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
| ||
|
Date: Thu, 6 Nov 2008 01:41:49 +0100 From: "Frédéric Weisbecker" <fweisbec@...il.com> To: "Ingo Molnar" <mingo@...e.hu> Cc: "Steven Rostedt" <rostedt@...dmis.org>, "Linux Kernel" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] tracing: use raw spinlocks instead of spinlocks 2008/11/5 Ingo Molnar <mingo@...e.hu>: > > * Frédéric Weisbecker <fweisbec@...il.com> wrote: > >> 2008/11/4 Ingo Molnar <mingo@...e.hu>: >> > just make sure normal printk is totally silent. (otherwise you get >> > double lines on the console plus no reduction in recursion risk) >> > >> > i usually add a return; hack to kernel/printk.c:printk(), to make sure >> > it never executes anything. (and add a notrace to it as well) Maybe we >> > could even make this dependent on early_printk=...,keep. >> >> Thanks for your help! >> >> I tried the earlyprintk=vga,keep and I thought that the normal printk >> output would >> be replaced by early_printk output but that's not the case... >> So I replaced the content of printk by this of early_printk and it worked. >> But it seems that after the setting of the console, the early_printk >> doesn't work anymore. >> >> Should I disable something else? I haven't any console=.... parameter >> but I guess I missed >> something there... > > perhaps try a "console=tty 3" bootup - to boot into non-graphics > initlevel 3, and to have a vga tty set up. Then comment out the > regular printk(), to make sure it never tries to output to the regular > tty. > > does earlyprintk=vga,keep work in that case? > >> But, I set the parameter nmi_watchdog=2 (I didn't know I had to >> start explicitly the nmi watchdog) and at last... I had my >> backtraces :-) > > heh :-) > >> All these backtraces were related to time function. And one of the >> special things of the time functions is that they often manipulate >> 64 bits numbers. Actually I totally forgot that a function could >> return a long long, so I had to save edx register in the return >> handler to restore it in its end because 64 bits numbers are >> returned as a couple into eax and edx in x86-32. >> >> So the main problem is now solved. But it remains a last (but more >> rare) deadlock somewhere. I don't know why at this time and the nmi >> watchdog doesn't tell anything. So I will have to use early_printk >> to see the last functions traced. But the problem is that it doesn't >> print on the console... > > hm. Let me know if you cannot get this to work. I regularly use > earlyprintk=serial,...,keep myself, and it works there - but i dont > use earlyprintk=vga,keep that often. > > Ingo > Actually, I didn't need it. I just turned off the nmi watchdog and I don't have anymore deadlock. The good news is that I have now something that seems stable. I will have some time this week-end to try to make a proper patch with this feature. Thanks for your help! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists