linux-toradex.git, branch v4.1.21

Linux 4.1.21

2016-04-03T22:26:26+00:00

Signed-off-by: Sasha Levin

perf/core: Fix perf_sched_count derailment

2016-03-24T12:40:21+00:00

[ Upstream commit 927a5570855836e5d5859a80ce7e91e963545e8f ]

The error path in perf_event_open() is such that asking for a sampling
event on a PMU that doesn't generate interrupts will end up in dropping
the perf_sched_count even though it hasn't been incremented for this
event yet.

Given a sufficient amount of these calls, we'll end up disabling
scheduler's jump label even though we'd still have active events in the
system, thereby facilitating the arrival of the infernal regions upon us.

I'm fixing this by moving account_event() inside perf_event_alloc().

Signed-off-by: Alexander Shishkin 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1456917854-29427-1-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar 
Signed-off-by: He Kuang 
Signed-off-by: Sasha Levin

perf: Cure event->pending_disable race

2016-03-24T12:40:21+00:00

[ Upstream commit 28a967c3a2f99fa3b5f762f25cb2a319d933571b ]

Because event_sched_out() checks event->pending_disable _before_
actually disabling the event, it can happen that the event fires after
it checks but before it gets disabled.

This would leave event->pending_disable set and the queued irq_work
will try and process it.

However, if the event trigger was during schedule(), the event might
have been de-scheduled by the time the irq_work runs, and
perf_event_disable_local() will fail.

Fix this by checking event->pending_disable _after_ we call
event->pmu->del(). This depends on the latter being a compiler
barrier, such that the compiler does not lift the load and re-creates
the problem.

Tested-by: Alexander Shishkin 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.040469884@infradead.org
Signed-off-by: Ingo Molnar 
Signed-off-by: He Kuang 
Signed-off-by: Sasha Levin

perf: Do not double free

2016-03-24T12:40:21+00:00

[ Upstream commit 130056275ade730e7a79c110212c8815202773ee ]

In case of: err_file: fput(event_file), we'll end up calling
perf_release() which in turn will free the event.

Do not then free the event _again_.

Tested-by: Alexander Shishkin 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.697350349@infradead.org
Signed-off-by: Ingo Molnar 
Signed-off-by: He Kuang 
Signed-off-by: Sasha Levin

arm64: replace read_lock to rcu lock in call_step_hook

2016-03-24T12:40:20+00:00

[ Upstream commit cf0a25436f05753aca5151891aea4fd130556e2a ]

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
in_atomic(): 1, irqs_disabled(): 128, pid: 383, name: sh
Preemption disabled at:[] kgdb_cpu_enter+0x158/0x6b8

CPU: 3 PID: 383 Comm: sh Tainted: G        W       4.1.13-rt13 #2
Hardware name: Freescale Layerscape 2085a RDB Board (DT)
Call trace:
[] dump_backtrace+0x0/0x128
[] show_stack+0x24/0x30
[] dump_stack+0x80/0xa0
[] ___might_sleep+0x18c/0x1a0
[] __rt_spin_lock+0x2c/0x40
[] rt_read_lock+0x40/0x58
[] single_step_handler+0x38/0xd8
[] do_debug_exception+0x58/0xb8
Exception stack(0xffff80834a1e7c80 to 0xffff80834a1e7da0)
7c80: ffffff9c ffffffff 92c23ba0 0000ffff 4a1e7e40 ffff8083 001bfcc4 ffff8000
7ca0: f2000400 00000000 00000000 00000000 4a1e7d80 ffff8083 0049501c ffff8000
7cc0: 00005402 00000000 00aaa210 ffff8000 4a1e7ea0 ffff8083 000833f4 ffff8000
7ce0: ffffff9c ffffffff 92c23ba0 0000ffff 4a1e7ea0 ffff8083 001bfcc0 ffff8000
7d00: 4a0fc400 ffff8083 00005402 00000000 4a1e7d40 ffff8083 00490324 ffff8000
7d20: ffffff9c 00000000 92c23ba0 0000ffff 000a0000 00000000 00000000 00000000
7d40: 00000008 00000000 00080000 00000000 92c23b8b 0000ffff 92c23b8e 0000ffff
7d60: 00000038 00000000 00001cb2 00000000 00000005 00000000 92d7b498 0000ffff
7d80: 01010101 01010101 92be9000 0000ffff 00000000 00000000 00000030 00000000
[] el1_dbg+0x18/0x6c

This issue is similar with 62c6c61("arm64: replace read_lock to rcu lock in
call_break_hook"), but comes to single_step_handler.

This also solves kgdbts boot test silent hang issue on 4.4 -rt kernel.

