Now that a client can have multiple xprts, we need to add
them all to debugs.
The first one is still "xprt"
Subsequent xprts are "xprt1", "xprt2", etc.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Now that a client can have multiple xprts, we need to
report the statistics for all of them.
Reported-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

With NFSv4.1, different network connections need to be explicitly
bound to a session.  During session startup, this is not possible
so only a single connection must be used for session startup.

So add a task flag to disable the default round-robin choice of
connections (when nconnect > 1) and force the use of a single
connection.
Then use that flag on all requests for session management - for
consistence, include NFSv4.0 management (SETCLIENTID) and session
destruction
Reported-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

If the user specifies -onconnect=<number> mount option, and the transport
protocol is TCP, then set up <number> connections to the pNFS data server
as well. The connections will all go to the same IP address.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

If the user specifies the -onconn=<number> mount option, and the transport
protocol is TCP, then set up <number> connections to the server. The
connections will all go to the same IP address.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

Allow the user to specify that the client should use multiple connections
to the server. For the moment, this functionality will be limited to
TCP and to NFSv4.x (x>0).
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

Add an argument to struct rpc_create_args that allows the specification
of how many transport connections you want to set up to the server.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

For now, just count the queue length. It is less accurate than counting
number of bytes queued, but easier to implement.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

According to the open() manpage, Linux reserves the access mode 3
to mean "check for read and write permission on the file and return
a file descriptor that can't be used for reading or writing."

Currently, the NFSv4 code will ask the server to open the file,
and will use an incorrect share access mode of 0. Since it has
an incorrect share access mode, the client later forgets to send
a corresponding close, meaning it can leak stateids on the server.

Fixes: ce4ef7c0 ("NFS: Split out NFS v4 file operations")
Cc: stable@vger.kernel.org # 3.6+
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

When mapping the NFSv4 context to an open mode and access mode,
we need to treat the FMODE_EXEC flag differently. For the open
mode, FMODE_EXEC means we need read share access. For the access
mode checking, we need to verify that the user actually has
execute access.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Pull MIPS fixes from Paul Burton:
 "A few more MIPS fixes:

   - Fix a silly typo in virt_addr_valid which led to completely bogus
     behavior (that happened to stop tripping up hardened usercopy
     despite being broken).

   - Fix UART parity setup on AR933x systems.

   - A build fix for non-Linux build machines.

   - Have the 'all' make target build DTBs, primarily to fit in with the
     behavior of scripts/package/builddeb.

   - Handle an execution hazard in TLB exceptions that use KScratch
     registers, which could inadvertently clobber the $1 register on
     some generally higher-end out-of-order CPUs.

   - A MAINTAINERS update to fix the path to the NAND driver for Ingenic
     systems"

* tag 'mips_fixes_5.2_2' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
  MAINTAINERS: Correct path to moved files
  MIPS: Add missing EHB in mtc0 -> mfc0 sequence.
  MIPS: have "plain" make calls build dtbs for selected platforms
  MIPS: fix build on non-linux hosts
  MIPS: ath79: fix ar933x uart parity mode
  MIPS: Fix bounds check virt_addr_valid

Pull dmaengine fixes from Vinod Koul:

 - bam_dma fix for completed descriptor count

 - fix for imx-sdma remove BD_INTR for channel0 and use-after-free on
   probe error path

 - endian bug fix in jz4780 IRQ handler

* tag 'dmaengine-fix-5.2' of git://git.infradead.org/users/vkoul/slave-dma:
  dmaengine: qcom: bam_dma: Fix completed descriptors count
  dmaengine: imx-sdma: remove BD_INTR for channel0
  dmaengine: imx-sdma: fix use-after-free on probe error path
  dmaengine: jz4780: Fix an endian bug in IRQ handler

Pull SCSI fixes from James Bottomley:
 "Two iscsi fixes.

  One for an oops in the client which can be triggered by the server
  authentication protocol and the other in the target code which causes
  data corruption"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: iscsi: set auth_protocol back to NULL if CHAP_A value is not supported
  scsi: target/iblock: Fix overrun in WRITE SAME emulation

Pull vfs fixlet from Al Viro:
 "Fix bogus default y in Kconfig (VALIDATE_FS_PARSER)

  That thing should not be turned on by default, especially since it's
  not quiet in case it finds no problems. Geert has sent the obvious fix
  quite a few times, but it fell through the cracks"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: VALIDATE_FS_PARSER should default to n

This reverts commit 5fd4ca2d.

Mikhail Gavrilov reports that it causes the VM_BUG_ON_PAGE() in
__delete_from_swap_cache() to trigger:

   page:ffffd6d34dff0000 refcount:1 mapcount:1 mapping:ffff97812323a689 index:0xfecec363
   anon
   flags: 0x17fffe00080034(uptodate|lru|active|swapbacked)
   raw: 0017fffe00080034 ffffd6d34c67c508 ffffd6d3504b8d48 ffff97812323a689
   raw: 00000000fecec363 0000000000000000 0000000100000000 ffff978433ace000
   page dumped because: VM_BUG_ON_PAGE(entry != page)
   page->mem_cgroup:ffff978433ace000
   ------------[ cut here ]------------
   kernel BUG at mm/swap_state.c:170!
   invalid opcode: 0000 [#1] SMP NOPTI
   CPU: 1 PID: 221 Comm: kswapd0 Not tainted 5.2.0-0.rc2.git0.1.fc31.x86_64 #1
   Hardware name: System manufacturer System Product Name/ROG STRIX X470-I GAMING, BIOS 2202 04/11/2019
   RIP: 0010:__delete_from_swap_cache+0x20d/0x240
   Code: 30 65 48 33 04 25 28 00 00 00 75 4a 48 83 c4 38 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 c7 c6 2f dc 0f 8a 48 89 c7 e8 93 1b fd ff <0f> 0b 48 c7 c6 a8 74 0f 8a e8 85 1b fd ff 0f 0b 48 c7 c6 a8 7d 0f
   RSP: 0018:ffffa982036e7980 EFLAGS: 00010046
   RAX: 0000000000000021 RBX: 0000000000000040 RCX: 0000000000000006
   RDX: 0000000000000000 RSI: 0000000000000086 RDI: ffff97843d657900
   RBP: 0000000000000001 R08: ffffa982036e7835 R09: 0000000000000535
   R10: ffff97845e21a46c R11: ffffa982036e7835 R12: ffff978426387120
   R13: 0000000000000000 R14: ffffd6d34dff0040 R15: ffffd6d34dff0000
   FS:  0000000000000000(0000) GS:ffff97843d640000(0000) knlGS:0000000000000000
   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
   CR2: 00002cba88ef5000 CR3: 000000078a97c000 CR4: 00000000003406e0
   Call Trace:
    delete_from_swap_cache+0x46/0xa0
    try_to_free_swap+0xbc/0x110
    swap_writepage+0x13/0x70
    pageout.isra.0+0x13c/0x350
    shrink_page_list+0xc14/0xdf0
    shrink_inactive_list+0x1e5/0x3c0
    shrink_node_memcg+0x202/0x760
    shrink_node+0xe0/0x470
    balance_pgdat+0x2d1/0x510
    kswapd+0x220/0x420
    kthread+0xfb/0x130
    ret_from_fork+0x22/0x40

and it's not immediately obvious why it happens.  It's too late in the
rc cycle to do anything but revert for now.

Link: https://lore.kernel.org/lkml/CABXGCsN9mYmBD-4GaaeW_NrDu+FDXLzr_6x+XNxfmFV6QkYCDg@mail.gmail.com/Reported-and-bisected-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Suggested-by: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Kirill Shutemov <kirill@shutemov.name>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull kvm fixes from Paolo Bonzini:
 "x86 bugfix patches and one compilation fix for ARM"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: arm64/sve: Fix vq_present() macro to yield a bool
  KVM: LAPIC: Fix pending interrupt in IRR blocked by software disable LAPIC
  KVM: nVMX: Change KVM_STATE_NESTED_EVMCS to signal vmcs12 is copied from eVMCS
  KVM: nVMX: Allow restore nested-state to enable eVMCS when vCPU in SMM
  KVM: x86: degrade WARN to pr_warn_ratelimited

Pull mtf fixes from Miquel Raynal:

 - Fix the memory organization structure of a Macronix SPI-NAND chip.

 - Fix a build dependency wrongly described.

 - Fix the sunxi NAND driver for A23/A33 SoCs by (a) reverting the
   faulty commit introducing broken DMA support and (b) applying another
   commit bringing working DMA support.

* tag 'mtd/fixes-for-5.2-final' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux:
  mtd: rawnand: sunxi: Add A23/A33 DMA support with extra MBUS configuration
  Revert "mtd: rawnand: sunxi: Add A23/A33 DMA support"
  mtd: rawnand: ingenic: Fix ingenic_ecc dependency
  mtd: spinand: Fix max_bad_eraseblocks_per_lun info in memorg

Pull i2c fixlet from Wolfram Sang:
 "I2C has a MAINTAINERS update which will be benfitial for developers,
  so let's add it right away"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: tegra: Add Dmitry as a reviewer

Pull nfsd fixes from Bruce Fields:
 "Two more quick bugfixes for nfsd: fixing a regression causing mount
  failures on high-memory machines and fixing the DRC over RDMA"

* tag 'nfsd-5.2-2' of git://linux-nfs.org/~bfields/linux:
  nfsd: Fix overflow causing non-working mounts on 1 TB machines
  svcrdma: Ignore source port when computing DRC hash

Allwinner NAND controllers can make use of DMA to enhance the I/O
throughput thanks to ECC pipelining. DMA handling with A23/A33 NAND IP
is a bit different than with the older SoCs, hence the introduction of
a new compatible to handle:
* the differences between register offsets,
* the burst length change from 4 to minimum 8,
* manage SRAM accesses through MBUS with extra configuration.

Fixes: c49836f0 ("mtd: rawnand: sunxi: Add A23/A33 DMA support")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

This reverts commit c49836f0.

The commit is wrong and its approach actually does not work. Let's
revert it in order to add the feature with a clean patch.

Fixes: c49836f0 ("mtd: rawnand: sunxi: Add A23/A33 DMA support")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

I'm contributing to Tegra's upstream development in general and happened
to review the Tegra's I2C patches for awhile because I'm actively using
upstream kernel on all of my Tegra-powered devices and initially some of
the submitted patches were getting my attention since they were causing
problems. Recently Wolfram Sang asked whether I'm interested in becoming
a reviewer for the driver and I don't mind at all.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
[wsa: ack was expressed by Thierry Reding in a mail thread]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

CONFIG_VALIDATE_FS_PARSER is a debugging tool to check that the parser
tables are vaguely sane.  It was set to default to 'Y' for the moment to
catch errors in upcoming fs conversion development.

Make sure it is not enabled by default in the final release of v5.1.

Fixes: 31d921c7 ("vfs: Add configuration parser helpers")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

The original implementation of vq_present() relied on aggressive
inlining in order for the compiler to know that the code is
correct, due to some const-casting issues.  This was causing sparse
and clang to complain, while GCC compiled cleanly.

Commit 0c529ff7 addressed this problem, but since vq_present()
is no longer a function, there is now no implicit casting of the
returned value to the return type (bool).

In set_sve_vls(), this uncast bit value is compared against a bool,
and so may spuriously compare as unequal when both are nonzero.  As
a result, KVM may reject valid SVE vector length configurations as
invalid, and vice versa.

Fix it by forcing the returned value to a bool.
Signed-off-by: Zhang Lei <zhang.lei@jp.fujitsu.com>
Fixes: 0c529ff7 ("KVM: arm64: Implement vq_present() as a macro")
Signed-off-by: Dave Martin <Dave.Martin@arm.com> [commit message rewrite]
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

One space is left unused in circular FIFO to differentiate
'full' and 'empty' cases. So take that in to account while
counting for the descriptors completed.

