* Re: 3.8.3 and 3.9git occasional watchdog oops [not found] <201303142154.20501.arekm@maven.pl> @ 2013-04-04 22:23 ` Arkadiusz Miskiewicz 0 siblings, 0 replies; 6+ messages in thread From: Arkadiusz Miskiewicz @ 2013-04-04 22:23 UTC (permalink / raw) To: Wim Van Sebroeck; +Cc: linux-watchdog, linux-kernel On Thursday 14 of March 2013, Arkadiusz Miśkiewicz wrote: > Hi. > > Just hit watchdog related oops in 3.8.3 kernel. Unfortunately photos only. > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8942.JPG > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8941.JPG 3.9git from today isn't any better unfortunately: http://ixion.pld-linux.org/~arekm/watchdog-oops-3.9git.jpg > > oops started after I enabled systemd watchdog functionality. Cannot > reproduce easily. > > watchdog here (thinkpad t400) is: > iTCO_wdt: Found a ICH9M-E TCO device (Version=2, TCOBASE=0x1060) -- Arkadiusz Miśkiewicz, arekm / maven.pl -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.8.3 and 3.9git occasional watchdog oops @ 2013-04-04 22:23 ` Arkadiusz Miskiewicz 0 siblings, 0 replies; 6+ messages in thread From: Arkadiusz Miskiewicz @ 2013-04-04 22:23 UTC (permalink / raw) To: Wim Van Sebroeck; +Cc: linux-watchdog, linux-kernel On Thursday 14 of March 2013, Arkadiusz Miśkiewicz wrote: > Hi. > > Just hit watchdog related oops in 3.8.3 kernel. Unfortunately photos only. > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8942.JPG > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8941.JPG 3.9git from today isn't any better unfortunately: http://ixion.pld-linux.org/~arekm/watchdog-oops-3.9git.jpg > > oops started after I enabled systemd watchdog functionality. Cannot > reproduce easily. > > watchdog here (thinkpad t400) is: > iTCO_wdt: Found a ICH9M-E TCO device (Version=2, TCOBASE=0x1060) -- Arkadiusz Miśkiewicz, arekm / maven.pl ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.8.3 and 3.9git occasional watchdog oops 2013-04-04 22:23 ` Arkadiusz Miskiewicz @ 2013-04-05 1:59 ` Guenter Roeck -1 siblings, 0 replies; 6+ messages in thread From: Guenter Roeck @ 2013-04-05 1:59 UTC (permalink / raw) To: Arkadiusz Miskiewicz; +Cc: Wim Van Sebroeck, linux-watchdog, linux-kernel On Fri, Apr 05, 2013 at 12:23:30AM +0200, Arkadiusz Miskiewicz wrote: > On Thursday 14 of March 2013, Arkadiusz Miśkiewicz wrote: > > Hi. > > > > Just hit watchdog related oops in 3.8.3 kernel. Unfortunately photos only. > > > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8942.JPG > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8941.JPG > > 3.9git from today isn't any better unfortunately: > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.9git.jpg > > > > > oops started after I enabled systemd watchdog functionality. Cannot > > reproduce easily. > > > > watchdog here (thinkpad t400) is: > > iTCO_wdt: Found a ICH9M-E TCO device (Version=2, TCOBASE=0x1060) > > Wonder if there is a race condition in the watchdog driver: The watchdog device is opened before watchdog_register_device returns. I suspect systemd waits for a udev event, or by some other means detects that /dev/watchdog was created, and opens it immediately. I just have no idea where exactly the race condition, if there is one, is hiding. Or maybe I am completely off track. Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.8.3 and 3.9git occasional watchdog oops @ 2013-04-05 1:59 ` Guenter Roeck 0 siblings, 0 replies; 6+ messages in thread From: Guenter Roeck @ 2013-04-05 1:59 UTC (permalink / raw) To: Arkadiusz Miskiewicz; +Cc: Wim Van Sebroeck, linux-watchdog, linux-kernel On Fri, Apr 05, 2013 at 12:23:30AM +0200, Arkadiusz Miskiewicz wrote: > On Thursday 14 of March 2013, Arkadiusz Miśkiewicz wrote: > > Hi. > > > > Just hit watchdog related oops in 3.8.3 kernel. Unfortunately photos only. > > > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8942.JPG > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8941.JPG > > 3.9git from today isn't any better unfortunately: > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.9git.jpg > > > > > oops started after I enabled systemd watchdog functionality. Cannot > > reproduce easily. > > > > watchdog here (thinkpad t400) is: > > iTCO_wdt: Found a ICH9M-E TCO device (Version=2, TCOBASE=0x1060) > > Wonder if there is a race condition in the watchdog driver: The watchdog device is opened before watchdog_register_device returns. I suspect systemd waits for a udev event, or by some other means detects that /dev/watchdog was created, and opens it immediately. I just have no idea where exactly the race condition, if there is one, is hiding. Or maybe I am completely off track. Guenter ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.8.3 and 3.9git occasional watchdog oops 2013-04-05 1:59 ` Guenter Roeck @ 2013-04-06 3:47 ` Guenter Roeck -1 siblings, 0 replies; 6+ messages in thread From: Guenter Roeck @ 2013-04-06 3:47 UTC (permalink / raw) To: Arkadiusz Miskiewicz; +Cc: Wim Van Sebroeck, linux-watchdog, linux-kernel On Thu, Apr 04, 2013 at 06:59:59PM -0700, Guenter Roeck wrote: > On Fri, Apr 05, 2013 at 12:23:30AM +0200, Arkadiusz Miskiewicz wrote: > > On Thursday 14 of March 2013, Arkadiusz Miśkiewicz wrote: > > > Hi. > > > > > > Just hit watchdog related oops in 3.8.3 kernel. Unfortunately photos only. > > > > > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8942.JPG > > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8941.JPG > > > > 3.9git from today isn't any better unfortunately: > > > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.9git.jpg > > > > > > > > oops started after I enabled systemd watchdog functionality. Cannot > > > reproduce easily. > > > > > > watchdog here (thinkpad t400) is: > > > iTCO_wdt: Found a ICH9M-E TCO device (Version=2, TCOBASE=0x1060) > > > > > Wonder if there is a race condition in the watchdog driver: The watchdog device > is opened before watchdog_register_device returns. I suspect systemd waits for > a udev event, or by some other means detects that /dev/watchdog was created, > and opens it immediately. > > I just have no idea where exactly the race condition, if there is one, is > hiding. Or maybe I am completely off track. > I _think_ I understand the sequence of events. - The driver is the first watchdog driver to register. - watchdog_dev_register() gets called and creates the watchdog misc device by calling misc_register(). At that time, the matching character device (/dev/watchdog0) does not yet exist, and old_wdd is not set either. - Userspace gets an event and opens /dev/watchdog - watchdog_open() is called and sets sets wdd = old_wdd, which is still NULL, and tries to dereference it. Bang. If this is the problem, a simple fix would be to set old_wdd before calling misc_register(). Can you test a patch ? Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.8.3 and 3.9git occasional watchdog oops @ 2013-04-06 3:47 ` Guenter Roeck 0 siblings, 0 replies; 6+ messages in thread From: Guenter Roeck @ 2013-04-06 3:47 UTC (permalink / raw) To: Arkadiusz Miskiewicz; +Cc: Wim Van Sebroeck, linux-watchdog, linux-kernel On Thu, Apr 04, 2013 at 06:59:59PM -0700, Guenter Roeck wrote: > On Fri, Apr 05, 2013 at 12:23:30AM +0200, Arkadiusz Miskiewicz wrote: > > On Thursday 14 of March 2013, Arkadiusz Miśkiewicz wrote: > > > Hi. > > > > > > Just hit watchdog related oops in 3.8.3 kernel. Unfortunately photos only. > > > > > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8942.JPG > > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.8.3/IMG_8941.JPG > > > > 3.9git from today isn't any better unfortunately: > > > > http://ixion.pld-linux.org/~arekm/watchdog-oops-3.9git.jpg > > > > > > > > oops started after I enabled systemd watchdog functionality. Cannot > > > reproduce easily. > > > > > > watchdog here (thinkpad t400) is: > > > iTCO_wdt: Found a ICH9M-E TCO device (Version=2, TCOBASE=0x1060) > > > > > Wonder if there is a race condition in the watchdog driver: The watchdog device > is opened before watchdog_register_device returns. I suspect systemd waits for > a udev event, or by some other means detects that /dev/watchdog was created, > and opens it immediately. > > I just have no idea where exactly the race condition, if there is one, is > hiding. Or maybe I am completely off track. > I _think_ I understand the sequence of events. - The driver is the first watchdog driver to register. - watchdog_dev_register() gets called and creates the watchdog misc device by calling misc_register(). At that time, the matching character device (/dev/watchdog0) does not yet exist, and old_wdd is not set either. - Userspace gets an event and opens /dev/watchdog - watchdog_open() is called and sets sets wdd = old_wdd, which is still NULL, and tries to dereference it. Bang. If this is the problem, a simple fix would be to set old_wdd before calling misc_register(). Can you test a patch ? Guenter ^ permalink raw reply [flat|nested] 6+ messages in thread
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[not found] <201303142154.20501.arekm@maven.pl>
2013-04-04 22:23 ` 3.8.3 and 3.9git occasional watchdog oops Arkadiusz Miskiewicz
2013-04-04 22:23 ` Arkadiusz Miskiewicz
2013-04-05 1:59 ` Guenter Roeck
2013-04-05 1:59 ` Guenter Roeck
2013-04-06 3:47 ` Guenter Roeck
2013-04-06 3:47 ` Guenter Roeck
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