linux-kernel - Re: [PATCH 10/17] proc/fd: In proc_readfd_common use fnext

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <CAADnVQKAvzT5nYZhceL3P0z1Fosm2dqB+=U4R-fET2g8YO9HmA@mail.gmail.com>
Date:   Mon, 17 Aug 2020 21:59:09 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-Fsdevel <linux-fsdevel@...r.kernel.org>, criu@...nvz.org,
        bpf <bpf@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Jann Horn <jann@...jh.net>, Kees Cook <keescook@...omium.org>,
        Daniel P. Berrangé <berrange@...hat.com>,
        Jeff Layton <jlayton@...hat.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Matthew Wilcox <willy@...ian.org>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Matthew Wilcox <matthew@....cx>,
        Trond Myklebust <trond.myklebust@....uio.no>,
        Chris Wright <chrisw@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>
Subject: Re: [PATCH 10/17] proc/fd: In proc_readfd_common use fnext_task

On Mon, Aug 17, 2020 at 8:46 PM Eric W. Biederman <ebiederm@...ssion.com> wrote:
>
> I am definitely willing to look at it. Do we think there would be enough
> traffic on task_lock from /proc/<pid>/fd access to make it work doing?

not from /proc, but bpf iterator in kernel/bpf/task_iter.c that is
being modified
in the other patch is used to process 100+k tasks. The faster it can go
through them the better. We don't see task spin_lock being a bottleneck though.
To test it just do 'bpftool prog show'. It will use task iterator undercover.