linux-toradex.git/mm/vmpressure.c, branch v5.17

mm/vmpressure: fix data-race with memcg->socket_pressure

2021-11-06T20:30:40+00:00

When reading memcg->socket_pressure in mem_cgroup_under_socket_pressure()
and writing memcg->socket_pressure in vmpressure() at the same time, the
following data-race occurs:

  BUG: KCSAN: data-race in __sk_mem_reduce_allocated / vmpressure

  write to 0xffff8881286f4938 of 8 bytes by task 24550 on cpu 3:
   vmpressure+0x218/0x230 mm/vmpressure.c:307
   shrink_node_memcgs+0x2b9/0x410 mm/vmscan.c:2658
   shrink_node+0x9d2/0x11d0 mm/vmscan.c:2769
   shrink_zones+0x29f/0x470 mm/vmscan.c:2972
   do_try_to_free_pages+0x193/0x6e0 mm/vmscan.c:3027
   try_to_free_mem_cgroup_pages+0x1c0/0x3f0 mm/vmscan.c:3345
   reclaim_high mm/memcontrol.c:2440 [inline]
   mem_cgroup_handle_over_high+0x18b/0x4d0 mm/memcontrol.c:2624
   tracehook_notify_resume include/linux/tracehook.h:197 [inline]
   exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
   exit_to_user_mode_prepare+0x110/0x170 kernel/entry/common.c:191
   syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
   ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:289

  read to 0xffff8881286f4938 of 8 bytes by interrupt on cpu 1:
   mem_cgroup_under_socket_pressure include/linux/memcontrol.h:1483 [inline]
   sk_under_memory_pressure include/net/sock.h:1314 [inline]
   __sk_mem_reduce_allocated+0x1d2/0x270 net/core/sock.c:2696
   __sk_mem_reclaim+0x44/0x50 net/core/sock.c:2711
   sk_mem_reclaim include/net/sock.h:1490 [inline]
   ......
   net_rx_action+0x17a/0x480 net/core/dev.c:6864
   __do_softirq+0x12c/0x2af kernel/softirq.c:298
   run_ksoftirqd+0x13/0x20 kernel/softirq.c:653
   smpboot_thread_fn+0x33f/0x510 kernel/smpboot.c:165
   kthread+0x1fc/0x220 kernel/kthread.c:292
   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Fix it by using READ_ONCE() and WRITE_ONCE() to read and write
memcg->socket_pressure.

Link: https://lkml.kernel.org/r/20211025082843.671690-1-songyuanzheng@huawei.com
Signed-off-by: Yuanzheng Song 
Reviewed-by: Muchun Song 
Cc: Shakeel Butt 
Cc: Roman Gushchin 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: Matthew Wilcox (Oracle) 
Cc: Alex Shi 
Cc: Wei Yang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/vmpressure: replace vmpressure_to_css() with vmpressure_to_memcg()

2021-09-03T16:58:17+00:00

We can get memcg directly form vmpr instead of vmpr->memcg->css->memcg, so
add a new func helper vmpressure_to_memcg().  And no code will use
vmpressure_to_css(), so delete it.

Link: https://lkml.kernel.org/r/20210630112146.455103-1-suhui@zeku.com
Signed-off-by: Hui Su 
Acked-by: Michal Hocko 
Acked-by: Chris Down 
Cc: Johannes Weiner 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, memcg: add mem_cgroup_disabled checks in vmpressure and swap-related functions

2021-09-03T16:58:12+00:00

Add mem_cgroup_disabled check in vmpressure, mem_cgroup_uncharge_swap and
cgroup_throttle_swaprate functions.  This minimizes the memcg overhead in
the pagefault and exit_mmap paths when memcgs are disabled using
cgroup_disable=memory command-line option.

This change results in ~2.1% overhead reduction when running PFT test [1]
comparing {CONFIG_MEMCG=n, CONFIG_MEMCG_SWAP=n} against {CONFIG_MEMCG=y,
CONFIG_MEMCG_SWAP=y, cgroup_disable=memory} configuration on an 8-core
ARM64 Android device.

[1] https://lkml.org/lkml/2006/8/29/294 also used in mmtests suite

Link: https://lkml.kernel.org/r/20210713010934.299876-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Reviewed-by: Shakeel Butt 
Reviewed-by: Muchun Song 
Acked-by: Johannes Weiner 
Acked-by: Michal Hocko 
Cc: Alex Shi 
Cc: Alistair Popple 
Cc: David Hildenbrand 
Cc: Jens Axboe 
Cc: Joonsoo Kim 
Cc: Matthew Wilcox (Oracle) 
Cc: Miaohe Lin 
Cc: Minchan Kim 
Cc: Roman Gushchin 
Cc: Tejun Heo 
Cc: Wei Yang 
Cc: Yang Shi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: vmpressure: use mem_cgroup_is_root API

2020-04-02T16:35:31+00:00

Use mem_cgroup_is_root() API to check if memcg is root memcg instead of
open coding.

Signed-off-by: Yang Shi 
Signed-off-by: Andrew Morton 
Reviewed-by: Andrew Morton 
Reviewed-by: David Hildenbrand 
Acked-by: Michal Hocko 
Acked-by: David Rientjes 
Link: http://lkml.kernel.org/r/1581398649-125989-2-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds

mm: vmpressure: don't need call kfree if kstrndup fails

2020-04-02T16:35:31+00:00

When kstrndup fails, no memory was allocated and we can exit directly.

[david@redhat.com: reword changelog]
Signed-off-by: Yang Shi 
Signed-off-by: Andrew Morton 
Reviewed-by: Andrew Morton 
Reviewed-by: David Hildenbrand 
Acked-by: David Rientjes 
Link: http://lkml.kernel.org/r/1581398649-125989-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds

mm/vmpressure.c: fix a signedness bug in vmpressure_register_event()

2019-10-07T22:47:19+00:00

The "mode" and "level" variables are enums and in this context GCC will
treat them as unsigned ints so the error handling is never triggered.

I also removed the bogus initializer because it isn't required any more
and it's sort of confusing.

[akpm@linux-foundation.org: reduce implicit and explicit typecasting]
[akpm@linux-foundation.org: fix return value, add comment, per Matthew]
Link: http://lkml.kernel.org/r/20190925110449.GO3264@mwanda
Fixes: 3cadfa2b9497 ("mm/vmpressure.c: convert to use match_string() helper")
Signed-off-by: Dan Carpenter 
Reviewed-by: Andy Shevchenko 
Acked-by: David Rientjes 
Reviewed-by: Matthew Wilcox 
Cc: Greg Kroah-Hartman 
Cc: Thomas Gleixner 
Cc: Enrico Weigelt 
Cc: Kate Stewart 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 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 version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman

mm/vmpressure.c: convert to use match_string() helper

2018-06-08T00:34:36+00:00

The new helper returns index of the matching string in an array.  We are
going to use it here.

Link: http://lkml.kernel.org/r/20180503203206.44046-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko 
Acked-by: Michal Hocko 
Reviewed-by: Andrew Morton 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/vmpressure.c: use kstrndup instead of kmalloc+strncpy

2018-06-08T00:34:36+00:00

Using kstrndup() simplifies the code.

Link: http://lkml.kernel.org/r/20180503201807.24941-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko 
Acked-by: Michal Hocko 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, vmpressure: pass-through notification support

2017-07-10T23:32:31+00:00

By default, vmpressure events are not pass-through, i.e.  they propagate
up through the memcg hierarchy until an event notifier is found for any
threshold level.

This presents a difficulty when a thread waiting on a read(2) for a
vmpressure event cannot distinguish between local memory pressure and
memory pressure in a descendant memcg, especially when that thread may
not control the memcg hierarchy.

Consider a user-controlled child memcg with a smaller limit than a
top-level memcg controlled by the "Activity Manager" specified in
Documentation/cgroup-v1/memory.txt.  It may register for memory pressure
notification for descendant memcgs to make a policy decision: oom kill a
low priority job, increase the limit, decrease other limits, etc.  If it
registers for memory pressure notification on the top-level memcg, it
currently cannot distinguish between memory pressure in its own memcg or
a descendant memcg, which is user-controlled.

Conversely, if a user registers for memory pressure notification on
their own descendant memcg, the Activity Manager does not receive any
pressure notification for that child memcg hierarchy.  Vmpressure events
are not received for ancestor memcgs if the memcg experiencing pressure
have notifiers registered, perhaps outside the knowledge of the thread
waiting on read(2) at the top level.

Both of these are consequences of vmpressure notification not being
pass-through.

This implements a pass-through behavior for vmpressure events.  When
writing to control.event_control, vmpressure event handlers may
optionally specify a mode.  There are two new modes:

 - "hierarchy": always propagate memory pressure events up the hierarchy
   regardless if descendant memcgs have their own notifiers registered,
   and

 - "local": only receive notifications when the memcg for which the
   event is registered experiences memory pressure.

Of course, processes may register for one notification of "low,local",
for example, and another for "low".

If no mode is specified, the current behavior is maintained for
backwards compatibility.

See the change to Documentation/cgroup-v1/memory.txt for full
specification.

[dan.carpenter@oracle.com: free the same pointer we allocated]
  Link: http://lkml.kernel.org/r/20170613191820.GA20003@elgon.mountain
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1705311421320.8946@chino.kir.corp.google.com
Signed-off-by: David Rientjes 
Signed-off-by: Dan Carpenter 
Cc: Johannes Weiner 
Cc: Vlastimil Babka 
Cc: Minchan Kim 
Cc: Jonathan Corbet 
Cc: Anton Vorontsov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds