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Baoquan He 98b57685c2 mm: memmap defer init doesn't work as expected 
commit dc2da7b45ffe954a0090f5d0310ed7b0b37d2bd2 upstream.

VMware observed a performance regression during memmap init on their
platform, and bisected to commit 73a6e474cb ("mm: memmap_init:
iterate over memblock regions rather that check each PFN") causing it.

Before the commit:

  [0.033176] Normal zone: 1445888 pages used for memmap
  [0.033176] Normal zone: 89391104 pages, LIFO batch:63
  [0.035851] ACPI: PM-Timer IO Port: 0x448

With commit

  [0.026874] Normal zone: 1445888 pages used for memmap
  [0.026875] Normal zone: 89391104 pages, LIFO batch:63
  [2.028450] ACPI: PM-Timer IO Port: 0x448

The root cause is the current memmap defer init doesn't work as expected.

Before, memmap_init_zone() was used to do memmap init of one whole zone,
to initialize all low zones of one numa node, but defer memmap init of
the last zone in that numa node.  However, since commit 73a6e474cb,
function memmap_init() is adapted to iterater over memblock regions
inside one zone, then call memmap_init_zone() to do memmap init for each
region.

E.g, on VMware's system, the memory layout is as below, there are two
memory regions in node 2.  The current code will mistakenly initialize the
whole 1st region [mem 0xab00000000-0xfcffffffff], then do memmap defer to
iniatialize only one memmory section on the 2nd region [mem
0x10000000000-0x1033fffffff].  In fact, we only expect to see that there's
only one memory section's memmap initialized.  That's why more time is
costed at the time.

[    0.008842] ACPI: SRAT: Node 0 PXM 0 [mem 0x00000000-0x0009ffff]
[    0.008842] ACPI: SRAT: Node 0 PXM 0 [mem 0x00100000-0xbfffffff]
[    0.008843] ACPI: SRAT: Node 0 PXM 0 [mem 0x100000000-0x55ffffffff]
[    0.008844] ACPI: SRAT: Node 1 PXM 1 [mem 0x5600000000-0xaaffffffff]
[    0.008844] ACPI: SRAT: Node 2 PXM 2 [mem 0xab00000000-0xfcffffffff]
[    0.008845] ACPI: SRAT: Node 2 PXM 2 [mem 0x10000000000-0x1033fffffff]

Now, let's add a parameter 'zone_end_pfn' to memmap_init_zone() to pass
down the real zone end pfn so that defer_init() can use it to judge
whether defer need be taken in zone wide.

Link: https://lkml.kernel.org/r/20201223080811.16211-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20201223080811.16211-2-bhe@redhat.com
Fixes: commit 73a6e474cb ("mm: memmap_init: iterate over memblock regions rather that check each PFN")
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: Rahul Gopakumar <gopakumarr@vmware.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-06 14:56:50 +01:00
..
acpi PM: ACPI: PCI: Drop acpi_pm_set_bridge_wakeup() 2020-12-30 11:54:05 +01:00
asm-generic Merge branch 'for-5.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu 2020-11-15 08:57:19 -08:00
clocksource
crypto
drm drm: drm_print.h: fix kernel-doc markups 2020-10-27 11:21:39 +01:00
dt-bindings ARM: Devicetree updates 2020-10-24 10:44:18 -07:00
keys
kunit kunit: fix display of failed expectations for strings 2020-11-10 13:45:15 -07:00
kvm ARM: 2020-10-23 11:17:56 -07:00
linux mm: memmap defer init doesn't work as expected 2021-01-06 14:56:50 +01:00
math-emu
media media: v4l2-fwnode: v4l2_fwnode_endpoint_parse caller must init vep argument 2020-12-30 11:53:11 +01:00
memory
misc
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2020-12-10 14:29:30 -08:00
pcmcia
ras
rdma RDMA/uverbs: Fix incorrect variable type 2020-12-30 11:53:47 +01:00
scsi scsi: libiscsi: Fix NOP race condition 2020-11-16 22:32:50 -05:00
soc net: mscc: ocelot: fix dropping of unknown IPv4 multicast on Seville 2020-12-05 15:41:34 -08:00
sound ASoC: Fixes for v5.11 2020-11-19 19:56:29 +01:00
target
trace trace: fix potenial dangerous pointer 2020-11-25 13:03:44 +01:00
uapi binder: add flag to clear buffer on txn complete 2020-12-30 11:54:09 +01:00
vdso
video gpu: ipu-v3: remove unused functions 2020-10-26 10:42:38 +01:00
xen xen/xenbus: Count pending messages for each watch 2020-12-30 11:54:27 +01:00