On 2014/6/23 18:50, Zhang Zhen wrote: > On 2014/6/20 18:30, David Rientjes wrote: >> On Fri, 20 Jun 2014, Zhang Zhen wrote: >> >>> Hi, >>> >>> I am testing mem-hotplug on a qemu virtual machine. I executed the following command >>> to notify memory hot-add event by hand. >>> >>> % echo start_address_of_new_memory > /sys/devices/system/memory/probe >>> >>> To a different start_address_of_new_memory I got different results. >>> The results are as follows: >>> >>> MBSC-x86_64 /sys/devices/system/memory # ls >>> block_size_bytes memory2 memory5 power >>> memory0 memory3 memory6 probe >>> memory1 memory4 memory7 uevent >>> MBSC-x86_64 /sys/devices/system/memory # echo 0x70000000 > probe >> >> Since block_size_bytes is 0x8000000 == 128MB, this is 0x70000000 / >> 0x8000000 = section number 14. Successfully hot added. Presumably you're >> reporting that there is no physical memory there, so this would default to >> the online node of the first memory block, probably node 0. >> >>> MBSC-x86_64 /sys/devices/system/memory # echo 0x78000000 > probe >>> -sh: echo: write error: File exists >> >> EEXIST gets returned when the resource already exists, mostly likely >> system RAM or reserved memory as reported by your BIOS. You report this >> is a 2GB machine, no reason to believe memory at 1920MB isn't already >> online (including reserved). >> >>> MBSC-x86_64 /sys/devices/system/memory # echo 0x80000000 > probe >>> -sh: echo: write error: File exists >>> MBSC-x86_64 /sys/devices/system/memory # echo 0x88000000 > probe >>> -sh: echo: write error: File exists >> >> Same. >> >>> MBSC-x86_64 /sys/devices/system/memory # echo 0x8f000000 > probe >>> -sh: echo: write error: Invalid argument >> >> Returns EINVAL because it's not a multiple of block_size_bytes, it's not >> aligned properly. >> >>> MBSC-x86_64 /sys/devices/system/memory # echo 0x90000000 > probe >>> -sh: echo: write error: File exists >> >> See above, the resoure already exists. Check your e820 your dmesg, which >> is missing from this report, to determine what already exists and may be >> already online or reserved. >> >>> MBSC-x86_64 /sys/devices/system/memory # echo 0xff0000000 > probe >> >> 0xff0000000 / 0x8000000 is section 510, successfully onlined. >> >>> MBSC-x86_64 /sys/devices/system/memory # ls >>> block_size_bytes memory2 memory510 probe >>> memory0 memory3 memory6 uevent >>> memory1 memory4 memory7 >>> memory14 memory5 power >> >> Looks good, you onlined sections 14 and 510 above. >> >>> MBSC-x86_64 /sys/devices/system/memory # echo 0xfff0000000 > probe >> >> Same for section 8190. >> >>> MBSC-x86_64 /sys/devices/system/memory # ls >>> block_size_bytes memory2 memory510 power >>> memory0 memory3 memory6 probe >>> memory1 memory4 memory7 uevent >>> memory14 memory5 memory8190 >>> >> >> Confirmed it's onlined. >> >>> The qemu virtual machine's physical memory size is 2048M, and the boot memory is 1024M. >>> >>> MBSC-x86_64 / # cat /proc/meminfo >>> MemTotal: 1018356 kB >>> MBSC-x86_64 / # cat /sys/devices/system/memory/block_size_bytes >>> 8000000 >>> >> >> That's irrelevant, you've explicitly onlined memory that doesn't exist. >> Not sure why you're using the probe interface unless you need it for x86, >> is ACPI not registering it correctly? >> >>> Three questions: >>> 1. The machine's physical memory size is 2048M, why echo 0x78000000 as the start_address_of_new_memory failed ? >>> >> >> Copy your e820 map from your dmesg, it's probably reserved or already >> online, this is lower than 2048M. >> > > Hi David, > > You are right, if we echo 0x78000000 as the start_address_of_new_memory, the end_address_of_new_memory is exceeded > the usable range. > Thank you for your comments. > > My e820 map as follows: > > [ 0.000000] e820: BIOS-provided physical RAM map: > [ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable > [ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved > [ 0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved > [ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000007fffdfff] usable > [ 0.000000] BIOS-e820: [mem 0x000000007fffe000-0x000000007fffffff] reserved > [ 0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved > [ 0.000000] e820: remove [mem 0x40000000-0xfffffffffffffffe] usable > [ 0.000000] NX (Execute Disable) protection: active > [ 0.000000] e820: user-defined physical RAM map: > [ 0.000000] user: [mem 0x0000000000000000-0x000000000009fbff] usable > [ 0.000000] user: [mem 0x000000000009fc00-0x000000000009ffff] reserved > [ 0.000000] user: [mem 0x00000000000f0000-0x00000000000fffff] reserved > [ 0.000000] user: [mem 0x0000000000100000-0x000000003fffffff] usable > [ 0.000000] user: [mem 0x000000007fffe000-0x000000007fffffff] reserved > [ 0.000000] user: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved > >>> 2. Why echo 0x8f000000 as the start_address_of_new_memory, the error message is different ? >>> >> >> Not properly aligned to block_size_bytes. It's a nuance, but >> block_size_bytes is exported in hex, not decimal. > > You are right, it's not properly aligned to block_size_bytes. I have made a mistake. > >> >>> 3. Why echo 0xfff0000000 as the start_address_of_new_memory succeeded ? 0xfff0000000 has exceeded the machine's physical memory size. >>> >> >> You're telling the kernel differently. >> > > I'm not clearly here, 0xfff0000000 is exceeded the usable range [mem 0x0000000000100000-0x000000007fffdfff] usable. > So i think here should return "File exists", but it succeeded. > > Is it properly ? > I got it, the address's validity should be guaranteed by me. Right? Thank you. > Best regards! > >> . >> > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. 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