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  1. 10 8月, 2017 4 次提交
    • B
      locking/lockdep: Add a function building a chain between two classes · 49347a98
      由 Byungchul Park 提交于 
      Crossrelease needs to build a chain between two classes regardless of
their contexts. However, add_chain_cache() cannot be used for that
purpose since it assumes that it's called in the acquisition context
of the hlock. So this patch introduces a new function doing it.
Signed-off-by: NByungchul Park <byungchul.park@lge.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-3-git-send-email-byungchul.park@lge.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      49347a98
    • B
      locking/lockdep: Refactor lookup_chain_cache() · 545c23f2
      由 Byungchul Park 提交于 
      Currently, lookup_chain_cache() provides both 'lookup' and 'add'
functionalities in a function. However, each is useful. So this
patch makes lookup_chain_cache() only do 'lookup' functionality and
makes add_chain_cahce() only do 'add' functionality. And it's more
readable than before.
Signed-off-by: NByungchul Park <byungchul.park@lge.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-2-git-send-email-byungchul.park@lge.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      545c23f2
    • P
      locking/lockdep: Avoid creating redundant links · ae813308
      由 Peter Zijlstra 提交于 
      Two boots + a make defconfig, the first didn't have the redundant bit
in, the second did:

 lock-classes:                         1168       1169 [max: 8191]
 direct dependencies:                  7688       5812 [max: 32768]
 indirect dependencies:               25492      25937
 all direct dependencies:            220113     217512
 dependency chains:                    9005       9008 [max: 65536]
 dependency chain hlocks:             34450      34366 [max: 327680]
 in-hardirq chains:                      55         51
 in-softirq chains:                     371        378
 in-process chains:                    8579       8579
 stack-trace entries:                108073      88474 [max: 524288]
 combined max dependencies:       178738560  169094640

 max locking depth:                      15         15
 max bfs queue depth:                   320        329

 cyclic checks:                        9123       9190

 redundant checks:                                5046
 redundant links:                                 1828

 find-mask forwards checks:            2564       2599
 find-mask backwards checks:          39521      39789

So it saves nearly 2k links and a fair chunk of stack-trace entries, but
as expected, makes no real difference on the indirect dependencies.

At the same time, you see the max BFS depth increase, which is also
expected, although it could easily be boot variance -- these numbers are
not entirely stable between boots.

The down side is that the cycles in the graph become larger and thus
the reports harder to read.

XXX: do we want this as a CONFIG variable, implied by LOCKDEP_SMALL?
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: iamjoonsoo.kim@lge.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Link: http://lkml.kernel.org/r/20170303091338.GH6536@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
      ae813308
    • P
      locking/lockdep: Rework FS_RECLAIM annotation · d92a8cfc
      由 Peter Zijlstra 提交于 
      A while ago someone, and I cannot find the email just now, asked if we
could not implement the RECLAIM_FS inversion stuff with a 'fake' lock
like we use for other things like workqueues etc. I think this should
be possible which allows reducing the 'irq' states and will reduce the
amount of __bfs() lookups we do.

Removing the 1 IRQ state results in 4 less __bfs() walks per
dependency, improving lockdep performance. And by moving this
annotation out of the lockdep code it becomes easier for the mm people
to extend.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: iamjoonsoo.kim@lge.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      d92a8cfc
  3. 09 6月, 2017 2 次提交
  5. 04 5月, 2017 3 次提交
    • M
      mm: introduce memalloc_nofs_{save,restore} API · 7dea19f9
      由 Michal Hocko 提交于 
      GFP_NOFS context is used for the following 5 reasons currently:

 - to prevent from deadlocks when the lock held by the allocation
   context would be needed during the memory reclaim

 - to prevent from stack overflows during the reclaim because the
   allocation is performed from a deep context already

 - to prevent lockups when the allocation context depends on other
   reclaimers to make a forward progress indirectly

 - just in case because this would be safe from the fs POV

 - silence lockdep false positives

Unfortunately overuse of this allocation context brings some problems to
the MM.  Memory reclaim is much weaker (especially during heavy FS
metadata workloads), OOM killer cannot be invoked because the MM layer
doesn't have enough information about how much memory is freeable by the
FS layer.

In many cases it is far from clear why the weaker context is even used
and so it might be used unnecessarily.  We would like to get rid of
those as much as possible.  One way to do that is to use the flag in
scopes rather than isolated cases.  Such a scope is declared when really
necessary, tracked per task and all the allocation requests from within
the context will simply inherit the GFP_NOFS semantic.

Not only this is easier to understand and maintain because there are
much less problematic contexts than specific allocation requests, this
also helps code paths where FS layer interacts with other layers (e.g.
crypto, security modules, MM etc...) and there is no easy way to convey
the allocation context between the layers.

Introduce memalloc_nofs_{save,restore} API to control the scope of
GFP_NOFS allocation context.  This is basically copying
memalloc_noio_{save,restore} API we have for other restricted allocation
context GFP_NOIO.  The PF_MEMALLOC_NOFS flag already exists and it is
just an alias for PF_FSTRANS which has been xfs specific until recently.
There are no more PF_FSTRANS users anymore so let's just drop it.

PF_MEMALLOC_NOFS is now checked in the MM layer and drops __GFP_FS
implicitly same as PF_MEMALLOC_NOIO drops __GFP_IO.  memalloc_noio_flags
is renamed to current_gfp_context because it now cares about both
PF_MEMALLOC_NOFS and PF_MEMALLOC_NOIO contexts.  Xfs code paths preserve
their semantic.  kmem_flags_convert() doesn't need to evaluate the flag
anymore.

This patch shouldn't introduce any functional changes.

Let's hope that filesystems will drop direct GFP_NOFS (resp.  ~__GFP_FS)
usage as much as possible and only use a properly documented
memalloc_nofs_{save,restore} checkpoints where they are appropriate.

[akpm@linux-foundation.org: fix comment typo, reflow comment]
Link: http://lkml.kernel.org/r/20170306131408.9828-5-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7dea19f9
    • M
      lockdep: allow to disable reclaim lockup detection · 7e784422
      由 Michal Hocko 提交于 
      The current implementation of the reclaim lockup detection can lead to
false positives and those even happen and usually lead to tweak the code
to silence the lockdep by using GFP_NOFS even though the context can use
__GFP_FS just fine.

See

  http://lkml.kernel.org/r/20160512080321.GA18496@dastard

as an example.

  =================================
  [ INFO: inconsistent lock state ]
  4.5.0-rc2+ #4 Tainted: G           O
  ---------------------------------
  inconsistent {RECLAIM_FS-ON-R} -> {IN-RECLAIM_FS-W} usage.
  kswapd0/543 [HC0[0]:SC0[0]:HE1:SE1] takes:

  (&xfs_nondir_ilock_class){++++-+}, at: xfs_ilock+0x177/0x200 [xfs]

  {RECLAIM_FS-ON-R} state was registered at:
    mark_held_locks+0x79/0xa0
    lockdep_trace_alloc+0xb3/0x100
    kmem_cache_alloc+0x33/0x230
    kmem_zone_alloc+0x81/0x120 [xfs]
    xfs_refcountbt_init_cursor+0x3e/0xa0 [xfs]
    __xfs_refcount_find_shared+0x75/0x580 [xfs]
    xfs_refcount_find_shared+0x84/0xb0 [xfs]
    xfs_getbmap+0x608/0x8c0 [xfs]
    xfs_vn_fiemap+0xab/0xc0 [xfs]
    do_vfs_ioctl+0x498/0x670
    SyS_ioctl+0x79/0x90
    entry_SYSCALL_64_fastpath+0x12/0x6f

         CPU0
         ----
    lock(&xfs_nondir_ilock_class);
    <Interrupt>
      lock(&xfs_nondir_ilock_class);

   *** DEADLOCK ***

  3 locks held by kswapd0/543:

  stack backtrace:
  CPU: 0 PID: 543 Comm: kswapd0 Tainted: G           O    4.5.0-rc2+ #4
  Call Trace:
   lock_acquire+0xd8/0x1e0
   down_write_nested+0x5e/0xc0
   xfs_ilock+0x177/0x200 [xfs]
   xfs_reflink_cancel_cow_range+0x150/0x300 [xfs]
   xfs_fs_evict_inode+0xdc/0x1e0 [xfs]
   evict+0xc5/0x190
   dispose_list+0x39/0x60
   prune_icache_sb+0x4b/0x60
   super_cache_scan+0x14f/0x1a0
   shrink_slab.part.63.constprop.79+0x1e9/0x4e0
   shrink_zone+0x15e/0x170
   kswapd+0x4f1/0xa80
   kthread+0xf2/0x110
   ret_from_fork+0x3f/0x70

To quote Dave:
 "Ignoring whether reflink should be doing anything or not, that's a
  "xfs_refcountbt_init_cursor() gets called both outside and inside
  transactions" lockdep false positive case. The problem here is lockdep
  has seen this allocation from within a transaction, hence a GFP_NOFS
  allocation, and now it's seeing it in a GFP_KERNEL context. Also note
  that we have an active reference to this inode.

  So, because the reclaim annotations overload the interrupt level
  detections and it's seen the inode ilock been taken in reclaim
  ("interrupt") context, this triggers a reclaim context warning where
  it thinks it is unsafe to do this allocation in GFP_KERNEL context
  holding the inode ilock..."

This sounds like a fundamental problem of the reclaim lock detection.
It is really impossible to annotate such a special usecase IMHO unless
the reclaim lockup detection is reworked completely.  Until then it is
much better to provide a way to add "I know what I am doing flag" and
mark problematic places.  This would prevent from abusing GFP_NOFS flag
which has a runtime effect even on configurations which have lockdep
disabled.

Introduce __GFP_NOLOCKDEP flag which tells the lockdep gfp tracking to
skip the current allocation request.

While we are at it also make sure that the radix tree doesn't
accidentaly override tags stored in the upper part of the gfp_mask.

Link: http://lkml.kernel.org/r/20170306131408.9828-3-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Suggested-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7e784422
    • N
      lockdep: teach lockdep about memalloc_noio_save · 6d7225f0
      由 Nikolay Borisov 提交于 
      Patch series "scope GFP_NOFS api", v5.

This patch (of 7):

Commit 21caf2fc ("mm: teach mm by current context info to not do I/O
during memory allocation") added the memalloc_noio_(save|restore)
functions to enable people to modify the MM behavior by disabling I/O
during memory allocation.

This was further extended in commit 934f3072 ("mm: clear __GFP_FS
when PF_MEMALLOC_NOIO is set").

memalloc_noio_* functions prevent allocation paths recursing back into
the filesystem without explicitly changing the flags for every
allocation site.

However, lockdep hasn't been keeping up with the changes and it entirely
misses handling the memalloc_noio adjustments.  Instead, it is left to
the callers of __lockdep_trace_alloc to call the function after they
have shaven the respective GFP flags which can lead to false positives:

