Pull pci fixes from Bjorn Helgaas:

 - Limit Max_Read_Request_Size (MRRS) on some MIPS Loongson systems
   because they don't all support MRRS > 256, and firmware doesn't
   always initialize it correctly, which meant some PCIe devices didn't
   work (Jiaxun Yang)

 - Add and use pci_enable_link_state_locked() to prevent potential
   deadlocks in vmd and qcom drivers (Johan Hovold)

 - Revert recent (v6.5) acpiphp resource assignment changes that fixed
   issues with hot-adding devices on a root bus or with large BARs, but
   introduced new issues with GPU initialization and hot-adding SCSI
   disks in QEMU VMs and (Bjorn Helgaas)

* tag 'pci-v6.7-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci:
  Revert "PCI: acpiphp: Reassign resources on bridge if necessary"
  PCI/ASPM: Add pci_disable_link_state_locked() lockdep assert
  PCI/ASPM: Clean up __pci_disable_link_state() 'sem' parameter
  PCI: qcom: Clean up ASPM comment
  PCI: qcom: Fix potential deadlock when enabling ASPM
  PCI: vmd: Fix potential deadlock when enabling ASPM
  PCI/ASPM: Add pci_enable_link_state_locked()
  PCI: loongson: Limit MRRS to 256

This code is rarely (never?) enabled by distros, and it hasn't caught
anything in decades. Let's kill off this legacy debug code.

Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There are multiple ways to grab references to credentials, and the only
protection we have against overflowing it is the memory required to do
so.

With memory sizes only moving in one direction, let's bump the reference
count to 64-bit and move it outside the realm of feasibly overflowing.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull io_uring fixes from Jens Axboe:
 "Just two minor fixes:

   - Fix for the io_uring socket option commands using the wrong value
     on some archs (Al)

   - Tweak to the poll lazy wake enable (me)"

* tag 'io_uring-6.7-2023-12-15' of git://git.kernel.dk/linux:
  io_uring/cmd: fix breakage in SOCKET_URING_OP_SIOC* implementation
  io_uring/poll: don't enable lazy wake for POLLEXCLUSIVE

Pull misc fixes from Andrew Morton:
 "17 hotfixes. 8 are cc:stable and the other 9 pertain to post-6.6
  issues"

* tag 'mm-hotfixes-stable-2023-12-15-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm/mglru: reclaim offlined memcgs harder
  mm/mglru: respect min_ttl_ms with memcgs
  mm/mglru: try to stop at high watermarks
  mm/mglru: fix underprotected page cache
  mm/shmem: fix race in shmem_undo_range w/THP
  Revert "selftests: error out if kernel header files are not yet built"
  crash_core: fix the check for whether crashkernel is from high memory
  x86, kexec: fix the wrong ifdeffery CONFIG_KEXEC
  sh, kexec: fix the incorrect ifdeffery and dependency of CONFIG_KEXEC
  mips, kexec: fix the incorrect ifdeffery and dependency of CONFIG_KEXEC
  m68k, kexec: fix the incorrect ifdeffery and build dependency of CONFIG_KEXEC
  loongarch, kexec: change dependency of object files
  mm/damon/core: make damon_start() waits until kdamond_fn() starts
  selftests/mm: cow: print ksft header before printing anything else
  mm: fix VMA heap bounds checking
  riscv: fix VMALLOC_START definition
  kexec: drop dependency on ARCH_SUPPORTS_KEXEC from CRASH_DUMP

Pull networking fixes from Paolo Abeni:
"Current release - regressions:

   - tcp: fix tcp_disordered_ack() vs usec TS resolution

  Current release - new code bugs:

   - dpll: sanitize possible null pointer dereference in
     dpll_pin_parent_pin_set()

   - eth: octeon_ep: initialise control mbox tasks before using APIs

  Previous releases - regressions:

   - io_uring/af_unix: disable sending io_uring over sockets

   - eth: mlx5e:
       - TC, don't offload post action rule if not supported
       - fix possible deadlock on mlx5e_tx_timeout_work

   - eth: iavf: fix iavf_shutdown to call iavf_remove instead iavf_close

   - eth: bnxt_en: fix skb recycling logic in bnxt_deliver_skb()

   - eth: ena: fix DMA syncing in XDP path when SWIOTLB is on

   - eth: team: fix use-after-free when an option instance allocation
     fails

  Previous releases - always broken:

   - neighbour: don't let neigh_forced_gc() disable preemption for long

   - net: prevent mss overflow in skb_segment()

   - ipv6: support reporting otherwise unknown prefix flags in
     RTM_NEWPREFIX

   - tcp: remove acked SYN flag from packet in the transmit queue
     correctly

   - eth: octeontx2-af:
       - fix a use-after-free in rvu_nix_register_reporters
       - fix promisc mcam entry action

   - eth: dwmac-loongson: make sure MDIO is initialized before use

   - eth: atlantic: fix double free in ring reinit logic"

* tag 'net-6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (62 commits)
  net: atlantic: fix double free in ring reinit logic
  appletalk: Fix Use-After-Free in atalk_ioctl
  net: stmmac: Handle disabled MDIO busses from devicetree
  net: stmmac: dwmac-qcom-ethqos: Fix drops in 10M SGMII RX
  dpaa2-switch: do not ask for MDB, VLAN and FDB replay
  dpaa2-switch: fix size of the dma_unmap
  net: prevent mss overflow in skb_segment()
  vsock/virtio: Fix unsigned integer wrap around in virtio_transport_has_space()
  Revert "tcp: disable tcp_autocorking for socket when TCP_NODELAY flag is set"
  MIPS: dts: loongson: drop incorrect dwmac fallback compatible
  stmmac: dwmac-loongson: drop useless check for compatible fallback
  stmmac: dwmac-loongson: Make sure MDIO is initialized before use
  tcp: disable tcp_autocorking for socket when TCP_NODELAY flag is set
  dpll: sanitize possible null pointer dereference in dpll_pin_parent_pin_set()
  net: ena: Fix XDP redirection error
  net: ena: Fix DMA syncing in XDP path when SWIOTLB is on
  net: ena: Fix xdp drops handling due to multibuf packets
  net: ena: Destroy correct number of xdp queues upon failure
  net: Remove acked SYN flag from packet in the transmit queue correctly
  qed: Fix a potential use-after-free in qed_cxt_tables_alloc
  ...

