linux-toradex.git/net/core/netclassid_cgroup.c, branch v5.3.2

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

cgroup, netclassid: add a preemption point to write_classid

2018-10-23T19:58:17+00:00

We have seen a customer complaining about soft lockups on !PREEMPT
kernel config with 4.4 based kernel

[1072141.435366] NMI watchdog: BUG: soft lockup - CPU#21 stuck for 22s! [systemd:1]
[1072141.444090] Modules linked in: mpt3sas raid_class binfmt_misc af_packet 8021q garp mrp stp llc xfs libcrc32c bonding iscsi_ibft iscsi_boot_sysfs msr ext4 crc16 jbd2 mbcache cdc_ether usbnet mii joydev hid_generic usbhid intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel ipmi_ssif mgag200 i2c_algo_bit ttm ipmi_devintf drbg ixgbe drm_kms_helper vxlan ansi_cprng ip6_udp_tunnel drm aesni_intel udp_tunnel aes_x86_64 iTCO_wdt syscopyarea ptp xhci_pci lrw iTCO_vendor_support pps_core gf128mul ehci_pci glue_helper sysfillrect mdio pcspkr sb_edac ablk_helper cryptd ehci_hcd sysimgblt xhci_hcd fb_sys_fops edac_core mei_me lpc_ich ses usbcore enclosure dca mfd_core ipmi_si mei i2c_i801 scsi_transport_sas usb_common ipmi_msghandler shpchp fjes wmi processor button acpi_pad btrfs xor raid6_pq sd_mod crc32c_intel megaraid_sas sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua scsi_mod md_mod autofs4
[1072141.444146] Supported: Yes
[1072141.444149] CPU: 21 PID: 1 Comm: systemd Not tainted 4.4.121-92.80-default #1
[1072141.444150] Hardware name: LENOVO Lenovo System x3650 M5 -[5462P4U]- -[5462P4U]-/01GR451, BIOS -[TCE136H-2.70]- 06/13/2018
[1072141.444151] task: ffff880191bd0040 ti: ffff880191bd4000 task.ti: ffff880191bd4000
[1072141.444153] RIP: 0010:[]  [] update_classid_sock+0x29/0x40
[1072141.444157] RSP: 0018:ffff880191bd7d58  EFLAGS: 00000286
[1072141.444158] RAX: ffff883b177cb7c0 RBX: 0000000000000000 RCX: 0000000000000000
[1072141.444159] RDX: 00000000000009c7 RSI: ffff880191bd7d5c RDI: ffff8822e29bb200
[1072141.444160] RBP: ffff883a72230980 R08: 0000000000000101 R09: 0000000000000000
[1072141.444161] R10: 0000000000000008 R11: f000000000000000 R12: ffffffff815229d0
[1072141.444162] R13: 0000000000000000 R14: ffff881fd0a47ac0 R15: ffff880191bd7f28
[1072141.444163] FS:  00007f3e2f1eb8c0(0000) GS:ffff882000340000(0000) knlGS:0000000000000000
[1072141.444164] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1072141.444165] CR2: 00007f3e2f200000 CR3: 0000001ffea4e000 CR4: 00000000001606f0
[1072141.444166] Stack:
[1072141.444166]  ffffffa800000246 00000000000009c7 ffffffff8121d583 ffff8818312a05c0
[1072141.444168]  ffff8818312a1100 ffff880197c3b280 ffff881861422858 ffffffffffffffea
[1072141.444170]  ffffffff81522b1c ffffffff81d0ca20 ffff8817fa17b950 ffff883fdd8121e0
[1072141.444171] Call Trace:
[1072141.444179]  [] iterate_fd+0x53/0x80
[1072141.444182]  [] write_classid+0x4c/0x80
[1072141.444187]  [] cgroup_file_write+0x9b/0x100
[1072141.444193]  [] kernfs_fop_write+0x11b/0x150
[1072141.444198]  [] __vfs_write+0x26/0x100
[1072141.444201]  [] vfs_write+0x9d/0x190
[1072141.444203]  [] SyS_write+0x42/0xa0
[1072141.444207]  [] entry_SYSCALL_64_fastpath+0x1e/0xca
[1072141.445490] DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x1e/0xca

If a cgroup has many tasks with many open file descriptors then we would
end up in a large loop without any rescheduling point throught the
operation. Add cond_resched once per task.

Signed-off-by: Michal Hocko 
Signed-off-by: Tejun Heo

cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS

2017-07-21T15:14:51+00:00

css_task_iter currently always walks all tasks.  With the scheduled
cgroup v2 thread support, the iterator would need to handle multiple
types of iteration.  As a preparation, add @flags to
css_task_iter_start() and implement CSS_TASK_ITER_PROCS.  If the flag
is not specified, it walks all tasks as before.  When asserted, the
iterator only walks the group leaders.

For now, the only user of the flag is cgroup v2 "cgroup.procs" file
which no longer needs to skip non-leader tasks in cgroup_procs_next().
Note that cgroup v1 "cgroup.procs" can't use the group leader walk as
v1 "cgroup.procs" doesn't mean "list all thread group leaders in the
cgroup" but "list all thread group id's with any threads in the
cgroup".

While at it, update cgroup_procs_show() to use task_pid_vnr() instead
of task_tgid_vnr().  As the iteration guarantees that the function
only sees group leaders, this doesn't change the output and will allow
sharing the function for thread iteration.

Signed-off-by: Tejun Heo

cgroup, net_cls: iterate the fds of only the tasks which are being migrated

2017-03-22T17:32:46+00:00

The net_cls controller controls the classid field of each socket which
is associated with the cgroup.  Because the classid is per-socket
attribute, when a task migrates to another cgroup or the configured
classid of the cgroup changes, the controller needs to walk all
sockets and update the classid value, which was implemented by
3b13758f51de ("cgroups: Allow dynamically changing net_classid").

While the approach is not scalable, migrating tasks which have a lot
of fds attached to them is rare and the cost is born by the ones
initiating the operations.  However, for simplicity, both the
migration and classid config change paths call update_classid() which
scans all fds of all tasks in the target css.  This is an overkill for
the migration path which only needs to cover a much smaller subset of
tasks which are actually getting migrated in.

On cgroup v1, this can lead to unexpected scalability issues when one
tries to migrate a task or process into a net_cls cgroup which already
contains a lot of fds.  Even if the migration traget doesn't have many
to get scanned, update_classid() ends up scanning all fds in the
target cgroup which can be extremely numerous.

Unfortunately, on cgroup v2 which doesn't use net_cls, the problem is
even worse.  Before bfc2cf6f61fc ("cgroup: call subsys->*attach() only
for subsystems which are actually affected by migration"), cgroup core
would call the ->css_attach callback even for controllers which don't
see actual migration to a different css.

As net_cls is always disabled but still mounted on cgroup v2, whenever
a process is migrated on the cgroup v2 hierarchy, net_cls sees
identity migration from root to root and cgroup core used to call
->css_attach callback for those.  The net_cls ->css_attach ends up
calling update_classid() on the root net_cls css to which all
processes on the system belong to as the controller isn't used.  This
makes any cgroup v2 migration O(total_number_of_fds_on_the_system)
which is horrible and easily leads to noticeable stalls triggering RCU
stall warnings and so on.

The worst symptom is already fixed in upstream by bfc2cf6f61fc
("cgroup: call subsys->*attach() only for subsystems which are
actually affected by migration"); however, backporting that commit is
too invasive and we want to avoid other cases too.

This patch updates net_cls's cgrp_attach() to iterate fds of only the
processes which are actually getting migrated.  This removes the
surprising migration cost which is dependent on the total number of
fds in the target cgroup.  As this leaves write_classid() the only
user of update_classid(), open-code the helper into write_classid().

Reported-by: David Goode 
Fixes: 3b13758f51de ("cgroups: Allow dynamically changing net_classid")
Cc: stable@vger.kernel.org # v4.4+
Cc: Nina Schiff 
Cc: David S. Miller 
Signed-off-by: Tejun Heo 
Signed-off-by: David S. Miller

sched/headers: Prepare to move the task_lock()/unlock() APIs to

2017-03-02T07:42:38+00:00

But first update the code that uses these facilities with the
new header.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

core: remove unneded headers for net cgroup controllers.

2016-02-17T20:31:27+00:00

commit 3ed80a6 (cgroup: drop module support) made including
module.h redundant in the net cgroup controllers,
netclassid_cgroup.c and netprio_cgroup.c. This patch
removes them.

Signed-off-by: Rami Rosen 
Acked-by: Tejun Heo 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2015-12-18T03:08:28+00:00

Conflicts:
	drivers/net/geneve.c

Here we had an overlapping change, where in 'net' the extraneous stats
bump was being removed whilst in 'net-next' the final argument to
udp_tunnel6_xmit_skb() was being changed.

