From: Xiongwei Song <sxwjean@xxxxxxxxx>
Patch 1 is adding pfn_to_devmap_page() function to get page of ZONE_DEVICE
by pfn. It checks if dev_pagemap is valid, if yes, return page pointer.
Patch 2 is finishing supporting /proc/kpage* in exposing pages info of
ZONE_DEVICE to userspace.
The unit test has been done by "page-types -r", which ran in qemu with the
below arguments:
-object memory-backend-file,id=mem2,share,mem-path=./virtio_pmem.img,size=2G
-device virtio-pmem-pci,memdev=mem2,id=nv1
, which is used to emulate pmem device with 2G memory space.
As we know, the pages in ZONE_DEVICE are only set PG_reserved flag. So
before the serires,
run "page-types -r", the result is:
flags page-count MB symbolic-flags long-symbolic-flags
0x0000000100000000 24377 95 ___________________________r________________ reserved
, which means the only PG_reserved set of pages in system wide have 24377.
run "cat /proc/zoneinfo" to get the ZONE_DEVICE info:
Node 1, zone Device
pages free 0
boost 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
cma 0
protection: (0, 0, 0, 0, 0)
After this series,
run "page-types -r", the result is:
flags page-count MB symbolic-flags long-symbolic-flags
0x0000000100000000 548665 2143 ___________________________r________________ reserved
, which means the only PG_reserved set of pages in system wide have 548665.
Run "cat /proc/zoneinfo" to get the ZONE_DEVICE info:
Node 1, zone Device
pages free 0
boost 0
min 0
low 0
high 0
spanned 524288
present 0
managed 0
cma 0
protection: (0, 0, 0, 0, 0)
, these added pages number is 524288 in ZONE_DEVICE as spanned field
showed. Meanwhile, we can do 548665 - 24377 = 524288 that is increment
of the reserved pages, it equals to the spanned field of ZONE_DEVICE.
Hence it looks like the patchset works well.
v2 -> v3:
* Before returning page pointer, check validity of page by
pgmap_pfn_valid(). https://lkml.org/lkml/2022/1/10/853 .
v1 -> v2:
* Take David's suggestion to simplify the implementation of
pfn_to_devmap_page(). Please take a look at
https://lkml.org/lkml/2022/1/10/320 .
Xiongwei Song (2):
mm/memremap.c: Add pfn_to_devmap_page() to get page in ZONE_DEVICE
proc: Add getting pages info of ZONE_DEVICE support
fs/proc/page.c | 35 ++++++++++++++++++++-------------
include/linux/memremap.h | 8 ++++++++
mm/memremap.c | 42 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 72 insertions(+), 13 deletions(-)
--
2.30.2
