Re: [PATCH v8 0/4] introduce memory hinting API for external process

Oleksandr Natalenko
2020-06-23T09:07:36Z

On Mon, Jun 22, 2020 at 12:28:56PM -0700, Minchan Kim wrote:
> Now, we have MADV_PAGEOUT and MADV_COLD as madvise hinting API. With that,
> application could give hints to kernel what memory range are preferred to be
> reclaimed. However, in some platform(e.g., Android), the information
> required to make the hinting decision is not known to the app.
> Instead, it is known to a centralized userspace daemon(e.g., ActivityManagerService),
> and that daemon must be able to initiate reclaim on its own without any app
> involvement.
>
> To solve the concern, this patch introduces new syscall - process_madvise(2).
> Bascially, it's same with madvise(2) syscall but it has some differences.
>
> 1. It needs pidfd of target process to provide the hint
> 2. It supports only MADV_{COLD|PAGEOUT} at this moment.
> Other hints in madvise will be opened when there are explicit requests from
> community to prevent unexpected bugs we couldn't support.
> 3. Only privileged processes can do something for other process's address
> space.
>
> For more detail of the new API, please see "mm: introduce external memory hinting API"
> description in this patchset.
>
> * from v7 - http://lore.kernel.org/r/20200302193630.68771-1-minchan@kernel.org
> * dropping pid support from new syscall and fold releated patches into syscall patch
> * dropping KSM patch by discussion - Oleksandr, I lost the discussion.
> Please resend the single patch against of the patchset if you resolves the discussion.
> https://lore.kernel.org/linux-api/20200302193630.68771-8-minchan@kernel.org/

What "next" tag this (v8) submission is based on please?

> * from v6 - https://lore.kernel.org/linux-api/20200219014433.88424-1-minchan@kernel.org/
> * fix comments and descriptions - Suren
> * Add Reviewed-by - Suren
> * fix build break reported by 0-day
>
> * from v5 - https://lore.kernel.org/linux-mm/20200214170520.160271-1-minchan@kernel.org/
> * use null task and requestor's mm for io_madvise - Jann and Jens
> * use right commit description for moving pidfd_get_pid - Christoph
>
> * from v4 - https://lore.kernel.org/linux-mm/20200212233946.246210-1-minchan@kernel.org/
> * pass mm down to functions, not accessing task->mm - Jann
> * clean up - Alexander
> * add Reviewed-by - Alexander, SeongJae
> * patch reordering
>
> * from v3 - https://lore.kernel.org/linux-mm/20200128001641.5086-1-minchan@kernel.org/
> * verify task->mm aftere access_mm - Oleg
> * split some patches for easy review - Alexander
> * clean up fatal signal checking - Suren
>
> * from v2 - https://lore.kernel.org/linux-mm/20200116235953.163318-1-minchan@kernel.org/
> * check signal callee and caller to bail out - Kirill Tkhai
> * put more clarification for justification of new API
>
> * from v1 - https://lore.kernel.org/linux-mm/20200110213433.94739-1-minchan@kernel.org/
> * fix syscall number - SeongJae
> * use get_pid_task - Kirill Tkhai
> * extend API to support pid as well as pidfd - Kirill Tkhai
>
> Minchan Kim (4):
> mm/madvise: pass task and mm to do_madvise
> pid: move pidfd_get_pid() to pid.c
> mm/madvise: introduce process_madvise() syscall: an external memory
> hinting API
> mm/madvise: check fatal signal pending of target process
>
> arch/alpha/kernel/syscalls/syscall.tbl | 1 +
> arch/arm/tools/syscall.tbl | 1 +
> arch/arm64/include/asm/unistd.h | 2 +-
> arch/arm64/include/asm/unistd32.h | 2 +
> arch/ia64/kernel/syscalls/syscall.tbl | 1 +
> arch/m68k/kernel/syscalls/syscall.tbl | 1 +
> arch/microblaze/kernel/syscalls/syscall.tbl | 1 +
> arch/mips/kernel/syscalls/syscall_n32.tbl | 1 +
> arch/mips/kernel/syscalls/syscall_n64.tbl | 1 +
> arch/mips/kernel/syscalls/syscall_o32.tbl | 1 +
> arch/parisc/kernel/syscalls/syscall.tbl | 1 +
> arch/powerpc/kernel/syscalls/syscall.tbl | 1 +
> arch/s390/kernel/syscalls/syscall.tbl | 1 +
> arch/sh/kernel/syscalls/syscall.tbl | 1 +
> arch/sparc/kernel/syscalls/syscall.tbl | 1 +
> arch/x86/entry/syscalls/syscall_32.tbl | 1 +
> arch/x86/entry/syscalls/syscall_64.tbl | 2 +
> arch/xtensa/kernel/syscalls/syscall.tbl | 1 +
> fs/io_uring.c | 2 +-
> include/linux/compat.h | 4 +
> include/linux/mm.h | 3 +-
> include/linux/pid.h | 1 +
> include/linux/syscalls.h | 2 +
> include/uapi/asm-generic/unistd.h | 4 +-
> kernel/exit.c | 17 --
> kernel/pid.c | 17 ++
> kernel/sys_ni.c | 2 +
> mm/madvise.c | 190 +++++++++++++++++---
> 28 files changed, 217 insertions(+), 46 deletions(-)
>
> --
> 2.27.0.111.gc72c7da667-goog
>

--
Best regards,
Oleksandr Natalenko (post-factum)
Principal Software Maintenance Engineer