There are a few quirks around using lazy wake for poll unconditionally,
and one of them is related the EPOLLEXCLUSIVE. Those may trigger
exclusive wakeups, which wake a limited number of entries in the wait
queue. If that wake number is less than the number of entries someone is
waiting for (and that someone is also using DEFER_TASKRUN), then we can
get stuck waiting for more entries while we should be processing the ones
we already got.

If we're doing exclusive poll waits, flag the request as not being
compatible with lazy wakeups.

Reported-by: Pavel Begunkov <asml.silence@gmail.com>
Fixes: 6ce4a93dbb5b ("io_uring/poll: use IOU_F_TWQ_LAZY_WAKE for wakeups")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

In the effort to reduce zombie memcgs [1], it was discovered that the
memcg LRU doesn't apply enough pressure on offlined memcgs.  Specifically,
instead of rotating them to the tail of the current generation
(MEMCG_LRU_TAIL) for a second attempt, it moves them to the next
generation (MEMCG_LRU_YOUNG) after the first attempt.

Not applying enough pressure on offlined memcgs can cause them to build
up, and this can be particularly harmful to memory-constrained systems.

On Pixel 8 Pro, launching apps for 50 cycles:
                 Before  After  Change
  Zombie memcgs  45      35     -22%

[1] https://lore.kernel.org/CABdmKX2M6koq4Q0Cmp_-=wbP0Qa190HdEGGaHfxNS05gAkUtPA@mail.gmail.com/

Link: https://lkml.kernel.org/r/20231208061407.2125867-4-yuzhao@google.com
Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists")
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reported-by: T.J. Mercier <tjmercier@google.com>
Tested-by: T.J. Mercier <tjmercier@google.com>
Cc: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

While investigating kswapd "consuming 100% CPU" [1] (also see "mm/mglru:
try to stop at high watermarks"), it was discovered that the memcg LRU can
breach the thrashing protection imposed by min_ttl_ms.

Before the memcg LRU:
  kswapd()
    shrink_node_memcgs()
      mem_cgroup_iter()
        inc_max_seq()  // always hit a different memcg
    lru_gen_age_node()
      mem_cgroup_iter()
        check the timestamp of the oldest generation

After the memcg LRU:
  kswapd()
    shrink_many()
      restart:
        iterate the memcg LRU:
          inc_max_seq()  // occasionally hit the same memcg
          if raced with lru_gen_rotate_memcg():
            goto restart
    lru_gen_age_node()
      mem_cgroup_iter()
        check the timestamp of the oldest generation

Specifically, when the restart happens in shrink_many(), it needs to stick
with the (memcg LRU) generation it began with.  In other words, it should
neither re-read memcg_lru->seq nor age an lruvec of a different
generation.  Otherwise it can hit the same memcg multiple times without
giving lru_gen_age_node() a chance to check the timestamp of that memcg's
oldest generation (against min_ttl_ms).

[1] https://lore.kernel.org/CAK8fFZ4DY+GtBA40Pm7Nn5xCHy+51w3sfxPqkqpqakSXYyX+Wg@mail.gmail.com/

Link: https://lkml.kernel.org/r/20231208061407.2125867-3-yuzhao@google.com
Fixes: e4dde56cd208 ("mm: multi-gen LRU: per-node lru_gen_folio lists")
Signed-off-by: Yu Zhao <yuzhao@google.com>
Tested-by: T.J. Mercier <tjmercier@google.com>
Cc: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Unmapped folios accessed through file descriptors can be underprotected. 
Those folios are added to the oldest generation based on:

1. The fact that they are less costly to reclaim (no need to walk the
   rmap and flush the TLB) and have less impact on performance (don't
   cause major PFs and can be non-blocking if needed again).
2. The observation that they are likely to be single-use. E.g., for
   client use cases like Android, its apps parse configuration files
   and store the data in heap (anon); for server use cases like MySQL,
   it reads from InnoDB files and holds the cached data for tables in
   buffer pools (anon).

However, the oldest generation can be very short lived, and if so, it
doesn't provide the PID controller with enough time to respond to a surge
of refaults.  (Note that the PID controller uses weighted refaults and
those from evicted generations only take a half of the whole weight.) In
other words, for a short lived generation, the moving average smooths out
the spike quickly.

To fix the problem:
1. For folios that are already on LRU, if they can be beyond the
   tracking range of tiers, i.e., five accesses through file
   descriptors, move them to the second oldest generation to give them
   more time to age. (Note that tiers are used by the PID controller
   to statistically determine whether folios accessed multiple times
   through file descriptors are worth protecting.)
2. When adding unmapped folios to LRU, adjust the placement of them so
   that they are not too close to the tail. The effect of this is
   similar to the above.

On Android, launching 55 apps sequentially:
                           Before     After      Change
  workingset_refault_anon  25641024   25598972   0%
  workingset_refault_file  115016834  106178438  -8%

Link: https://lkml.kernel.org/r/20231208061407.2125867-1-yuzhao@google.com
Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation")
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reported-by: Charan Teja Kalla <quic_charante@quicinc.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jaroslav Pulchart <jaroslav.pulchart@gooddata.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>