Fixes the issue reported here,
	https://lkml.org/lkml/2019/6/18/669

Cc: stable@vger.kernel.org
Reported-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

It is possible for an irq triggered by channel0 to be received later
after clks are disabled once firmware loaded during sdma probe. If
that happens then clearing them by writing to SDMA_H_INTR won't work
and the kernel will hang processing infinite interrupts. Actually,
don't need interrupt triggered on channel0 since it's pollling
SDMA_H_STATSTOP to know channel0 done rather than interrupt in
current code, just clear BD_INTR to disable channel0 interrupt to
avoid the above case.
This issue was brought by commit 1d069bfa ("dmaengine: imx-sdma:
ack channel 0 IRQ in the interrupt handler") which didn't take care
the above case.

Fixes: 1d069bfa ("dmaengine: imx-sdma: ack channel 0 IRQ in the interrupt handler")
Cc: stable@vger.kernel.org #5.0+
Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Reported-by: Sven Van Asbroeck <thesven73@gmail.com>
Tested-by: Sven Van Asbroeck <thesven73@gmail.com>
Reviewed-by: Michael Olbrich <m.olbrich@pengutronix.de>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

If probe() fails anywhere beyond the point where
sdma_get_firmware() is called, then a kernel oops may occur.

Problematic sequence of events:
1. probe() calls sdma_get_firmware(), which schedules the
   firmware callback to run when firmware becomes available,
   using the sdma instance structure as the context
2. probe() encounters an error, which deallocates the
   sdma instance structure
3. firmware becomes available, firmware callback is
   called with deallocated sdma instance structure
4. use after free - kernel oops !

Solution: only attempt to load firmware when we're certain
that probe() will succeed. This guarantees that the firmware
callback's context will remain valid.

Note that the remove() path is unaffected by this issue: the
firmware loader will increment the driver module's use count,
ensuring that the module cannot be unloaded while the
firmware callback is pending or running.
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Reviewed-by: Robin Gong <yibin.gong@nxp.com>
[vkoul: fixed braces for if condition]
Signed-off-by: Vinod Koul <vkoul@kernel.org>

The "pending" variable was a u32 but we cast it to an unsigned long
pointer when we do the for_each_set_bit() loop.  The problem is that on
big endian 64bit systems that results in an out of bounds read.

Fixes: 4e4106f5 ("dmaengine: jz4780: Fix transfers being ACKed too soon")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Pull drm fixes from Dave Airlie:
 "I skipped last week because there wasn't much worth doing, this week
  got a few more fixes in.

  amdgpu:
   - default register value change
   - runpm regression fix
   - fan control fix

  i915:
   - fix Ironlake regression

  panfrost:
   - fix a double free

  virtio:
   - fix a locking bug

  imx:
   - crtc disable fixes"

* tag 'drm-fixes-2019-07-05-1' of git://anongit.freedesktop.org/drm/drm:
  drm/imx: only send event on crtc disable if kept disabled
  drm/imx: notify drm core before sending event during crtc disable
  drm/i915/ringbuffer: EMIT_INVALIDATE *before* switch context
  drm/amdgpu/gfx9: use reset default for PA_SC_FIFO_SIZE
  drm/amdgpu: Don't skip display settings in hwmgr_resume()
  drm/amd/powerplay: use hardware fan control if no powerplay fan table
  drm/panfrost: Fix a double-free error
  drm/etnaviv: add missing failure path to destroy suballoc
  drm/virtio: move drm_connector_update_edid_property() call

drm/imx: fix stale vblank timestamp after a modeset

This series fixes stale vblank timestamps in the first event sent after
a crtc was disabled. The core now is notified via drm_crtc_vblank_off
before sending the last pending event in atomic_disable. If the crtc is
reenabled right away during to a modeset, the event is not sent at all,
as the next vblank will take care of it.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/1562237119.6641.16.camel@pengutronix.de

Pull crypto fixes from Herbert Xu:
 "This fixes two memory leaks and a list corruption bug"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: user - prevent operating on larval algorithms
  crypto: cryptd - Fix skcipher instance memory leak
  lib/mpi: Fix karactx leak in mpi_powm

Merge more fixes from Andrew Morton:
 "5 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  swap_readpage(): avoid blk_wake_io_task() if !synchronous
  devres: allow const resource arguments
  mm/vmscan.c: prevent useless kswapd loops
  fs/userfaultfd.c: disable irqs for fault_pending and event locks
  mm/page_alloc.c: fix regression with deferred struct page init

Pull ARM SoC fixes from Olof Johansson:
 "Likely our final small batch of fixes for 5.2:

   - Some fixes for USB on davinci, regressions were due to the recent
     conversion of the OCHI driver to use GPIO regulators

   - A fixup of kconfig dependencies for a TI irq controller

   - A switch of armada-38x to avoid dropped characters on uart, caused
     by switch of base inherited platform description earlier this year"

* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
  ARM: davinci: da830-evm: fix GPIO lookup for OHCI
  ARM: davinci: omapl138-hawk: add missing regulator constraints for OHCI
  ARM: davinci: da830-evm: add missing regulator constraints for OHCI
  soc: ti: fix irq-ti-sci link error
  ARM: dts: armada-xp-98dx3236: Switch to armada-38x-uart serial node

Pull dax fix from Dan Williams:
 "A single dax fix that has been soaking awaiting other fixes under
  discussion to join it. As it is getting late in the cycle lets proceed
  with this fix and save follow-on changes for post-v5.3-rc1.

   - Fix xarray entry association for mixed mappings"

* tag 'dax-fix-5.2-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: Fix xarray entry association for mixed mappings

Pull do_move_mount() fix from Al Viro:
 "Regression fix"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  vfs: move_mount: reject moving kernel internal mounts

swap_readpage() sets waiter = bio->bi_private even if synchronous = F,
this means that the caller can get the spurious wakeup after return.

This can be fatal if blk_wake_io_task() does
set_current_state(TASK_RUNNING) after the caller does
set_special_state(), in the worst case the kernel can crash in
do_task_dead().

Link: http://lkml.kernel.org/r/20190704160301.GA5956@redhat.com
Fixes: 0619317f ("block: add polled wakeup task helper")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Qian Cai <cai@lca.pw>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devm_ioremap_resource() does not currently take 'const' arguments, which
results in a warning from the first driver trying to do it anyway:

  drivers/gpio/gpio-amd-fch.c: In function 'amd_fch_gpio_probe':
  drivers/gpio/gpio-amd-fch.c:171:49: error: passing argument 2 of 'devm_ioremap_resource' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
    priv->base = devm_ioremap_resource(&pdev->dev, &amd_fch_gpio_iores);
                                                   ^~~~~~~~~~~~~~~~~~~

Change the prototype to allow it, as there is no real reason not to.

Link: http://lkml.kernel.org/r/20190628150049.1108048-1-arnd@arndb.de
Fixes: 9bb2e0452508 ("gpio: amd: Make resource struct const")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In production we have noticed hard lockups on large machines running
large jobs due to kswaps hoarding lru lock within isolate_lru_pages when
sc->reclaim_idx is 0 which is a small zone.  The lru was couple hundred
GiBs and the condition (page_zonenum(page) > sc->reclaim_idx) in
isolate_lru_pages() was basically skipping GiBs of pages while holding
the LRU spinlock with interrupt disabled.

On further inspection, it seems like there are two issues:

(1) If kswapd on the return from balance_pgdat() could not sleep (i.e.
    node is still unbalanced), the classzone_idx is unintentionally set
    to 0 and the whole reclaim cycle of kswapd will try to reclaim only
    the lowest and smallest zone while traversing the whole memory.

(2) Fundamentally isolate_lru_pages() is really bad when the
    allocation has woken kswapd for a smaller zone on a very large machine
    running very large jobs.  It can hoard the LRU spinlock while skipping
    over 100s of GiBs of pages.

This patch only fixes (1).  (2) needs a more fundamental solution.  To
fix (1), in the kswapd context, if pgdat->kswapd_classzone_idx is
invalid use the classzone_idx of the previous kswapd loop otherwise use
the one the waker has requested.

Link: http://lkml.kernel.org/r/20190701201847.251028-1-shakeelb@google.com
Fixes: e716f2eb ("mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>