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  1. Nov 20, 2021
    • Nathan Chancellor's avatar
      hexagon: clean up timer-regs.h · 51f2ec59
      Nathan Chancellor authored 
      When building allmodconfig, there is a warning about TIMER_ENABLE being
redefined:

  drivers/clocksource/timer-oxnas-rps.c:39:9: error: 'TIMER_ENABLE' macro redefined [-Werror,-Wmacro-redefined]
  #define TIMER_ENABLE            BIT(7)
          ^
  arch/hexagon/include/asm/timer-regs.h:13:9: note: previous definition is here
  #define TIMER_ENABLE            0
           ^
  1 error generated.

The values in this header are only used in one file each, if they are
used at all.  Remove the header and sink all of the constants into their
respective files.

TCX0_CLK_RATE is only used in arch/hexagon/include/asm/timex.h

TIMER_ENABLE, RTOS_TIMER_INT, RTOS_TIMER_REGS_ADDR are only used in
arch/hexagon/kernel/time.c.

SLEEP_CLK_RATE and TIMER_CLR_ON_MATCH have both been unused since the
file's introduction in commit 71e4a47f ("Hexagon: Add time and timer
functions").

TIMER_ENABLE is redefined as BIT(0) so the shift is moved into the
definition, rather than its use.

Link: https://lkml.kernel.org/r/20211115174250.1994179-3-nathan@kernel.org


Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
Acked-by: default avatarBrian Cain <bcain@codeaurora.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      51f2ec59
    • Nathan Chancellor's avatar
      hexagon: export raw I/O routines for modules · ffb92ce8
      Nathan Chancellor authored 
      Patch series "Fixes for ARCH=hexagon allmodconfig", v2.

This series fixes some issues noticed with ARCH=hexagon allmodconfig.

This patch (of 3):

When building ARCH=hexagon allmodconfig, the following errors occur:

  ERROR: modpost: "__raw_readsl" [drivers/i3c/master/svc-i3c-master.ko] undefined!
  ERROR: modpost: "__raw_writesl" [drivers/i3c/master/dw-i3c-master.ko] undefined!
  ERROR: modpost: "__raw_readsl" [drivers/i3c/master/dw-i3c-master.ko] undefined!
  ERROR: modpost: "__raw_writesl" [drivers/i3c/master/i3c-master-cdns.ko] undefined!
  ERROR: modpost: "__raw_readsl" [drivers/i3c/master/i3c-master-cdns.ko] undefined!

Export these symbols so that modules can use them without any errors.

Link: https://lkml.kernel.org/r/20211115174250.1994179-1-nathan@kernel.org
Link: https://lkml.kernel.org/r/20211115174250.1994179-2-nathan@kernel.org
Fixes: 013bf24c

 ("Hexagon: Provide basic implementation and/or stubs for I/O routines.")
Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
Acked-by: default avatarBrian Cain <bcain@codeaurora.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ffb92ce8
    • Yunfeng Ye's avatar
      mm: emit the "free" trace report before freeing memory in kmem_cache_free() · 9a543f00
      Yunfeng Ye authored 
      After the memory is freed, it can be immediately allocated by other
CPUs, before the "free" trace report has been emitted.  This causes
inaccurate traces.

For example, if the following sequence of events occurs:

    CPU 0                 CPU 1

  (1) alloc xxxxxx
  (2) free  xxxxxx
                         (3) alloc xxxxxx
                         (4) free  xxxxxx

Then they will be inaccurately reported via tracing, so that they appear
to have happened in this order:

    CPU 0                 CPU 1

  (1) alloc xxxxxx
                         (2) alloc xxxxxx
  (3) free  xxxxxx
                         (4) free  xxxxxx

This makes it look like CPU 1 somehow managed to allocate memory that
CPU 0 still had allocated for itself.

In order to avoid this, emit the "free xxxxxx" tracing report just
before the actual call to free the memory, instead of just after it.

Link: https://lkml.kernel.org/r/374eb75d-7404-8721-4e1e-65b0e5b17279@huawei.com


Signed-off-by: default avatarYunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.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: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9a543f00
    • Alexander Mikhalitsyn's avatar
      shm: extend forced shm destroy to support objects from several IPC nses · 85b6d246
      Alexander Mikhalitsyn authored 
      Currently, the exit_shm() function not designed to work properly when
task->sysvshm.shm_clist holds shm objects from different IPC namespaces.

This is a real pain when sysctl kernel.shm_rmid_forced = 1, because it
leads to use-after-free (reproducer exists).

This is an attempt to fix the problem by extending exit_shm mechanism to
handle shm's destroy from several IPC ns'es.

To achieve that we do several things:

1. add a namespace (non-refcounted) pointer to the struct shmid_kernel

2. during new shm object creation (newseg()/shmget syscall) we
   initialize this pointer by current task IPC ns

3. exit_shm() fully reworked such that it traverses over all shp's in
   task->sysvshm.shm_clist and gets IPC namespace not from current task
   as it was before but from shp's object itself, then call
   shm_destroy(shp, ns).

Note: We need to be really careful here, because as it was said before
(1), our pointer to IPC ns non-refcnt'ed.  T...
      85b6d246
    • Alexander Mikhalitsyn's avatar
      ipc: WARN if trying to remove ipc object which is absent · 126e8bee
      Alexander Mikhalitsyn authored 
      Patch series "shm: shm_rmid_forced feature fixes".

Some time ago I met kernel crash after CRIU restore procedure,
fortunately, it was CRIU restore, so, I had dump files and could do
restore many times and crash reproduced easily.  After some
investigation I've constructed the minimal reproducer.  It was found
that it's use-after-free and it happens only if sysctl
kernel.shm_rmid_forced = 1.

The key of the problem is that the exit_shm() function not handles shp's
object destroy when task->sysvshm.shm_clist contains items from
different IPC namespaces.  In most cases this list will contain only
items from one IPC namespace.

How can this list contain object from different namespaces? The
exit_shm() function is designed to clean up this list always when
process leaves IPC namespace.  But we made a mistake a long time ago and
did not add a exit_shm() call into the setns() syscall procedures.

The first idea was just to add this call to setns() syscall but it
obviously changes semantics of setns() syscall and that's
userspace-visible change.  So, I gave up on this idea.

The first real attempt to address the issue was just to omit forced
destroy if we meet shp object not from current task IPC namespace [1].
But that was not the best idea because task->sysvshm.shm_clist was
protected by rwsem which belongs to current task IPC namespace.  It
means that list corruption may occur.

Second approach is just extend exit_shm() to properly handle shp's from
different IPC namespaces [2].  This is really non-trivial thing, I've
put a lot of effort into that but not believed that it's possible to
make it fully safe, clean and clear.

Thanks to the efforts of Manfred Spraul working an elegant solution was
designed.  Thanks a lot, Manfred!

Eric also suggested the way to address the issue in ("[RFC][PATCH] shm:
In shm_exit destroy all created and never attached segments") Eric's
idea was to maintain a list of shm_clists one per IPC namespace, use
lock-less lists.  But there is some extra memory consumption-related
concerns.

An alternative solution which was suggested by me was implemented in
("shm: reset shm_clist on setns but omit forced shm destroy").  The idea
is pretty simple, we add exit_shm() syscall to setns() but DO NOT
destroy shm segments even if sysctl kernel.shm_rmid_forced = 1, we just
clean up the task->sysvshm.shm_clist list.

This chages semantics of setns() syscall a little bit but in comparision
to the "naive" solution when we just add exit_shm() without any special
exclusions this looks like a safer option.

[1] https://lkml.org/lkml/2021/7/6/1108
[2] https://lkml.org/lkml/2021/7/14/736

This patch (of 2):

Let's produce a warning if we trying to remove non-existing IPC object
from IPC namespace kht/idr structures.

This allows us to catch possible bugs when the ipc_rmid() function was
called with inconsistent struct ipc_ids*, struct kern_ipc_perm*
arguments.

Link: https://lkml.kernel.org/r/20211027224348.611025-1-alexander.mikhalitsyn@virtuozzo.com
Link: https://lkml.kernel.org/r/20211027224348.611025-2-alexander.mikhalitsyn@virtuozzo.com


Co-developed-by: default avatarManfred Spraul <manfred@colorfullife.com>
Signed-off-by: default avatarManfred Spraul <manfred@colorfullife.com>
Signed-off-by: default avatarAlexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      126e8bee
    • Matthew Wilcox's avatar
      mm/swap.c:put_pages_list(): reinitialise the page list · 3cd018b4
      Matthew Wilcox authored 
      While free_unref_page_list() puts pages onto the CPU local LRU list, it
does not remove them from the list they were passed in on.  That makes
the list_head appear to be non-empty, and would lead to various
corruption problems if we didn't have an assertion that the list was
empty.

Reinitialise the list after calling free_unref_page_list() to avoid this
problem.

Link: https://lkml.kernel.org/r/YYp40A2lNrxaZji8@casper.infradead.org
Fixes: 988c69f1

 ("mm: optimise put_pages_list()")
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarSteve French <stfrench@microsoft.com>
Reported-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
Tested-by: default avatarSteve French <stfrench@microsoft.com>
Tested-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <smfrench@gmail.com>
Cc: Hyeoncheol Lee <hyc.lee@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3cd018b4
  3. Nov 19, 2021
  5. Nov 18, 2021

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