Signed-off-by: Yang Shi 
Acked-by: Will Deacon 
Signed-off-by: Catalin Marinas 
Signed-off-by: He Kuang 
Signed-off-by: Sasha Levin

arm64: replace read_lock to rcu lock in call_break_hook

2016-03-24T12:40:20+00:00

[ Upstream commit 62c6c61adbc623cdacf74b8f29c278e539060c48 ]

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
in_atomic(): 0, irqs_disabled(): 128, pid: 342, name: perf
1 lock held by perf/342:
 #0:  (break_hook_lock){+.+...}, at: [] call_break_hook+0x34/0xd0
irq event stamp: 62224
hardirqs last  enabled at (62223): [] __call_rcu.constprop.59+0x104/0x270
hardirqs last disabled at (62224): [] vprintk_emit+0x68/0x640
softirqs last  enabled at (0): [] copy_process.part.8+0x428/0x17f8
softirqs last disabled at (0): [<          (null)>]           (null)
CPU: 0 PID: 342 Comm: perf Not tainted 4.1.6-rt5 #4
Hardware name: linux,dummy-virt (DT)
Call trace:
[] dump_backtrace+0x0/0x128
[] show_stack+0x20/0x30
[] dump_stack+0x7c/0xa0
[] ___might_sleep+0x174/0x260
[] __rt_spin_lock+0x28/0x40
[] rt_read_lock+0x60/0x80
[] call_break_hook+0x30/0xd0
[] brk_handler+0x30/0x98
[] do_debug_exception+0x50/0xb8
Exception stack(0xffffffc00514fe30 to 0xffffffc00514ff50)
fe20:                                     00000000 00000000 c1594680 0000007f
fe40: ffffffff ffffffff 92063940 0000007f 0550dcd8 ffffffc0 00000000 00000000
fe60: 0514fe70 ffffffc0 000be1f8 ffffffc0 0514feb0 ffffffc0 0008948c ffffffc0
fe80: 00000004 00000000 0514fed0 ffffffc0 ffffffff ffffffff 9282a948 0000007f
fea0: 00000000 00000000 9282b708 0000007f c1592820 0000007f 00083914 ffffffc0
fec0: 00000000 00000000 00000010 00000000 00000064 00000000 00000001 00000000
fee0: 005101e0 00000000 c1594680 0000007f c1594740 0000007f ffffffd8 ffffff80
ff00: 00000000 00000000 00000000 00000000 c1594770 0000007f c1594770 0000007f
ff20: 00665e10 00000000 7f7f7f7f 7f7f7f7f 01010101 01010101 00000000 00000000
ff40: 928e4cc0 0000007f 91ff11e8 0000007f

call_break_hook is called in atomic context (hard irq disabled), so replace
the sleepable lock to rcu lock, replace relevant list operations to rcu
version and call synchronize_rcu() in unregister_break_hook().

And, replace write lock to spinlock in {un}register_break_hook.

Signed-off-by: Yang Shi 
Signed-off-by: Will Deacon 
Signed-off-by: He Kuang 
Signed-off-by: Sasha Levin

ext4: fix races of writeback with punch hole and zero range

2016-03-23T14:20:24+00:00

When doing delayed allocation, update of on-disk inode size is postponed
until IO submission time. However hole punch or zero range fallocate
calls can end up discarding the tail page cache page and thus on-disk
inode size would never be properly updated.

Make sure the on-disk inode size is updated before truncating page
cache.

Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Mingming Cao 
Signed-off-by: Sasha Levin

ext4: fix races between buffered IO and collapse / insert range

2016-03-23T14:20:24+00:00

Current code implementing FALLOC_FL_COLLAPSE_RANGE and
FALLOC_FL_INSERT_RANGE is prone to races with buffered writes and page
faults. If buffered write or write via mmap manages to squeeze between
filemap_write_and_wait_range() and truncate_pagecache() in the fallocate
implementations, the written data is simply discarded by
truncate_pagecache() although it should have been shifted.

Fix the problem by moving filemap_write_and_wait_range() call inside
i_mutex and i_mmap_sem. That way we are protected against races with
both buffered writes and page faults.

Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Mingming Cao 
Signed-off-by: Sasha Levin

ext4: move unlocked dio protection from ext4_alloc_file_blocks()

2016-03-23T14:20:24+00:00

Currently ext4_alloc_file_blocks() was handling protection against
unlocked DIO. However we now need to sometimes call it under i_mmap_sem
and sometimes not and DIO protection ranks above it (although strictly
speaking this cannot currently create any deadlocks). Also
ext4_zero_range() was actually getting & releasing unlocked DIO
protection twice in some cases. Luckily it didn't introduce any real bug
but it was a land mine waiting to be stepped on.  So move DIO protection
out from ext4_alloc_file_blocks() into the two callsites.

Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Mingming Cao 
Signed-off-by: Sasha Levin

ext4: fix races between page faults and hole punching

2016-03-23T14:20:24+00:00

Currently, page faults and hole punching are completely unsynchronized.
This can result in page fault faulting in a page into a range that we
are punching after truncate_pagecache_range() has been called and thus
we can end up with a page mapped to disk blocks that will be shortly
freed. Filesystem corruption will shortly follow. Note that the same
race is avoided for truncate by checking page fault offset against
i_size but there isn't similar mechanism available for punching holes.

Fix the problem by creating new rw semaphore i_mmap_sem in inode and
grab it for writing over truncate, hole punching, and other functions
removing blocks from extent tree and for read over page faults. We
cannot easily use i_data_sem for this since that ranks below transaction
start and we need something ranking above it so that it can be held over
the whole truncate / hole punching operation. Also remove various
workarounds we had in the code to reduce race window when page fault
could have created pages with stale mapping information.

Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Mingming Cao 
Signed-off-by: Sasha Levin