Signed-off-by: David S. Miller

sock, cgroup: add sock->sk_cgroup

2015-12-09T03:02:33+00:00

In cgroup v1, dealing with cgroup membership was difficult because the
number of membership associations was unbound.  As a result, cgroup v1
grew several controllers whose primary purpose is either tagging
membership or pull in configuration knobs from other subsystems so
that cgroup membership test can be avoided.

net_cls and net_prio controllers are examples of the latter.  They
allow configuring network-specific attributes from cgroup side so that
network subsystem can avoid testing cgroup membership; unfortunately,
these are not only cumbersome but also problematic.

Both net_cls and net_prio aren't properly hierarchical.  Both inherit
configuration from the parent on creation but there's no interaction
afterwards.  An ancestor doesn't restrict the behavior in its subtree
in anyway and configuration changes aren't propagated downwards.
Especially when combined with cgroup delegation, this is problematic
because delegatees can mess up whatever network configuration
implemented at the system level.  net_prio would allow the delegatees
to set whatever priority value regardless of CAP_NET_ADMIN and net_cls
the same for classid.

While it is possible to solve these issues from controller side by
implementing hierarchical allowable ranges in both controllers, it
would involve quite a bit of complexity in the controllers and further
obfuscate network configuration as it becomes even more difficult to
tell what's actually being configured looking from the network side.
While not much can be done for v1 at this point, as membership
handling is sane on cgroup v2, it'd be better to make cgroup matching
behave like other network matches and classifiers than introducing
further complications.

In preparation, this patch updates sock->sk_cgrp_data handling so that
it points to the v2 cgroup that sock was created in until either
net_prio or net_cls is used.  Once either of the two is used,
sock->sk_cgrp_data reverts to its previous role of carrying prioidx
and classid.  This is to avoid adding yet another cgroup related field
to struct sock.

As the mode switching can happen at most once per boot, the switching
mechanism is aimed at lowering hot path overhead.  It may leak a
finite, likely small, number of cgroup refs and report spurious
prioidx or classid on switching; however, dynamic updates of prioidx
and classid have always been racy and lossy - socks between creation
and fd installation are never updated, config changes don't update
existing sockets at all, and prioidx may index with dead and recycled
cgroup IDs.  Non-critical inaccuracies from small race windows won't
make any noticeable difference.

This patch doesn't make use of the pointer yet.  The following patch
will implement netfilter match for cgroup2 membership.

v2: Use sock_cgroup_data to avoid inflating struct sock w/ another
    cgroup specific field.

v3: Add comments explaining why sock_data_prioidx() and
    sock_data_classid() use different fallback values.

Signed-off-by: Tejun Heo 
Cc: Daniel Borkmann 
Cc: Daniel Wagner 
CC: Neil Horman 
Signed-off-by: David S. Miller

net: wrap sock->sk_cgrp_prioidx and ->sk_classid inside a struct

2015-12-09T03:02:33+00:00

Introduce sock->sk_cgrp_data which is a struct sock_cgroup_data.
->sk_cgroup_prioidx and ->sk_classid are moved into it.  The struct
and its accessors are defined in cgroup-defs.h.  This is to prepare
for overloading the fields with a cgroup pointer.

This patch mostly performs equivalent conversions but the followings
are noteworthy.

* Equality test before updating classid is removed from
  sock_update_classid().  This shouldn't make any noticeable
  difference and a similar test will be implemented on the helper side
  later.

* sock_update_netprioidx() now takes struct sock_cgroup_data and can
  be moved to netprio_cgroup.h without causing include dependency
  loop.  Moved.

* The dummy version of sock_update_netprioidx() converted to a static
  inline function while at it.

Signed-off-by: Tejun Heo 
Signed-off-by: David S. Miller

Merge branch 'master' into for-4.4-fixes

2015-12-07T15:09:03+00:00

The following commit which went into mainline through networking tree

  3b13758f51de ("cgroups: Allow dynamically changing net_classid")

conflicts in net/core/netclassid_cgroup.c with the following pending
fix in cgroup/for-4.4-fixes.

  1f7dd3e5a6e4 ("cgroup: fix handling of multi-destination migration from subtree_control enabling")

The former separates out update_classid() from cgrp_attach() and
updates it to walk all fds of all tasks in the target css so that it
can be used from both migration and config change paths.  The latter
drops @css from cgrp_attach().

Resolve the conflict by making cgrp_attach() call update_classid()
with the css from the first task.  We can revive @tset walking in
cgrp_attach() but given that net_cls is v1 only where there always is
only one target css during migration, this is fine.

Signed-off-by: Tejun Heo 
Reported-by: Stephen Rothwell 
Cc: Nina Schiff