linux.git/mm/memcontrol.c, branch v5.11

Revert "mm: memcontrol: avoid workload stalls when lowering memory.high"

2021-02-10T01:26:44+00:00

This reverts commit 536d3bf261a2fc3b05b3e91e7eef7383443015cf, as it can
cause writers to memory.high to get stuck in the kernel forever,
performing page reclaim and consuming excessive amounts of CPU cycles.

Before the patch, a write to memory.high would first put the new limit
in place for the workload, and then reclaim the requested delta.  After
the patch, the kernel tries to reclaim the delta before putting the new
limit into place, in order to not overwhelm the workload with a sudden,
large excess over the limit.  However, if reclaim is actively racing
with new allocations from the uncurbed workload, it can keep the write()
working inside the kernel indefinitely.

This is causing problems in Facebook production.  A privileged
system-level daemon that adjusts memory.high for various workloads
running on a host can get unexpectedly stuck in the kernel and
essentially turn into a sort of involuntary kswapd for one of the
workloads.  We've observed that daemon busy-spin in a write() for
minutes at a time, neglecting its other duties on the system, and
expending privileged system resources on behalf of a workload.

To remedy this, we have first considered changing the reclaim logic to
break out after a couple of loops - whether the workload has converged
to the new limit or not - and bound the write() call this way.  However,
the root cause that inspired the sequence change in the first place has
been fixed through other means, and so a revert back to the proven
limit-setting sequence, also used by memory.max, is preferable.

The sequence was changed to avoid extreme latencies in the workload when
the limit was lowered: the sudden, large excess created by the limit
lowering would erroneously trigger the penalty sleeping code that is
meant to throttle excessive growth from below.  Allocating threads could
end up sleeping long after the write() had already reclaimed the delta
for which they were being punished.

However, erroneous throttling also caused problems in other scenarios at
around the same time.  This resulted in commit b3ff92916af3 ("mm, memcg:
reclaim more aggressively before high allocator throttling"), included
in the same release as the offending commit.  When allocating threads
now encounter large excess caused by a racing write() to memory.high,
instead of entering punitive sleeps, they will simply be tasked with
helping reclaim down the excess, and will be held no longer than it
takes to accomplish that.  This is in line with regular limit
enforcement - i.e.  if the workload allocates up against or over an
otherwise unchanged limit from below.

With the patch breaking userspace, and the root cause addressed by other
means already, revert it again.

Link: https://lkml.kernel.org/r/20210122184341.292461-1-hannes@cmpxchg.org
Fixes: 536d3bf261a2 ("mm: memcontrol: avoid workload stalls when lowering memory.high")
Signed-off-by: Johannes Weiner 
Reported-by: Tejun Heo 
Acked-by: Chris Down 
Acked-by: Michal Hocko 
Cc: Roman Gushchin 
Cc: Shakeel Butt 
Cc: Michal Koutný 
Cc: 	[5.8+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: memcg/slab: optimize objcg stock draining

2021-01-24T17:20:52+00:00

Imran Khan reported a 16% regression in hackbench results caused by the
commit f2fe7b09a52b ("mm: memcg/slab: charge individual slab objects
instead of pages").  The regression is noticeable in the case of a
consequent allocation of several relatively large slab objects, e.g.
skb's.  As soon as the amount of stocked bytes exceeds PAGE_SIZE,
drain_obj_stock() and __memcg_kmem_uncharge() are called, and it leads
to a number of atomic operations in page_counter_uncharge().

The corresponding call graph is below (provided by Imran Khan):

  |__alloc_skb
  |    |
  |    |__kmalloc_reserve.isra.61
  |    |    |
  |    |    |__kmalloc_node_track_caller
  |    |    |    |
  |    |    |    |slab_pre_alloc_hook.constprop.88
  |    |    |     obj_cgroup_charge
  |    |    |    |    |
  |    |    |    |    |__memcg_kmem_charge
  |    |    |    |    |    |
  |    |    |    |    |    |page_counter_try_charge
  |    |    |    |    |
  |    |    |    |    |refill_obj_stock
  |    |    |    |    |    |
  |    |    |    |    |    |drain_obj_stock.isra.68
  |    |    |    |    |    |    |
  |    |    |    |    |    |    |__memcg_kmem_uncharge
  |    |    |    |    |    |    |    |
  |    |    |    |    |    |    |    |page_counter_uncharge
  |    |    |    |    |    |    |    |    |
  |    |    |    |    |    |    |    |    |page_counter_cancel
  |    |    |    |
  |    |    |    |
  |    |    |    |__slab_alloc
  |    |    |    |    |
  |    |    |    |    |___slab_alloc
  |    |    |    |    |
  |    |    |    |slab_post_alloc_hook

Instead of directly uncharging the accounted kernel memory, it's
possible to refill the generic page-sized per-cpu stock instead.  It's a
much faster operation, especially on a default hierarchy.  As a bonus,
__memcg_kmem_uncharge_page() will also get faster, so the freeing of
page-sized kernel allocations (e.g.  large kmallocs) will become faster.

