msm: memutils: memcpy, memmove, copy_page optimization

Preload farther to take advantage of the memory bus, and assume
64-byte cache lines.  Unroll some pairs of ldm/stm as well, for
unexplainable reasons.

Future enhancements should include,

- #define for how far to preload, possibly defined separately for
  memcpy, copy_*_user
- Tuning for misaligned buffers
- Tuning for memmove
- Tuning for small buffers
- Understanding mechanism behind ldm/stm unroll causing some gains
  in copy_to_user

BASELINE (msm8960pro):
======================================================================
memcpy 1000MB at 5MB       : took 808850 usec, bandwidth 1236.236 MB/s
copy_to_user 1000MB at 5MB : took 810071 usec, bandwidth 1234.234 MB/s
copy_from_user 1000MB at 5M: took 942926 usec, bandwidth 1060.060 MB/s
memmove 1000GB at 5MB      : took 848588 usec, bandwidth 1178.178 MB/s
copy_to_user 1000GB at 4kB : took 847916 usec, bandwidth 1179.179 MB/s
copy_from_user 1000GB at 4k: took 935113 usec, bandwidth 1069.069 MB/s
copy_page 1000GB at 4kB    : took 779459 usec, bandwidth 1282.282 MB/s

THIS PATCH:
======================================================================
memcpy 1000MB at 5MB       : took 346223 usec, bandwidth 2888.888 MB/s
copy_to_user 1000MB at 5MB : took 348084 usec, bandwidth 2872.872 MB/s
copy_from_user 1000MB at 5M: took 348176 usec, bandwidth 2872.872 MB/s
memmove 1000GB at 5MB      : took 348267 usec, bandwidth 2871.871 MB/s
copy_to_user 1000GB at 4kB : took 377018 usec, bandwidth 2652.652 MB/s
copy_from_user 1000GB at 4k: took 371829 usec, bandwidth 2689.689 MB/s
copy_page 1000GB at 4kB    : took 383763 usec, bandwidth 2605.605 MB/s

Change-Id: I843fe77192d61ce35a81e75d76fc09f0a472e98a
Signed-off-by: Chris Fries <C.Fries@motorola.com>
msm: memutils: memcpy, memmove optimization

1. To fit 8x26 64-bytes cache line size, we change preload steps as 64Bytes.
2. According to tune result, change preload distance as 5 cache lines.
3. According to tune result, re-arrange the ld/str order as back-to-back
   for copy_from_user.

The markable improvement:
	memcpy : 5%
	copy_to_user : 9%
	copy_from_user : 13%
	memmove : 37%

Raw data is as below:

BASELINE:
	memcpy 1000MB at 5MB       : took 1547098 usec, bandwidth 646.646 MB/s
	copy_to_user 1000MB at 5MB : took 1704308 usec, bandwidth 586.586 MB/s
	copy_from_user 1000MB at 5M: took 1777090 usec, bandwidth 562.562 MB/s
	memmove 1000GB at 5MB      : took 1066205 usec, bandwidth 937.937 MB/s
	copy_to_user 1000GB at 4kB : took 1774866 usec, bandwidth 563.563 MB/s
	copy_from_user 1000GB at 4k: took 1797654 usec, bandwidth 556.556 MB/s
	copy_page 1000GB at 4kB    : took 1644606 usec, bandwidth 608.608 MB/s
	memmove 1000GB at 4kB      : took 1236227 usec, bandwidth 808.808 MB/s

THIS PATCH:
	memcpy 1000MB at 5MB       : took 1475835 usec, bandwidth 677.677 MB/s
	copy_to_user 1000MB at 5MB : took 1559060 usec, bandwidth 641.641 MB/s
	copy_from_user 1000MB at 5M: took 1561603 usec, bandwidth 640.640 MB/s
	memmove 1000GB at 5MB      : took 861664 usec, bandwidth 1160.160 MB/s
	copy_to_user 1000GB at 4kB : took 1673501 usec, bandwidth 597.597 MB/s
	copy_from_user 1000GB at 4k: took 1674006 usec, bandwidth 597.597 MB/s
	copy_page 1000GB at 4kB    : took 1691358 usec, bandwidth 591.591 MB/s
	memmove 1000GB at 4kB      : took 882985 usec, bandwidth 1132.132 MB/s

Change-Id: I83bec3b7a9dd9cd88890eaa7ec423363e230a651
Signed-off-by: Hong-Mei Li <a21834@motorola.com>
Reviewed-on: http://gerrit.pcs.mot.com/550383
SLT-Approved: Slta Waiver <sltawvr@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Klocwork kwcheck <klocwork-kwcheck@sourceforge.mot.com>
Reviewed-by: Check Patch <CHEKPACH@motorola.com>
Reviewed-by: Yi-Wei Zhao <gbjc64@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
msm: memutils: memcpy, memmove Fix makefile issue
SELinux: add a ugly workaround to bail early when selinux tries to free a socket

That is still in use and it ends in a Kernel panic.
These lines are from opensource.samsung.com.
While this will most likely put a bandaid over this Kernel panic it does
not fix the bug so it might occur somewhere else if the
same conditions are met but since I have only seen panics from this hook then we may as well sleep in peace.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
SELinux: ipv4: Dump stack on attempt to release alive inet socket

We hide the bug, that will make SELinux bomb out. Let's dump the stack
when it happens to have at least a chance to find the cause.
config: b46-t1
tracing/sched: add load balancer tracepoint

When doing performance analysis it can be useful to see exactly
what is going on with the load balancer - when it runs and why
exactly it may not be redistributing load.

This additional tracepoint will show the idle context of the
load balance operation (idle, not idle, newly idle), various
values from the load balancing operation, the final result,
and the new balance interval.

Change-Id: I9e5c97ae3878bea44e60d189ff3cec2275f2c75e
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
CPU hotplug, debug: detect imbalance between get_online_cpus() and put_online_cpus()

The synchronization between CPU hotplug readers and writers is achieved
by means of refcounting, safeguarded by the cpu_hotplug.lock.

get_online_cpus() increments the refcount, whereas put_online_cpus()
decrements it.  If we ever hit an imbalance between the two, we end up
compromising the guarantees of the hotplug synchronization i.e, for
example, an extra call to put_online_cpus() can end up allowing a
hotplug reader to execute concurrently with a hotplug writer.

So, add a WARN_ON() in put_online_cpus() to detect such cases where the
refcount can go negative, and also attempt to fix it up, so that we can
continue to run.

Change-Id: I144efeaa5899a2e8a3cddd21f010679cbaaa2459
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 075663d19885eb3738fd2d7dbdb8947e12563b68
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>
nohz: Reduce overhead under high-freq idling patterns

One testbox of mine (Intel Nehalem, 16-way) uses MWAIT for its idle routine,
which apparently can break out of its idle loop rather frequently, with
high frequency.

In that case NO_HZ_FULL=y kernels show high ksoftirqd overhead and constant
context switching, because tick_nohz_stop_sched_tick() will, if
delta_jiffies == 0, mis-identify this as a timer event - activating the
TIMER_SOFTIRQ, which wakes up ksoftirqd.

Fix this by treating delta_jiffies == 0 the same way we treat other short
wakeups, delta_jiffies == 1.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
ARM: sched_clock: Load cycle count after epoch stabilizes

There is a small race between when the cycle count is read from
the hardware and when the epoch stabilizes. Consider this
scenario:

 CPU0                           CPU1
 ----                           ----
 cyc = read_sched_clock()
 cyc_to_sched_clock()
                                 update_sched_clock()
                                  ...
                                  cd.epoch_cyc = cyc;
  epoch_cyc = cd.epoch_cyc;
  ...
  epoch_ns + cyc_to_ns((cyc - epoch_cyc)

The cyc on cpu0 was read before the epoch changed. But we
calculate the nanoseconds based on the new epoch by subtracting
the new epoch from the old cycle count. Since epoch is most likely
larger than the old cycle count we calculate a large number that
will be converted to nanoseconds and added to epoch_ns, causing
time to jump forward too much.

Fix this problem by reading the hardware after the epoch has
stabilized.

Change-Id: I995133b229b2c2fedd5091406d1dc366d8bfff7b
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Git-commit: 336ae1180df5f69b9e0fb6561bec01c5f64361cf
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[sboyd: reworked for file movement kernel/time -> arm/kernel]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
block: do not notify urgent request, when flush with data in flight

MMC device driver implements URGENT request execution with priority
(using stop flow), as a result currently running (and prepared) request
may be reinserted back into I/O scheduler. This will break block layer
logic of flushes (flush request should not be inserted into I/O scheduler).

Block layer flush machinery keep q->flush_data_in_flight list updated with
started but not completed flush requests with data (REQ_FUA).

This change will not notify underling block device driver about pending
urgent request during flushes in flight.

Change-Id: I8b654925a3c989250fcb8f4f7c998795fb203923
Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
SELinux: Fix kernel BUG on empty security contexts.

Setting an empty security context (length=0) on a file will
lead to incorrectly dereferencing the type and other fields
of the security context structure, yielding a kernel BUG.
As a zero-length security context is never valid, just reject
all such security contexts whether coming from userspace
via setxattr or coming from the filesystem upon a getxattr
request by SELinux.

Setting a security context value (empty or otherwise) unknown to
SELinux in the first place is only possible for a root process
(CAP_MAC_ADMIN), and, if running SELinux in enforcing mode, only
if the corresponding SELinux mac_admin permission is also granted
to the domain by policy.  In Fedora policies, this is only allowed for
specific domains such as livecd for setting down security contexts
that are not defined in the build host policy.

[On Android, this can only be set by root/CAP_MAC_ADMIN processes,
and if running SELinux in enforcing mode, only if mac_admin permission
is granted in policy.  In Android 4.4, this would only be allowed for
root/CAP_MAC_ADMIN processes that are also in unconfined domains. In current
AOSP master, mac_admin is not allowed for any domains except the recovery
console which has a legitimate need for it.  The other potential vector
is mounting a maliciously crafted filesystem for which SELinux fetches
xattrs (e.g. an ext4 filesystem on a SDcard).  However, the end result is
only a local denial-of-service (DOS) due to kernel BUG.  This fix is
queued for 3.14.]

Reproducer:
su
setenforce 0
touch foo
setfattr -n security.selinux foo

Caveat:
Relabeling or removing foo after doing the above may not be possible
without booting with SELinux disabled.  Any subsequent access to foo
after doing the above will also trigger the BUG.

BUG output from Matthew Thode:
[  473.893141] ------------[ cut here ]------------
[  473.962110] kernel BUG at security/selinux/ss/services.c:654!
[  473.995314] invalid opcode: 0000 [#6] SMP
[  474.027196] Modules linked in:
[  474.058118] CPU: 0 PID: 8138 Comm: ls Tainted: G      D   I
3.13.0-grsec #1
[  474.116637] Hardware name: Supermicro X8ST3/X8ST3, BIOS 2.0
07/29/10
[  474.149768] task: ffff8805f50cd010 ti: ffff8805f50cd488 task.ti:
ffff8805f50cd488
[  474.183707] RIP: 0010:[<ffffffff814681c7>]  [<ffffffff814681c7>]
context_struct_compute_av+0xce/0x308
[  474.219954] RSP: 0018:ffff8805c0ac3c38  EFLAGS: 00010246
[  474.252253] RAX: 0000000000000000 RBX: ffff8805c0ac3d94 RCX:
0000000000000100
[  474.287018] RDX: ffff8805e8aac000 RSI: 00000000ffffffff RDI:
ffff8805e8aaa000
[  474.321199] RBP: ffff8805c0ac3cb8 R08: 0000000000000010 R09:
0000000000000006
[  474.357446] R10: 0000000000000000 R11: ffff8805c567a000 R12:
0000000000000006
[  474.419191] R13: ffff8805c2b74e88 R14: 00000000000001da R15:
0000000000000000
[  474.453816] FS:  00007f2e75220800(0000) GS:ffff88061fc00000(0000)
knlGS:0000000000000000
[  474.489254] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  474.522215] CR2: 00007f2e74716090 CR3: 00000005c085e000 CR4:
00000000000207f0
[  474.556058] Stack:
[  474.584325]  ffff8805c0ac3c98 ffffffff811b549b ffff8805c0ac3c98
ffff8805f1190a40
[  474.618913]  ffff8805a6202f08 ffff8805c2b74e88 00068800d0464990
ffff8805e8aac860
[  474.653955]  ffff8805c0ac3cb8 000700068113833a ffff880606c75060
ffff8805c0ac3d94
[  474.690461] Call Trace:
[  474.723779]  [<ffffffff811b549b>] ? lookup_fast+0x1cd/0x22a
[  474.778049]  [<ffffffff81468824>] security_compute_av+0xf4/0x20b
[  474.811398]  [<ffffffff8196f419>] avc_compute_av+0x2a/0x179
[  474.843813]  [<ffffffff8145727b>] avc_has_perm+0x45/0xf4
[  474.875694]  [<ffffffff81457d0e>] inode_has_perm+0x2a/0x31
[  474.907370]  [<ffffffff81457e76>] selinux_inode_getattr+0x3c/0x3e
[  474.938726]  [<ffffffff81455cf6>] security_inode_getattr+0x1b/0x22
[  474.970036]  [<ffffffff811b057d>] vfs_getattr+0x19/0x2d
[  475.000618]  [<ffffffff811b05e5>] vfs_fstatat+0x54/0x91
[  475.030402]  [<ffffffff811b063b>] vfs_lstat+0x19/0x1b
[  475.061097]  [<ffffffff811b077e>] SyS_newlstat+0x15/0x30
[  475.094595]  [<ffffffff8113c5c1>] ? __audit_syscall_entry+0xa1/0xc3
[  475.148405]  [<ffffffff8197791e>] system_call_fastpath+0x16/0x1b
[  475.179201] Code: 00 48 85 c0 48 89 45 b8 75 02 0f 0b 48 8b 45 a0 48
8b 3d 45 d0 b6 00 8b 40 08 89 c6 ff ce e8 d1 b0 06 00 48 85 c0 49 89 c7
75 02 <0f> 0b 48 8b 45 b8 4c 8b 28 eb 1e 49 8d 7d 08 be 80 01 00 00 e8
[  475.255884] RIP  [<ffffffff814681c7>]
context_struct_compute_av+0xce/0x308
[  475.296120]  RSP <ffff8805c0ac3c38>
[  475.328734] ---[ end trace f076482e9d754adc ]---

[sds:  commit message edited to note Android implications and
to generate a unique Change-Id for gerrit]

Change-Id: I4d5389f0cfa72b5f59dada45081fa47e03805413
Reported-by:  Matthew Thode <mthode@mthode.org>
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Cc: stable@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
sched: Avoid throttle_cfs_rq() racing with period_timer stopping

commit f9f9ffc237dd924f048204e8799da74f9ecf40cf upstream.

throttle_cfs_rq() doesn't check to make sure that period_timer is running,
and while update_curr/assign_cfs_runtime does, a concurrently running
period_timer on another cpu could cancel itself between this cpu's
update_curr and throttle_cfs_rq(). If there are no other cfs_rqs running
in the tg to restart the timer, this causes the cfs_rq to be stranded
forever.

Fix this by calling __start_cfs_bandwidth() in throttle if the timer is
inactive.

(Also add some sched_debug lines for cfs_bandwidth.)

Tested: make a run/sleep task in a cgroup, loop switching the cgroup
between 1ms/100ms quota and unlimited, checking for timer_active=0 and
throttled=1 as a failure. With the throttle_cfs_rq() change commented out
this fails, with the full patch it passes.

Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: pjt@google.com
Link: http://lkml.kernel.org/r/20131016181632.22647.84174.stgit@sword-of-the-dawn.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ext4: protect group inode free counting with group lock

commit 6f2e9f0e7d795214b9cf5a47724a273b705fd113 upstream.

Now when we set the group inode free count, we don't have a proper
group lock so that multiple threads may decrease the inode free
count at the same time. And e2fsck will complain something like:

Free inodes count wrong for group #1 (1, counted=0).
Fix? no

Free inodes count wrong for group #2 (3, counted=0).
Fix? no

Directories count wrong for group #2 (780, counted=779).
Fix? no

Free inodes count wrong for group #3 (2272, counted=2273).
Fix? no

So this patch try to protect it with the ext4_lock_group.

btw, it is found by xfstests test case 269 and the volume is
mkfsed with the parameter
"-O ^resize_inode,^uninit_bg,extent,meta_bg,flex_bg,ext_attr"
and I have run it 100 times and the error in e2fsck doesn't
show up again.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARM: smp: Wait just 1 second for other CPU to halt

Currently, the busyloop waiting for a 2nd CPU to stop takes about 4
seconds.  Adjust for the overhead of the loop by looping every 1ms
instead of 1us.

Signed-off-by: Chris Fries <C.Fries@motorola.com>
Reviewed-on: http://gerrit.pcs.mot.com/537864
SLT-Approved: Slta Waiver <sltawvr@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Check Patch <CHEKPACH@motorola.com>
Reviewed-by: Klocwork kwcheck <klocwork-kwcheck@sourceforge.mot.com>
Reviewed-by: Igor Kovalenko <cik009@motorola.com>
Reviewed-by: Russell Knize <rknize2@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
input: evdev: daisy-chain header and client buffers

The evdev driver calculates memory required to hold
client data using power-of-2 math, and then adds header
size, which pushes the request over the power of 2 and
requires 2x larger allocation.

Change the logic to daisy-chain the header and client array.
That way instead of single order4 allocation, we will make
order0+order2.

Signed-off-by: Igor Kovalenko <cik009@motorola.com>
SLT-Approved: Slta Waiver <sltawvr@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Christopher Fries <qcf001@motorola.com>
Reviewed-by: Jason Hrycay <jason.hrycay@motorola.com>
Reviewed-by: Klocwork kwcheck <klocwork-kwcheck@sourceforge.mot.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
cpuidle: remove cross-cpu IPI by new latency request.

when drivers request new latency requirement, it's not necessary to
immediately wake up another cpu by sending cross-cpu IPI, we can consider
the new latency to be taken into effect after next wakeup from idle,
this can save the unnecessary wakeup cost, and reduce the risk that
drivers may request latency in irq disabled context.

[<c08e0cc0>] (__irq_svc+0x40/0x70) from [<c00e801c>] (smp_call_function_single+0x16c/0x240)
[<c00e801c>] (smp_call_function_single+0x16c/0x240) from [<c00e855c>] (smp_call_function+0x40/0x6c)
[<c00e855c>] (smp_call_function+0x40/0x6c) from [<c0601c9c>] (cpuidle_latency_notify+0x18/0x20)
[<c0601c9c>] (cpuidle_latency_notify+0x18/0x20) from [<c00b7c28>] (blocking_notifier_call_chain+0x74/0x94)
[<c00b7c28>] (blocking_notifier_call_chain+0x74/0x94) from [<c00d563c>] (pm_qos_update_target+0xe0/0x128)
[<c00d563c>] (pm_qos_update_target+0xe0/0x128) from [<c0620d3c>] (msmsdcc_enable+0xac/0x158)
[<c0620d3c>] (msmsdcc_enable+0xac/0x158) from [<c06050e0>] (mmc_try_claim_host+0xb0/0xb8)
[<c06050e0>] (mmc_try_claim_host+0xb0/0xb8) from [<c0605318>] (mmc_start_bkops.part.15+0x50/0x2f4)
[<c0605318>] (mmc_start_bkops.part.15+0x50/0x2f4) from [<c00ab768>] (process_one_work+0x124/0x55c)
[<c00ab768>] (process_one_work+0x124/0x55c) from [<c00abfc8>] (worker_thread+0x178/0x45c)
[<c00abfc8>] (worker_thread+0x178/0x45c) from [<c00b0b24>] (kthread+0x84/0x90)
[<c00b0b24>] (kthread+0x84/0x90) from [<c000fdd4>] (kernel_thread_exit+0x0/0x8)
Disabling lock debugging due to kernel taint
coresight-etb coresight-etb.0: ETB aborted
Kernel panic - not syncing: softlockup: hung tasks

Signed-off-by: Guojian Chen <a21757@motorola.com>
Reviewed-on: http://gerrit.pcs.mot.com/532702
SLT-Approved: Slta Waiver <sltawvr@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Klocwork kwcheck <klocwork-kwcheck@sourceforge.mot.com>
Reviewed-by: Christopher Fries <qcf001@motorola.com>
Reviewed-by: David Ding <dding@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Revert "epoll: do not take globals epmutex for simple topologies fix"

This reverts commit 0d6c0e635bd4e8e1042acfadad96d7e008283008.
Revert "epoll: Do not take global 'epmutex' for simple topologies"

This reverts commit 59fc9b6fb2418d28b35ba77d989339b65fc4a285.
Revert "epoll: optimize EPOLL_CTL_DEL using rcu"

This reverts commit a182b3b17f67027ba1d543312cf168cd62b10fe6.