From: Alexey Dobriyan <adobriyan@gmail.com>
To: Yang Shi <yang.shi@linux.alibaba.com>
Cc: akpm@linux-foundation.org, mingo@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fs: proc: use down_read_killable in proc_pid_cmdline_read()
Date: Fri, 23 Feb 2018 22:33:38 +0300 [thread overview]
Message-ID: <20180223193338.GA5708@avx2> (raw)
In-Reply-To: <b82e9c62-0c8d-205b-9887-8ea2c18eaccb@linux.alibaba.com>
On Wed, Feb 21, 2018 at 03:13:10PM -0800, Yang Shi wrote:
> >>> 2) access_remote_vm() et al will do the same ->mmap_sem, and
> >> Yes, it does. But, __access_remote_vm() is called by access_process_vm()
> >> too, which is used by much more places, i.e. ptrace, so I was not sure
> >> if it is preferred to convert to killable version. So, I leave it untouched.
> > Yeah, but ->mmap_sem is taken 3 times per /proc/*/cmdline read
> > and your scalability tests should trigger next backtrace right away.
>
> Yes, however, I didn't run into it if mmap_sem is acquired earlier.
>
> How about defining a killable version, like
> __access_remote_vm_killable() which use down_read_killable(), then the
> killable version can be used by proc/*/cmdline? There might be other
> users in the future.
It would be a disaster as interfaces multiply.
next prev parent reply other threads:[~2018-02-23 19:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-20 19:49 [PATCH] fs: proc: use down_read_killable in proc_pid_cmdline_read() Yang Shi
2018-02-20 22:38 ` Alexey Dobriyan
2018-02-20 23:38 ` Yang Shi
2018-02-21 19:57 ` Alexey Dobriyan
2018-02-21 23:13 ` Yang Shi
2018-02-23 19:33 ` Alexey Dobriyan [this message]
2018-02-23 19:42 ` Yang Shi
2018-02-23 19:45 ` Alexey Dobriyan
2018-02-23 20:08 ` Yang Shi
2018-02-23 18:28 ` Yang Shi
2018-02-20 23:57 ` Yang Shi
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