodic timers that are always delivered to a single
process fork can safely complete and let them appear to logically
delivered after the fork().

While examining this issue I also discovered that fork today will miss
signals delivered to multiple processes during the fork and handled by
another thread.  Similarly the current code will also miss blocked
signals that are delivered to multiple process, as those signals will
not appear pending during fork.

Add a list of each thread that is currently forking, and keep on that
list a signal set that records all of the signals sent to multiple
processes.  When fork completes initialize the new processes
shared_pending signal set with it.  The calculate_sigpending function
will see those signals and set TIF_SIGPENDING causing the new task to
take the slow path to userspace to handle those signals.  Making it
appear as if those signals were received immediately after the fork.

It is not possible to send real time signals to multiple processes and
exceptions don't go to multiple processes, which means that that are
no signals sent to multiple processes that require siginfo.  This
means it is safe to not bother collecting siginfo on signals sent
during fork.

The sigaction of a child of fork is initially the same as the
sigaction of the parent process.  So a signal the parent ignores the
child will also initially ignore.  Therefore it is safe to ignore
signals sent to multiple processes and ignored by the forking process.

Signals sent to only a single process or only a single thread and delivered
during fork are treated as if they are received after the fork, and generally
not dealt with.  They won't cause any problems.

V2: Added removal from the multiprocess list on failure.
V3: Use -ERESTARTNOINTR directly
V4: - Don't queue both SIGCONT and SIGSTOP
    - Initialize signal_struct.multiprocess in init_task
    - Move setting of shared_pending to before the new task
      is visible to signals.  This prevents signals from comming
      in before shared_pending.signal is set to delayed.signal
      and being lost.
V5: - rework list add and delete to account for idle threads
v6: - Use sigdelsetmask when removing stop signals

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200447
Reported-by: Wen Yang <wen.yang99@zte.com.cn> and
Reported-by: majiang <ma.jiang@zte.com.cn>
Fixes: 4a2c7a7837 ("[PATCH] make fork() atomic wrt pgrp/session signals")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-08-09 13:07:01 -05:00
Jens Axboe 05b9ba4b55 Linux 4.18-rc6
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Merge tag 'v4.18-rc6' into for-4.19/block2

Pull in 4.18-rc6 to get the NVMe core AEN change to avoid a
merge conflict down the line.

Signed-of-by: Jens Axboe <axboe@kernel.dk>
2018-08-05 19:32:09 -06:00
Eric W. Biederman 924de3b8c9 fork: Have new threads join on-going signal group stops
There are only two signals that are delivered to every member of a
signal group: SIGSTOP and SIGKILL.  Signal delivery requires every
signal appear to be delivered either before or after a clone syscall.
SIGKILL terminates the clone so does not need to be considered.  Which
leaves only SIGSTOP that needs to be considered when creating new
threads.

Today in the event of a group stop TIF_SIGPENDING will get set and the
fork will restart ensuring the fork syscall participates in the group
stop.

A fork (especially of a process with a lot of memory) is one of the
most expensive system so we really only want to restart a fork when
necessary.

It is easy so check to see if a SIGSTOP is ongoing and have the new
thread join it immediate after the clone completes.  Making it appear
the clone completed happened just before the SIGSTOP.

The calculate_sigpending function will see the bits set in jobctl and
set TIF_SIGPENDING to ensure the new task takes the slow path to userspace.

V2: The call to task_join_group_stop was moved before the new task is
    added to the thread group list.  This should not matter as
    sighand->siglock is held over both the addition of the threads,
    the call to task_join_group_stop and do_signal_stop.  But the change
    is trivial and it is one less thing to worry about when reading
    the code.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-08-03 20:20:14 -05:00
Josef Bacik 2c323017e3 blk-cgroup: clear the throttle queue on fork
We were hitting a panic in production where we put too many times on the
request queue.  This is because we'd get the throttle_queue of the
parent if we fork()'ed while we needed to be throttled, but we didn't
have a reference on it.  Instead just clear these flags on fork so the
child doesn't pay for the sins of its father.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-01 09:16:04 -06:00
Kirill A. Shutemov 027232da7c mm: introduce vma_init()
Not all VMAs allocated with vm_area_alloc().  Some of them allocated on
stack or in data segment.

The new helper can be use to initialize VMA properly regardless where it
was allocated.

Link: http://lkml.kernel.org/r/20180724121139.62570-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-07-26 19:38:03 -07:00
Eric W. Biederman 7673bf553b fork: Unconditionally exit if a fatal signal is pending
In practice this does not change anything as testing for fatal_signal_pending
and exiting for with an error code duplicates the work of the next clause
which recalculates pending signals and then exits fork if any are pending.
In both cases the pending signal will trigger the slow path when existing
to userspace, and the fatal signal will cause do_exit to be called.

The advantage of making this a separate test is that it makes it clear
processing the fatal signal will terminate the fork, and it allows the
rest of the signal logic to be updated without fear that this important
case will be lost.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-23 08:01:10 -05:00
Eric W. Biederman 4ca1d3ee46 fork: Move and describe why the code examines PIDNS_ADDING
Normally this would be something that would be handled by handling
signals that are sent to a group of processes but in this case the
forking process is not a member of the group being signaled.  Thus
special code is needed to prevent a race with pid namespaces exiting,
and fork adding new processes within them.

Move this test up before the signal restart just in case signals are
also pending.  Fatal conditions should take presedence over restarts.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-23 07:57:12 -05:00
Linus Torvalds 490fc05386 mm: make vm_area_alloc() initialize core fields
Like vm_area_dup(), it initializes the anon_vma_chain head, and the
basic mm pointer.

The rest of the fields end up being different for different users,
although the plan is to also initialize the 'vm_ops' field to a dummy
entry.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-07-21 15:24:03 -07:00
Linus Torvalds 95faf6992d mm: make vm_area_dup() actually copy the old vma data
.. and re-initialize th eanon_vma_chain head.

This removes some boiler-plate from the users, and also makes it clear
why it didn't need use the 'zalloc()' version.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-07-21 14:48:45 -07:00
Linus Torvalds 3928d4f5ee mm: use helper functions for allocating and freeing vm_area structs
The vm_area_struct is one of the most fundamental memory management
objects, but the management of it is entirely open-coded evertwhere,
ranging from allocation and freeing (using kmem_cache_[z]alloc and
kmem_cache_free) to initializing all the fields.

We want to unify this in order to end up having some unified
initialization of the vmas, and the first step to this is to at least
have basic allocation functions.

Right now those functions are literally just wrappers around the
kmem_cache_*() calls.  This is a purely mechanical conversion:

    # new vma:
    kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL) -> vm_area_alloc()

    # copy old vma
    kmem_cache_alloc(vm_area_cachep, GFP_KERNEL) -> vm_area_dup(old)

    # free vma
    kmem_cache_free(vm_area_cachep, vma) -> vm_area_free(vma)

to the point where the old vma passed in to the vm_area_dup() function
isn't even used yet (because I've left all the old manual initialization
alone).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-07-21 13:48:51 -07:00
Eric W. Biederman 6883f81aac pid: Implement PIDTYPE_TGID
Everywhere except in the pid array we distinguish between a tasks pid and
a tasks tgid (thread group id).  Even in the enumeration we want that
distinction sometimes so we have added __PIDTYPE_TGID.  With leader_pid
we almost have an implementation of PIDTYPE_TGID in struct signal_struct.

Add PIDTYPE_TGID as a first class member of the pid_type enumeration and
into the pids array.  Then remove the __PIDTYPE_TGID special case and the
leader_pid in signal_struct.

The net size increase is just an extra pointer added to struct pid and
an extra pair of pointers of an hlist_node added to task_struct.

The effect on code maintenance is the removal of a number of special
cases today and the potential to remove many more special cases as
PIDTYPE_TGID gets used to it's fullest.  The long term potential
is allowing zombie thread group leaders to exit, which will remove
a lot more special cases in the code.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21 10:43:12 -05:00
Eric W. Biederman 2c4704756c pids: Move the pgrp and session pid pointers from task_struct to signal_struct
To access these fields the code always has to go to group leader so
going to signal struct is no loss and is actually a fundamental simplification.

This saves a little bit of memory by only allocating the pid pointer array
once instead of once for every thread, and even better this removes a
few potential races caused by the fact that group_leader can be changed
by de_thread, while signal_struct can not.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21 10:43:12 -05:00
Rik van Riel c1a2f7f0c0 mm: Allocate the mm_cpumask (mm->cpu_bitmap[]) dynamically based on nr_cpu_ids
The mm_struct always contains a cpumask bitmap, regardless of
CONFIG_CPUMASK_OFFSTACK. That means the first step can be to
simplify things, and simply have one bitmask at the end of the
mm_struct for the mm_cpumask.

This does necessitate moving everything else in mm_struct into
an anonymous sub-structure, which can be randomized when struct
randomization is enabled.

The second step is to determine the correct size for the
mm_struct slab object from the size of the mm_struct
(excluding the CPU bitmap) and the size the cpumask.

For init_mm we can simply allocate the maximum size this
kernel is compiled for, since we only have one init_mm
in the system, anyway.

Pointer magic by Mike Galbraith, to evade -Wstringop-overflow
getting confused by the dynamically sized array.

Tested-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Rik van Riel <riel@surriel.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Cc: luto@kernel.org
Link: http://lkml.kernel.org/r/20180716190337.26133-2-riel@surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-17 09:35:30 +02:00
Tetsuo Handa 655c79bb40 mm: check for SIGKILL inside dup_mmap() loop
As a theoretical problem, dup_mmap() of an mm_struct with 60000+ vmas
can loop while potentially allocating memory, with mm->mmap_sem held for
write by current thread.  This is bad if current thread was selected as
an OOM victim, for current thread will continue allocations using memory
reserves while OOM reaper is unable to reclaim memory.

As an actually observable problem, it is not difficult to make OOM
reaper unable to reclaim memory if the OOM victim is blocked at
i_mmap_lock_write() in this loop.  Unfortunately, since nobody can
explain whether it is safe to use killable wait there, let's check for
SIGKILL before trying to allocate memory.  Even without an OOM event,
there is no point with continuing the loop from the beginning if current
thread is killed.

I tested with debug printk().  This patch should be safe because we
already fail if security_vm_enough_memory_mm() or
kmem_cache_alloc(GFP_KERNEL) fails and exit_mmap() handles it.

   ***** Aborting dup_mmap() due to SIGKILL *****
   ***** Aborting dup_mmap() due to SIGKILL *****
   ***** Aborting dup_mmap() due to SIGKILL *****
   ***** Aborting dup_mmap() due to SIGKILL *****
   ***** Aborting exit_mmap() due to NULL mmap *****

[akpm@linux-foundation.org: add comment]
Link: http://lkml.kernel.org/r/201804071938.CDE04681.SOFVQJFtMHOOLF@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-15 07:55:24 +09:00
Linus Torvalds 050e9baa9d Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables
The changes to automatically test for working stack protector compiler
support in the Kconfig files removed the special STACKPROTECTOR_AUTO
option that picked the strongest stack protector that the compiler
supported.

That was all a nice cleanup - it makes no sense to have the AUTO case
now that the Kconfig phase can just determine the compiler support
directly.

HOWEVER.

It also meant that doing "make oldconfig" would now _disable_ the strong
stackprotector if you had AUTO enabled, because in a legacy config file,
the sane stack protector configuration would look like

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_NONE is not set
  # CONFIG_CC_STACKPROTECTOR_REGULAR is not set
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_STACKPROTECTOR_AUTO=y

and when you ran this through "make oldconfig" with the Kbuild changes,
it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had
been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just
CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version
used to be disabled (because it was really enabled by AUTO), and would
disable it in the new config, resulting in:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

That's dangerously subtle - people could suddenly find themselves with
the weaker stack protector setup without even realizing.

The solution here is to just rename not just the old RECULAR stack
protector option, but also the strong one.  This does that by just
removing the CC_ prefix entirely for the user choices, because it really
is not about the compiler support (the compiler support now instead
automatially impacts _visibility_ of the options to users).

This results in "make oldconfig" actually asking the user for their
choice, so that we don't have any silent subtle security model changes.
The end result would generally look like this:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_STACKPROTECTOR=y
  CONFIG_STACKPROTECTOR_STRONG=y
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

where the "CC_" versions really are about internal compiler
infrastructure, not the user selections.

Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-14 12:21:18 +09:00
Linus Torvalds d82991a868 Merge branch 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull restartable sequence support from Thomas Gleixner:
 "The restartable sequences syscall (finally):

  After a lot of back and forth discussion and massive delays caused by
  the speculative distraction of maintainers, the core set of
  restartable sequences has finally reached a consensus.

  It comes with the basic non disputed core implementation along with
  support for arm, powerpc and x86 and a full set of selftests

  It was exposed to linux-next earlier this week, so it does not fully
  comply with the merge window requirements, but there is really no
  point to drag it out for yet another cycle"

* 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq/selftests: Provide Makefile, scripts, gitignore
  rseq/selftests: Provide parametrized tests
  rseq/selftests: Provide basic percpu ops test
  rseq/selftests: Provide basic test
  rseq/selftests: Provide rseq library
  selftests/lib.mk: Introduce OVERRIDE_TARGETS
  powerpc: Wire up restartable sequences system call
  powerpc: Add syscall detection for restartable sequences
  powerpc: Add support for restartable sequences
  x86: Wire up restartable sequence system call
  x86: Add support for restartable sequences
  arm: Wire up restartable sequences system call
  arm: Add syscall detection for restartable sequences
  arm: Add restartable sequences support
  rseq: Introduce restartable sequences system call
  uapi/headers: Provide types_32_64.h
2018-06-10 10:17:09 -07:00
Yang Shi 88aa7cc688 mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct
mmap_sem is on the hot path of kernel, and it very contended, but it is
abused too.  It is used to protect arg_start|end and evn_start|end when
reading /proc/$PID/cmdline and /proc/$PID/environ, but it doesn't make
sense since those proc files just expect to read 4 values atomically and
not related to VM, they could be set to arbitrary values by C/R.

And, the mmap_sem contention may cause unexpected issue like below:

INFO: task ps:14018 blocked for more than 120 seconds.
       Tainted: G            E 4.9.79-009.ali3000.alios7.x86_64 #1
 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
message.
 ps              D    0 14018      1 0x00000004
 Call Trace:
   schedule+0x36/0x80
   rwsem_down_read_failed+0xf0/0x150
   call_rwsem_down_read_failed+0x18/0x30
   down_read+0x20/0x40
   proc_pid_cmdline_read+0xd9/0x4e0
   __vfs_read+0x37/0x150
   vfs_read+0x96/0x130
   SyS_read+0x55/0xc0
   entry_SYSCALL_64_fastpath+0x1a/0xc5

Both Alexey Dobriyan and Michal Hocko suggested to use dedicated lock
for them to mitigate the abuse of mmap_sem.

So, introduce a new spinlock in mm_struct to protect the concurrent
access to arg_start|end, env_start|end and others, as well as replace
write map_sem to read to protect the race condition between prctl and
sys_brk which might break check_data_rlimit(), and makes prctl more
friendly to other VM operations.

This patch just eliminates the abuse of mmap_sem, but it can't resolve
the above hung task warning completely since the later
access_remote_vm() call needs acquire mmap_sem.  The mmap_sem
scalability issue will be solved in the future.

[yang.shi@linux.alibaba.com: add comment about mmap_sem and arg_lock]
  Link: http://lkml.kernel.org/r/1524077799-80690-1-git-send-email-yang.shi@linux.alibaba.com
Link: http://lkml.kernel.org/r/1523730291-109696-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-07 17:34:34 -07:00
Linus Torvalds 8b5c6a3a49 audit/stable-4.18 PR 20180605
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Merge tag 'audit-pr-20180605' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit

Pull audit updates from Paul Moore:
 "Another reasonable chunk of audit changes for v4.18, thirteen patches
  in total.

  The thirteen patches can mostly be broken down into one of four
  categories: general bug fixes, accessor functions for audit state
  stored in the task_struct, negative filter matches on executable
  names, and extending the (relatively) new seccomp logging knobs to the
  audit subsystem.

  The main driver for the accessor functions from Richard are the
  changes we're working on to associate audit events with containers,
  but I think they have some standalone value too so I figured it would
  be good to get them in now.

  The seccomp/audit patches from Tyler apply the seccomp logging
  improvements from a few releases ago to audit's seccomp logging;
  starting with this patchset the changes in
  /proc/sys/kernel/seccomp/actions_logged should apply to both the
  standard kernel logging and audit.

  As usual, everything passes the audit-testsuite and it happens to
  merge cleanly with your tree"

[ Heh, except it had trivial merge conflicts with the SELinux tree that
  also came in from Paul   - Linus ]

* tag 'audit-pr-20180605' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
  audit: Fix wrong task in comparison of session ID
  audit: use existing session info function
  audit: normalize loginuid read access
  audit: use new audit_context access funciton for seccomp_actions_logged
  audit: use inline function to set audit context
  audit: use inline function to get audit context
  audit: convert sessionid unset to a macro
  seccomp: Don't special case audited processes when logging
  seccomp: Audit attempts to modify the actions_logged sysctl
  seccomp: Configurable separator for the actions_logged string
  seccomp: Separate read and write code for actions_logged sysctl
  audit: allow not equal op for audit by executable
  audit: add syscall information to FEATURE_CHANGE records
2018-06-06 16:34:00 -07:00
Mathieu Desnoyers d7822b1e24 rseq: Introduce restartable sequences system call
Expose a new system call allowing each thread to register one userspace
memory area to be used as an ABI between kernel and user-space for two
purposes: user-space restartable sequences and quick access to read the
current CPU number value from user-space.

* Restartable sequences (per-cpu atomics)

Restartables sequences allow user-space to perform update operations on
per-cpu data without requiring heavy-weight atomic operations.

The restartable critical sections (percpu atomics) work has been started
by Paul Turner and Andrew Hunter. It lets the kernel handle restart of
critical sections. [1] [2] The re-implementation proposed here brings a
few simplifications to the ABI which facilitates porting to other
architectures and speeds up the user-space fast path.

Here are benchmarks of various rseq use-cases.

Test hardware:

arm32: ARMv7 Processor rev 4 (v7l) "Cubietruck", 2-core
x86-64: Intel E5-2630 v3@2.40GHz, 16-core, hyperthreading

The following benchmarks were all performed on a single thread.

* Per-CPU statistic counter increment

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:                344.0                 31.4          11.0
x86-64:                15.3                  2.0           7.7

* LTTng-UST: write event 32-bit header, 32-bit payload into tracer
             per-cpu buffer

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:               2502.0                 2250.0         1.1
x86-64:               117.4                   98.0         1.2

* liburcu percpu: lock-unlock pair, dereference, read/compare word

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:                751.0                 128.5          5.8
x86-64:                53.4                  28.6          1.9

* jemalloc memory allocator adapted to use rseq

Using rseq with per-cpu memory pools in jemalloc at Facebook (based on
rseq 2016 implementation):

The production workload response-time has 1-2% gain avg. latency, and
the P99 overall latency drops by 2-3%.

* Reading the current CPU number

Speeding up reading the current CPU number on which the caller thread is
running is done by keeping the current CPU number up do date within the
cpu_id field of the memory area registered by the thread. This is done
by making scheduler preemption set the TIF_NOTIFY_RESUME flag on the
current thread. Upon return to user-space, a notify-resume handler
updates the current CPU value within the registered user-space memory
area. User-space can then read the current CPU number directly from
memory.

Keeping the current cpu id in a memory area shared between kernel and
user-space is an improvement over current mechanisms available to read
the current CPU number, which has the following benefits over
alternative approaches:

- 35x speedup on ARM vs system call through glibc
- 20x speedup on x86 compared to calling glibc, which calls vdso
  executing a "lsl" instruction,
- 14x speedup on x86 compared to inlined "lsl" instruction,
- Unlike vdso approaches, this cpu_id value can be read from an inline
  assembly, which makes it a useful building block for restartable
  sequences.
- The approach of reading the cpu id through memory mapping shared
  between kernel and user-space is portable (e.g. ARM), which is not the
  case for the lsl-based x86 vdso.

On x86, yet another possible approach would be to use the gs segment
selector to point to user-space per-cpu data. This approach performs
similarly to the cpu id cache, but it has two disadvantages: it is
not portable, and it is incompatible with existing applications already
using the gs segment selector for other purposes.

Benchmarking various approaches for reading the current CPU number:

ARMv7 Processor rev 4 (v7l)
Machine model: Cubietruck
- Baseline (empty loop):                                    8.4 ns
- Read CPU from rseq cpu_id:                               16.7 ns
- Read CPU from rseq cpu_id (lazy register):               19.8 ns
- glibc 2.19-0ubuntu6.6 getcpu:                           301.8 ns
- getcpu system call:                                     234.9 ns

x86-64 Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz:
- Baseline (empty loop):                                    0.8 ns
- Read CPU from rseq cpu_id:                                0.8 ns
- Read CPU from rseq cpu_id (lazy register):                0.8 ns
- Read using gs segment selector:                           0.8 ns
- "lsl" inline assembly:                                   13.0 ns
- glibc 2.19-0ubuntu6 getcpu:                              16.6 ns
- getcpu system call:                                      53.9 ns

- Speed (benchmark taken on v8 of patchset)

Running 10 runs of hackbench -l 100000 seems to indicate, contrary to
expectations, that enabling CONFIG_RSEQ slightly accelerates the
scheduler:

Configuration: 2 sockets * 8-core Intel(R) Xeon(R) CPU E5-2630 v3 @
2.40GHz (directly on hardware, hyperthreading disabled in BIOS, energy
saving disabled in BIOS, turboboost disabled in BIOS, cpuidle.off=1
kernel parameter), with a Linux v4.6 defconfig+localyesconfig,
restartable sequences series applied.

* CONFIG_RSEQ=n

avg.:      41.37 s
std.dev.:   0.36 s

* CONFIG_RSEQ=y

avg.:      40.46 s
std.dev.:   0.33 s

- Size

On x86-64, between CONFIG_RSEQ=n/y, the text size increase of vmlinux is
567 bytes, and the data size increase of vmlinux is 5696 bytes.

[1] https://lwn.net/Articles/650333/
[2] http://www.linuxplumbersconf.org/2013/ocw/system/presentations/1695/original/LPC%20-%20PerCpu%20Atomics.pdf

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Chris Lameter <cl@linux.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Hunter <ahh@google.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Maurer <bmaurer@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20151027235635.16059.11630.stgit@pjt-glaptop.roam.corp.google.com
Link: http://lkml.kernel.org/r/20150624222609.6116.86035.stgit@kitami.mtv.corp.google.com
Link: https://lkml.kernel.org/r/20180602124408.8430-3-mathieu.desnoyers@efficios.com
2018-06-06 11:58:31 +02:00
Richard Guy Briggs c0b0ae8a87 audit: use inline function to set audit context
Recognizing that the audit context is an internal audit value, use an
access function to set the audit context pointer for the task
rather than reaching directly into the task struct to set it.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: merge fuzz in audit.h]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-05-14 17:45:21 -04:00
Kees Cook e01e80634e fork: unconditionally clear stack on fork
One of the classes of kernel stack content leaks[1] is exposing the
contents of prior heap or stack contents when a new process stack is
allocated.  Normally, those stacks are not zeroed, and the old contents
remain in place.  In the face of stack content exposure flaws, those
contents can leak to userspace.

Fixing this will make the kernel no longer vulnerable to these flaws, as
the stack will be wiped each time a stack is assigned to a new process.
There's not a meaningful change in runtime performance; it almost looks
like it provides a benefit.

Performing back-to-back kernel builds before:
	Run times: 157.86 157.09 158.90 160.94 160.80
	Mean: 159.12
	Std Dev: 1.54

and after:
	Run times: 159.31 157.34 156.71 158.15 160.81
	Mean: 158.46
	Std Dev: 1.46

Instead of making this a build or runtime config, Andy Lutomirski
recommended this just be enabled by default.

[1] A noisy search for many kinds of stack content leaks can be seen here:
https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=linux+kernel+stack+leak

I did some more with perf and cycle counts on running 100,000 execs of
/bin/true.

before:
Cycles: 218858861551 218853036130 214727610969 227656844122 224980542841
Mean:  221015379122.60
Std Dev: 4662486552.47

after:
Cycles: 213868945060 213119275204 211820169456 224426673259 225489986348
Mean:  217745009865.40
Std Dev: 5935559279.99

It continues to look like it's faster, though the deviation is rather
wide, but I'm not sure what I could do that would be less noisy.  I'm
open to ideas!

Link: http://lkml.kernel.org/r/20180221021659.GA37073@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-20 17:18:35 -07:00
Mark Rutland 3eda69c92d kernel/fork.c: detect early free of a live mm
KASAN splats indicate that in some cases we free a live mm, then
continue to access it, with potentially disastrous results.  This is
likely due to a mismatched mmdrop() somewhere in the kernel, but so far
the culprit remains elusive.

Let's have __mmdrop() verify that the mm isn't live for the current
task, similar to the existing check for init_mm.  This way, we can catch
this class of issue earlier, and without requiring KASAN.

Currently, idle_task_exit() leaves active_mm stale after it switches to
init_mm.  This isn't harmful, but will trigger the new assertions, so we
must adjust idle_task_exit() to update active_mm.

Link: http://lkml.kernel.org/r/20180312140103.19235-1-mark.rutland@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-05 21:36:27 -07:00