Re: [PATCH] activation: set children oom_score_adj to 0

On 06/07/2016 09:10 PM, Simon McVittie wrote:
> On 07/06/16 12:53, WaLyong Cho wrote:
>> If dbus is running as systemd service, dbus daemon is running with
>> oom_score_adj -900 by OOMScoreAdjust=-900. And children will also have
>> same value with dbus daemon.
>> To avoid this, set the child itself values after fork () to 0.
> 
> This looks like it might be intended to be a solution to the same issue
> as <https://bugs.freedesktop.org/show_bug.cgi?id=32851>. Please see
> Lennart's review comments on that bug: in particular, this should
> probably be #ifdef __linux__, and the file descriptor should be marked
> close-on-exec. Please attach any revised patches to that bug.

I will prepare next patch with #ifdef __linux__.

> 
> Is there any particular reason to have used buffered stdio here, and not
> open() + write()? Buffered I/O seems undesirable when writing to the
> /proc pseudo-filesystem.

I'm also thinking open() + write() more appropriate. I will change it.

> 
> I would normally suggest using _dbus_string_save_to_file(), but that
> uses the tempfile + atomic overwrite pattern, which won't work in /proc.
> 
I did not know this api. But to use _dbus_string_save_to_file(), new
DBusString value has to be declared. And it seems to be initialized with
_dbus_string_init() and filled with _dbus_string_copy() or
_dbus_string_append() and also destroied with _dbus_string_free(). I'm
not sure using _dbus_string_save_to_file() is good idea to set
/proc/self/oom_score_adj to 0.
But if you still suggest using _dbus_string_save_to_file(), I will use
_dbus_string_save_to_file().

Thanks
WaLyong
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