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Tue, 23 Jun 2020 02:07:22 -0700 (PDT) Received: from localhost ([2001:470:5b39:29:79fc:ff4e:48ab:b845]) by smtp.gmail.com with ESMTPSA id z1sm13289301eji.92.2020.06.23.02.07.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Jun 2020 02:07:22 -0700 (PDT) Date: Tue, 23 Jun 2020 11:07:21 +0200 From: Oleksandr Natalenko To: Minchan Kim Cc: Andrew Morton , LKML , Christian Brauner , linux-mm , linux-api@vger.kernel.org, Suren Baghdasaryan , Tim Murray , Sandeep Patil , Sonny Rao , Brian Geffon , Michal Hocko , Johannes Weiner , Shakeel Butt , John Dias , Joel Fernandes , Jann Horn , alexander.h.duyck@linux.intel.com, sj38.park@gmail.com, David Rientjes , Arjun Roy Subject: Re: [PATCH v8 0/4] introduce memory hinting API for external process Message-ID: <20200623090721.5owt4cxjji6isqe3@butterfly.localdomain> References: <20200622192900.22757-1-minchan@kernel.org> MIME-Version: 1.0 In-Reply-To: <20200622192900.22757-1-minchan@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Queue-Id: 4AC931AD1B2 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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