On Fri, Dec 02, 2011 at 02:44:41PM +0900, KAMEZAWA Hiroyuki wrote: > On Fri, 2 Dec 2011 14:31:48 +1100 > Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > > So, it's a distro bug - sshd should never be started from from udev > > context because of this inherited oom_score_adj thing. > > Interestingly, the ifup ssh restart script says this: > > > > # We'd like to use 'reload' here, but it has some problems; see #502444. > > if [ -x /usr/sbin/invoke-rc.d ]; then > > invoke-rc.d ssh restart >/dev/null 2>&1 || true > > else > > /etc/init.d/ssh restart >/dev/null 2>&1 || true > > fi > > > > Bug 502444 describes the exact startup race condition that I've just > > found. It does a ssh server restart because reload causes the sshd > > server to fail to start if a start is currently in progress. So, > > rather than solving the start vs reload race condition, it got a > > bandaid (use restart to restart sshd from the reload context) and > > left it as a landmine..... > > > > Thank you for chasing. > Hm, BTW, do you think this kind of tracepoint is useful for debugging ? > This patch is just an example. Definitely a good idea, because not all applications have logging like sshd does. Besides, the first thing I went looking for was tracepoints. ;) > > == > From ed565cbf842e0b30827fba7bfdbc724fe21d9d2d Mon Sep 17 00:00:00 2001 > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> > Date: Fri, 2 Dec 2011 14:10:51 +0900 > Subject: [PATCH] oom_score_adj trace point. > > oom_score_adj is set by some daemon and launch tasks ans inherited > to applications, sometimes unexpectedly. > > This patch is for debugging oom_score_adj inheritance. This > adds trace points for oom_score_adj inheritance. > > bash-2501 [002] 448.860197: oom_score_adj_update: task 2501[bash] updates oom_score_adj=-1000 > bash-2501 [002] 455.678190: oom_score_adj_inherited: new task 2527 inherited oom_score_adj -1000 > ls-2527 [007] 455.678683: oom_score_task_rename: task 2527[bash] to [ls] oom_score_adj=-1000 > bash-2501 [007] 461.632103: oom_score_adj_inherited: new task 2528 inherited oom_score_adj -1000 > bash-2501 [007] 461.632335: oom_score_adj_inherited: new task 2529 inherited oom_score_adj -1000 > ls-2528 [003] 461.632983: oom_score_task_rename: task 2528[bash] to [ls] oom_score_adj=-1000 > less-2529 [005] 461.633086: oom_score_task_rename: task 2529[bash] to [less] oom_score_adj=-1000 > bash-2501 [004] 474.888710: oom_score_adj_update: task 2501[bash] updates oom_score_adj=0 > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Acked-by: Dave Chinner <dchinner@xxxxxxxxxx> Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>