  =================================
   [ INFO: inconsistent lock state ]
   4.10.0-nbor #134 Not tainted
   ---------------------------------
   inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
   fsstress/3365 [HC0[0]:SC0[0]:HE1:SE1] takes:
    (&xfs_nondir_ilock_class){++++?.}, at: xfs_ilock+0x141/0x230
   {IN-RECLAIM_FS-W} state was registered at:
     __lock_acquire+0x62a/0x17c0
     lock_acquire+0xc5/0x220
     down_write_nested+0x4f/0x90
     xfs_ilock+0x141/0x230
     xfs_reclaim_inode+0x12a/0x320
     xfs_reclaim_inodes_ag+0x2c8/0x4e0
     xfs_reclaim_inodes_nr+0x33/0x40
     xfs_fs_free_cached_objects+0x19/0x20
     super_cache_scan+0x191/0x1a0
     shrink_slab+0x26f/0x5f0
     shrink_node+0xf9/0x2f0
     kswapd+0x356/0x920
     kthread+0x10c/0x140
     ret_from_fork+0x31/0x40
   irq event stamp: 173777
   hardirqs last  enabled at (173777): __local_bh_enable_ip+0x70/0xc0
   hardirqs last disabled at (173775): __local_bh_enable_ip+0x37/0xc0
   softirqs last  enabled at (173776): _xfs_buf_find+0x67a/0xb70
   softirqs last disabled at (173774): _xfs_buf_find+0x5db/0xb70

   other info that might help us debug this:
    Possible unsafe locking scenario:

          CPU0
          ----
     lock(&xfs_nondir_ilock_class);
     <Interrupt>
       lock(&xfs_nondir_ilock_class);

    *** DEADLOCK ***

   4 locks held by fsstress/3365:
    #0:  (sb_writers#10){++++++}, at: mnt_want_write+0x24/0x50
    #1:  (&sb->s_type->i_mutex_key#12){++++++}, at: vfs_setxattr+0x6f/0xb0
    #2:  (sb_internal#2){++++++}, at: xfs_trans_alloc+0xfc/0x140
    #3:  (&xfs_nondir_ilock_class){++++?.}, at: xfs_ilock+0x141/0x230

   stack backtrace:
   CPU: 0 PID: 3365 Comm: fsstress Not tainted 4.10.0-nbor #134
   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
   Call Trace:
    kmem_cache_alloc_node_trace+0x3a/0x2c0
    vm_map_ram+0x2a1/0x510
    _xfs_buf_map_pages+0x77/0x140
    xfs_buf_get_map+0x185/0x2a0
    xfs_attr_rmtval_set+0x233/0x430
    xfs_attr_leaf_addname+0x2d2/0x500
    xfs_attr_set+0x214/0x420
    xfs_xattr_set+0x59/0xb0
    __vfs_setxattr+0x76/0xa0
    __vfs_setxattr_noperm+0x5e/0xf0
    vfs_setxattr+0xae/0xb0
    setxattr+0x15e/0x1a0
    path_setxattr+0x8f/0xc0
    SyS_lsetxattr+0x11/0x20
    entry_SYSCALL_64_fastpath+0x23/0xc6

Let's fix this by making lockdep explicitly do the shaving of respective
GFP flags.

Fixes: 934f3072 ("mm: clear __GFP_FS when PF_MEMALLOC_NOIO is set")
Link: http://lkml.kernel.org/r/20170306131408.9828-2-mhocko@kernel.orgSigned-off-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6d7225f0
  7. 20 4月, 2017 1 次提交
  9. 16 3月, 2017 4 次提交
  11. 14 3月, 2017 1 次提交
    • D
      drm/i915: annote drop_caches debugfs interface with lockdep · 05df49e7
      由 Daniel Vetter 提交于 
      The trouble we have is that we can't really test all the shrinker
recursion stuff exhaustively in BAT because any kind of thrashing
stress test just takes too long.

But that leaves a really big gap open, since shrinker recursions are
one of the most annoying bugs. Now lockdep already has support for
checking allocation deadlocks:

- Direct reclaim paths are marked up with
  lockdep_set_current_reclaim_state() and
  lockdep_clear_current_reclaim_state().

- Any allocation paths are marked with lockdep_trace_alloc().

If we simply mark up our debugfs with the reclaim annotations, any
code and locks taken in there will automatically complete the picture
with any allocation paths we already have, as long as we have a simple
testcase in BAT which throws out a few objects using this interface.
Not stress test or thrashing needed at all.

v2: Need to EXPORT_SYMBOL_GPL to make it compile as a module.

v3: Fixup rebase fail (spotted by Chris).

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170312205340.16202-1-daniel.vetter@ffwll.chSigned-off-by: NDaniel Vetter <daniel.vetter@intel.com>
      05df49e7
  13. 02 3月, 2017 3 次提交
  15. 10 2月, 2017 1 次提交
  17. 24 1月, 2017 1 次提交
  19. 06 12月, 2016 1 次提交
    • D
      lockdep: Fix report formatting · f943fe0f
      由 Dmitry Vyukov 提交于 
      Since commit:

  4bcc595c ("printk: reinstate KERN_CONT for printing continuation lines")

printk() requires KERN_CONT to continue log messages. Lots of printk()
in lockdep.c and print_ip_sym() don't have it. As the result lockdep
reports are completely messed up.

Add missing KERN_CONT and inline print_ip_sym() where necessary.

Example of a messed up report:

  0-rc5+ #41 Not tainted
  -------------------------------------------------------
  syz-executor0/5036 is trying to acquire lock:
   (
  rtnl_mutex
  ){+.+.+.}
  , at:
  [<ffffffff86b3d6ac>] rtnl_lock+0x1c/0x20
  but task is already holding lock:
   (
  &net->packet.sklist_lock
  ){+.+...}
  , at:
  [<ffffffff873541a6>] packet_diag_dump+0x1a6/0x1920
  which lock already depends on the new lock.
  the existing dependency chain (in reverse order) is:
  -> #3
   (
  &net->packet.sklist_lock
  +.+...}
  ...

Without this patch all scripts that parse kernel bug reports are broken.
Signed-off-by: NDmitry Vyukov <dvyukov@google.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andreyknvl@google.com
Cc: aryabinin@virtuozzo.com
Cc: joe@perches.com
Cc: syzkaller@googlegroups.com
Link: http://lkml.kernel.org/r/1480343083-48731-1-git-send-email-dvyukov@google.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f943fe0f
  21. 30 11月, 2016 1 次提交
  23. 11 11月, 2016 1 次提交
  25. 08 6月, 2016 1 次提交
  27. 05 5月, 2016 1 次提交
    • P
      locking/lockdep, sched/core: Implement a better lock pinning scheme · e7904a28
      由 Peter Zijlstra 提交于 
      The problem with the existing lock pinning is that each pin is of
value 1; this mean you can simply unpin if you know its pinned,
without having any extra information.

This scheme generates a random (16 bit) cookie for each pin and
requires this same cookie to unpin. This means you have to keep the
cookie in context.

No objsize difference for !LOCKDEP kernels.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      e7904a28
  29. 23 4月, 2016 2 次提交
  31. 13 4月, 2016 1 次提交
  33. 04 4月, 2016 1 次提交
  35. 31 3月, 2016 1 次提交
  37. 16 3月, 2016 1 次提交
    • P
      tags: Fix DEFINE_PER_CPU expansions · 25528213
      由 Peter Zijlstra 提交于 
      $ make tags
  GEN     tags
ctags: Warning: drivers/acpi/processor_idle.c:64: null expansion of name pattern "\1"
ctags: Warning: drivers/xen/events/events_2l.c:41: null expansion of name pattern "\1"
ctags: Warning: kernel/locking/lockdep.c:151: null expansion of name pattern "\1"
ctags: Warning: kernel/rcu/rcutorture.c:133: null expansion of name pattern "\1"
ctags: Warning: kernel/rcu/rcutorture.c:135: null expansion of name pattern "\1"
ctags: Warning: kernel/workqueue.c:323: null expansion of name pattern "\1"
ctags: Warning: net/ipv4/syncookies.c:53: null expansion of name pattern "\1"
ctags: Warning: net/ipv6/syncookies.c:44: null expansion of name pattern "\1"
ctags: Warning: net/rds/page.c:45: null expansion of name pattern "\1"

Which are all the result of the DEFINE_PER_CPU pattern:

  scripts/tags.sh:200:	'/\<DEFINE_PER_CPU([^,]*, *\([[:alnum:]_]*\)/\1/v/'
  scripts/tags.sh:201:	'/\<DEFINE_PER_CPU_SHARED_ALIGNED([^,]*, *\([[:alnum:]_]*\)/\1/v/'

The below cures them. All except the workqueue one are within reasonable
distance of the 80 char limit. TJ do you have any preference on how to
fix the wq one, or shall we just not care its too long?
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      25528213
  39. 29 2月, 2016 2 次提交
    • I
      locking/lockdep: Detect chain_key collisions · 9e4e7554
      由 Ingo Molnar 提交于 
      Add detection for chain_key collision under CONFIG_DEBUG_LOCKDEP.
When a collision is detected the problem is reported and all lock
debugging is turned off.

Tested using liblockdep and the added tests before and after
applying the fix, confirming both that the code added for the
detection correctly reports the problem and that the fix actually
fixes it.

Tested tweaking lockdep to generate false collisions and
verified that the problem is reported and that lock debugging is
turned off.

Also tested with lockdep's test suite after applying the patch:

    [    0.000000] Good, all 253 testcases passed! |
Signed-off-by: NAlfredo Alvarez Fernandez <alfredoalvarezernandez@gmail.com>
Cc: Alfredo Alvarez Fernandez <alfredoalvarezfernandez@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: sasha.levin@oracle.com
Link: http://lkml.kernel.org/r/1455864533-7536-4-git-send-email-alfredoalvarezernandez@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      9e4e7554
    • A
      locking/lockdep: Prevent chain_key collisions · 5f18ab5c
      由 Alfredo Alvarez Fernandez 提交于 
      The chain_key hashing macro iterate_chain_key(key1, key2) does not
generate a new different value if both key1 and key2 are 0. In that
case the generated value is again 0. This can lead to collisions which
can result in lockdep not detecting deadlocks or circular
dependencies.

Avoid the problem by using class_idx (1-based) instead of class id
(0-based) as an input for the hashing macro 'key2' in
iterate_chain_key(key1, key2).

The use of class id created collisions in cases like the following:

1.- Consider an initial state in which no class has been acquired yet.
Under these circumstances an AA deadlock will not be detected by
lockdep:

  lock  [key1,key2]->new key  (key1=old chain_key, key2=id)
  --------------------------
  A     [0,0]->0
  A     [0,0]->0 (collision)

  The newly generated chain_key collides with the one used before and as
  a result the check for a deadlock is skipped

  A simple test using liblockdep and a pthread mutex confirms the
  problem: (omitting stack traces)

    new class 0xe15038: 0x7ffc64950f20
    acquire class [0xe15038] 0x7ffc64950f20
    acquire class [0xe15038] 0x7ffc64950f20
    hash chain already cached, key: 0000000000000000 tail class:
    [0xe15038] 0x7ffc64950f20

2.- Consider an ABBA in 2 different tasks and no class yet acquired.

  T1 [key1,key2]->new key     T2[key1,key2]->new key
  --                          --
  A [0,0]->0

                              B [0,1]->1

  B [0,1]->1  (collision)

                              A

In this case the collision prevents lockdep from creating the new
dependency A->B. This in turn results in lockdep not detecting the
circular dependency when T2 acquires A.
Signed-off-by: NAlfredo Alvarez Fernandez <alfredoalvarezernandez@gmail.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: sasha.levin@oracle.com
Link: http://lkml.kernel.org/r/1455147212-2389-4-git-send-email-alfredoalvarezernandez@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      5f18ab5c
  41. 12 2月, 2016 1 次提交
    • A
      kernel/locking/lockdep.c: convert hash tables to hlists · 4a389810
      由 Andrew Morton 提交于 
      Mike said:

: CONFIG_UBSAN_ALIGNMENT breaks x86-64 kernel with lockdep enabled, i.  e
: kernel with CONFIG_UBSAN_ALIGNMENT fails to load without even any error
: message.
:
: The problem is that ubsan callbacks use spinlocks and might be called
: before lockdep is initialized.  Particularly this line in the
: reserve_ebda_region function causes problem:
:
: lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
:
: If i put lockdep_init() before reserve_ebda_region call in
: x86_64_start_reservations kernel loads well.

Fix this ordering issue permanently: change lockdep so that it uses
hlists for the hash tables.  Unlike a list_head, an hlist_head is in its
initialized state when it is all-zeroes, so lockdep is ready for
operation immediately upon boot - lockdep_init() need not have run.

The patch will also save some memory.

lockdep_init() and lockdep_initialized can be done away with now - a 4.6
patch has been prepared to do this.
Reported-by: NMike Krinkin <krinkin.m.u@gmail.com>
Suggested-by: NMike Krinkin <krinkin.m.u@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4a389810
  43. 09 2月, 2016 3 次提交
    • A
      locking/lockdep: Eliminate lockdep_init() · 06bea3db
      由 Andrey Ryabinin 提交于 
      Lockdep is initialized at compile time now.  Get rid of lockdep_init().
Signed-off-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Krinkin <krinkin.m.u@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: mm-commits@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      06bea3db
    • A
      locking/lockdep: Convert hash tables to hlists · a63f38cc
      由 Andrew Morton 提交于 
      Mike said:

: CONFIG_UBSAN_ALIGNMENT breaks x86-64 kernel with lockdep enabled, i.e.
: kernel with CONFIG_UBSAN_ALIGNMENT=y fails to load without even any error
: message.
:
: The problem is that ubsan callbacks use spinlocks and might be called
: before lockdep is initialized.  Particularly this line in the
: reserve_ebda_region function causes problem:
:
: lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
:
: If i put lockdep_init() before reserve_ebda_region call in
: x86_64_start_reservations kernel loads well.

Fix this ordering issue permanently: change lockdep so that it uses hlists
for the hash tables.  Unlike a list_head, an hlist_head is in its
initialized state when it is all-zeroes, so lockdep is ready for operation
immediately upon boot - lockdep_init() need not have run.

The patch will also save some memory.

Probably lockdep_init() and lockdep_initialized can be done away with now.
Suggested-by: NMike Krinkin <krinkin.m.u@gmail.com>
Reported-by: NMike Krinkin <krinkin.m.u@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: mm-commits@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      a63f38cc
    • D
      locking/lockdep: Fix stack trace caching logic · 8a5fd564
      由 Dmitry Vyukov 提交于 
      check_prev_add() caches saved stack trace in static trace variable
to avoid duplicate save_trace() calls in dependencies involving trylocks.
But that caching logic contains a bug. We may not save trace on first
iteration due to early return from check_prev_add(). Then on the
second iteration when we actually need the trace we don't save it
because we think that we've already saved it.

Let check_prev_add() itself control when stack is saved.

There is another bug. Trace variable is protected by graph lock.
But we can temporary release graph lock during printing.

Fix this by invalidating cached stack trace when we release graph lock.
Signed-off-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: glider@google.com
Cc: kcc@google.com
Cc: peter@hurleysoftware.com
Cc: sasha.levin@oracle.com
Link: http://lkml.kernel.org/r/1454593240-121647-1-git-send-email-dvyukov@google.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      8a5fd564
  45. 23 11月, 2015 1 次提交
    • P
      treewide: Remove old email address · 90eec103
      由 Peter Zijlstra 提交于 
      There were still a number of references to my old Red Hat email
address in the kernel source. Remove these while keeping the
Red Hat copyright notices intact.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      90eec103
  47. 07 11月, 2015 1 次提交
    • M
      mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep... · d0164adc
      由 Mel Gorman 提交于 
      mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd

__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d0164adc
  49. 23 9月, 2015 1 次提交