A similar change has been done earlier for the socket memory by the
commit 475d0487a2ad ("mm: memcontrol: use per-cpu stocks for socket
memory uncharging").

Link: https://lkml.kernel.org/r/20210106042239.2860107-1-guro@fb.com
Fixes: f2fe7b09a52b ("mm: memcg/slab: charge individual slab objects instead of pages")
Signed-off-by: Roman Gushchin 
Reported-by: Imran Khan 
Tested-by: Imran Khan 
Reviewed-by: Shakeel Butt 
Reviewed-by: Michal Koutn 
Cc: Michal Koutný 
Cc: Johannes Weiner 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memcontrol:rewrite mem_cgroup_page_lruvec()

2020-12-19T19:18:37+00:00

mem_cgroup_page_lruvec() in memcontrol.c and mem_cgroup_lruvec() in
memcontrol.h is very similar except for the param(page and memcg) which
also can be convert to each other.

So rewrite mem_cgroup_page_lruvec() with mem_cgroup_lruvec().

[alex.shi@linux.alibaba.com: add missed warning in mem_cgroup_lruvec]
  Link: https://lkml.kernel.org/r/94f17bb7-ec61-5b72-3555-fabeb5a4d73b@linux.alibaba.com
[lstoakes@gmail.com: warn on missing memcg on mem_cgroup_page_lruvec()]
  Link: https://lkml.kernel.org/r/20201125112202.387009-1-lstoakes@gmail.com

Link: https://lkml.kernel.org/r/20201108143731.GA74138@rlk
Signed-off-by: Hui Su 
Signed-off-by: Alex Shi 
Signed-off-by: Lorenzo Stoakes 
Acked-by: Michal Hocko 
Acked-by: Johannes Weiner 
Reviewed-by: Shakeel Butt 
Acked-by: Roman Gushchin 
Cc: Vladimir Davydov 
Cc: Yafang Shao 
Cc: Chris Down 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memcg: warning on !memcg after readahead page charged

2020-12-19T19:18:37+00:00

Add VM_WARN_ON_ONCE_PAGE() macro.

Since readahead page is charged on memcg too, in theory we don't have to
check this exception now.  Before safely remove them all, add a warning
for the unexpected !memcg.

Link: https://lkml.kernel.org/r/1604283436-18880-3-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi 
Acked-by: Michal Hocko 
Acked-by: Hugh Dickins 
Acked-by: Johannes Weiner 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memcg: bail early from swap accounting if memcg disabled

2020-12-19T19:18:37+00:00

Patch series "bail out early for memcg disable".

These 2 patches are indepenedent from per memcg lru lock, and may
encounter unexpected warning, so let's move out them from per memcg
lru locking patchset.

This patch (of 2):

We could bail out early when memcg wasn't enabled.

Link: https://lkml.kernel.org/r/1604283436-18880-1-git-send-email-alex.shi@linux.alibaba.com
Link: https://lkml.kernel.org/r/1604283436-18880-2-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi 
Reviewed-by: Roman Gushchin 
Acked-by: Michal Hocko 
Acked-by: Hugh Dickins 
Acked-by: Johannes Weiner 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2020-12-15T22:55:10+00:00

Merge more updates from Andrew Morton:
 "More MM work: a memcg scalability improvememt"

* emailed patches from Andrew Morton :
  mm/lru: revise the comments of lru_lock
  mm/lru: introduce relock_page_lruvec()
  mm/lru: replace pgdat lru_lock with lruvec lock
  mm/swap.c: serialize memcg changes in pagevec_lru_move_fn
  mm/compaction: do page isolation first in compaction
  mm/lru: introduce TestClearPageLRU()
  mm/mlock: remove __munlock_isolate_lru_page()
  mm/mlock: remove lru_lock on TestClearPageMlocked
  mm/vmscan: remove lruvec reget in move_pages_to_lru
  mm/lru: move lock into lru_note_cost
  mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn
  mm/memcg: add debug checking in lock_page_memcg
  mm: page_idle_get_page() does not need lru_lock
  mm/rmap: stop store reordering issue on page->mapping
  mm/vmscan: remove unnecessary lruvec adding
  mm/thp: narrow lru locking
  mm/thp: simplify lru_add_page_tail()
  mm/thp: use head for head page in lru_add_page_tail()
  mm/thp: move lru_add_page_tail() to huge_memory.c

mm/lru: replace pgdat lru_lock with lruvec lock

2020-12-15T22:48:04+00:00

This patch moves per node lru_lock into lruvec, thus bring a lru_lock for
each of memcg per node.  So on a large machine, each of memcg don't have
to suffer from per node pgdat->lru_lock competition.  They could go fast
with their self lru_lock.

After move memcg charge before lru inserting, page isolation could
serialize page's memcg, then per memcg lruvec lock is stable and could
replace per node lru lock.

In isolate_migratepages_block(), compact_unlock_should_abort and
lock_page_lruvec_irqsave are open coded to work with compact_control.
Also add a debug func in locking which may give some clues if there are
sth out of hands.

Daniel Jordan's testing show 62% improvement on modified readtwice case on
his 2P * 10 core * 2 HT broadwell box.
https://lore.kernel.org/lkml/20200915165807.kpp7uhiw7l3loofu@ca-dmjordan1.us.oracle.com/

Hugh Dickins helped on the patch polish, thanks!

[alex.shi@linux.alibaba.com: fix comment typo]
  Link: https://lkml.kernel.org/r/5b085715-292a-4b43-50b3-d73dc90d1de5@linux.alibaba.com
[alex.shi@linux.alibaba.com: use page_memcg()]
  Link: https://lkml.kernel.org/r/5a4c2b72-7ee8-2478-fc0e-85eb83aafec4@linux.alibaba.com

Link: https://lkml.kernel.org/r/1604566549-62481-18-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi 
Acked-by: Hugh Dickins 
Acked-by: Johannes Weiner 
Cc: Rong Chen 
Cc: Michal Hocko 
Cc: Vladimir Davydov 
Cc: Yang Shi 
Cc: Matthew Wilcox 
Cc: Konstantin Khlebnikov 
Cc: Daniel Jordan 
Cc: Alexander Duyck 
Cc: Andrea Arcangeli 
Cc: Andrey Ryabinin 
Cc: "Huang, Ying" 
Cc: Jann Horn 
Cc: Joonsoo Kim 
Cc: Kirill A. Shutemov 
Cc: Kirill A. Shutemov 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Mika Penttilä 
Cc: Minchan Kim 
Cc: Shakeel Butt 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/memcg: add debug checking in lock_page_memcg

2020-12-15T22:48:03+00:00

Add a debug checking in lock_page_memcg, then we could get alarm if
anything wrong here.

Link: https://lkml.kernel.org/r/1604566549-62481-9-git-send-email-alex.shi@linux.alibaba.com
Suggested-by: Johannes Weiner 
Signed-off-by: Alex Shi 
Acked-by: Hugh Dickins 
Acked-by: Johannes Weiner 
Cc: Michal Hocko 
Cc: Vladimir Davydov 
Cc: Alexander Duyck 
Cc: Andrea Arcangeli 
Cc: Andrey Ryabinin 
Cc: "Chen, Rong A" 
Cc: Daniel Jordan 
Cc: "Huang, Ying" 
Cc: Jann Horn 
Cc: Joonsoo Kim 
Cc: Kirill A. Shutemov 
Cc: Kirill A. Shutemov 
Cc: Konstantin Khlebnikov 
Cc: Matthew Wilcox (Oracle) 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Mika Penttilä 
Cc: Minchan Kim 
Cc: Shakeel Butt 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Cc: Yang Shi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'net-next-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

2020-12-15T21:22:29+00:00

Pull networking updates from Jakub Kicinski:
 "Core:

   - support "prefer busy polling" NAPI operation mode, where we defer
     softirq for some time expecting applications to periodically busy
     poll

   - AF_XDP: improve efficiency by more batching and hindering the
     adjacency cache prefetcher

   - af_packet: make packet_fanout.arr size configurable up to 64K

   - tcp: optimize TCP zero copy receive in presence of partial or
     unaligned reads making zero copy a performance win for much smaller
     messages

   - XDP: add bulk APIs for returning / freeing frames

   - sched: support fragmenting IP packets as they come out of conntrack

   - net: allow virtual netdevs to forward UDP L4 and fraglist GSO skbs

  BPF:

   - BPF switch from crude rlimit-based to memcg-based memory accounting

   - BPF type format information for kernel modules and related tracing
     enhancements

   - BPF implement task local storage for BPF LSM

   - allow the FENTRY/FEXIT/RAW_TP tracing programs to use
     bpf_sk_storage

  Protocols:

   - mptcp: improve multiple xmit streams support, memory accounting and
     many smaller improvements

   - TLS: support CHACHA20-POLY1305 cipher

   - seg6: add support for SRv6 End.DT4/DT6 behavior

   - sctp: Implement RFC 6951: UDP Encapsulation of SCTP

   - ppp_generic: add ability to bridge channels directly

   - bridge: Connectivity Fault Management (CFM) support as is defined
     in IEEE 802.1Q section 12.14.

  Drivers:

   - mlx5: make use of the new auxiliary bus to organize the driver
     internals

   - mlx5: more accurate port TX timestamping support

   - mlxsw:
      - improve the efficiency of offloaded next hop updates by using
        the new nexthop object API
      - support blackhole nexthops
      - support IEEE 802.1ad (Q-in-Q) bridging

   - rtw88: major bluetooth co-existance improvements

   - iwlwifi: support new 6 GHz frequency band

   - ath11k: Fast Initial Link Setup (FILS)

   - mt7915: dual band concurrent (DBDC) support

   - net: ipa: add basic support for IPA v4.5

  Refactor:

   - a few pieces of in_interrupt() cleanup work from Sebastian Andrzej
     Siewior

   - phy: add support for shared interrupts; get rid of multiple driver
     APIs and have the drivers write a full IRQ handler, slight growth
     of driver code should be compensated by the simpler API which also
     allows shared IRQs

   - add common code for handling netdev per-cpu counters

   - move TX packet re-allocation from Ethernet switch tag drivers to a
     central place

   - improve efficiency and rename nla_strlcpy

   - number of W=1 warning cleanups as we now catch those in a patchwork
     build bot

  Old code removal:

   - wan: delete the DLCI / SDLA drivers

   - wimax: move to staging

   - wifi: remove old WDS wifi bridging support"

* tag 'net-next-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1922 commits)
  net: hns3: fix expression that is currently always true
  net: fix proc_fs init handling in af_packet and tls
  nfc: pn533: convert comma to semicolon
  af_vsock: Assign the vsock transport considering the vsock address flags
  af_vsock: Set VMADDR_FLAG_TO_HOST flag on the receive path
  vsock_addr: Check for supported flag values
  vm_sockets: Add VMADDR_FLAG_TO_HOST vsock flag
  vm_sockets: Add flags field in the vsock address data structure
  net: Disable NETIF_F_HW_TLS_TX when HW_CSUM is disabled
  tcp: Add logic to check for SYN w/ data in tcp_simple_retransmit
  net: mscc: ocelot: install MAC addresses in .ndo_set_rx_mode from process context
  nfc: s3fwrn5: Release the nfc firmware
  net: vxget: clean up sparse warnings
  mlxsw: spectrum_router: Use eXtended mezzanine to offload IPv4 router
  mlxsw: spectrum: Set KVH XLT cache mode for Spectrum2/3
  mlxsw: spectrum_router_xm: Introduce basic XM cache flushing
  mlxsw: reg: Add Router LPM Cache Enable Register
  mlxsw: reg: Add Router LPM Cache ML Delete Register
  mlxsw: spectrum_router_xm: Implement L-value tracking for M-index
  mlxsw: reg: Add XM Router M Table Register
  ...

mm: memcontrol: account pagetables per node

2020-12-15T20:13:40+00:00

For many workloads, pagetable consumption is significant and it makes
sense to expose it in the memory.stat for the memory cgroups.  However at
the moment, the pagetables are accounted per-zone.  Converting them to
per-node and using the right interface will correctly account for the
memory cgroups as well.

[akpm@linux-foundation.org: export __mod_lruvec_page_state to modules for arch/mips/kvm/]

Link: https://lkml.kernel.org/r/20201130212541.2781790-3-shakeelb@google.com
Signed-off-by: Shakeel Butt 
Acked-by: Johannes Weiner 
Acked-by: Roman Gushchin 
Cc: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds