This is now being handed back to linux-mm for re-assessment.. OpenSSH devs are saying this is not a fault in their code.. It would appear that the loadable bnx2 module is causing strange oom_adj behavior.. and if its affecting this, I wonder what else it might be affecting? Bug can only be reproduced when the module is in use by actual hardware. Here is the latest conversation with openssh devs, which confirms this definitely falls within the remit of debian or kernel-mm. On 31/05/2011 13:25, Gert Doering wrote: > Hi, > > On Tue, May 31, 2011 at 12:11:13PM +0100, Cal Leeming [Simplicity Media Ltd] wrote: >> Could you point out the line of code where oom_adj_save is set to the >> original value, because I've looked everywhere, and from what I can >> tell, it's only ever set to INT_MIN, and no where else is it changed. >> (C is not my strongest language tho, so I most likely have overlooked >> something). This is where I got thrown off. > > oom_adjust_setup() does this: > > if ((fp = fopen(oom_adj_path, "r+")) != NULL) { > if (fscanf(fp, "%d", &oom_adj_save) != 1) > verbose("error reading %s: %s", oom_adj_path, > strerror(errno)); > > the "fscanf()" call will read an integer ("%d") from the file named, > and write that number into the variable being pointed to (&oom_adj_save). > > The loop is a bit tricky to read as it takes different paths into > account, and will exit after the first successful update. > > fscanf() will return the number of successful conversions, so if it > was able to read "one number", the return value is "1", and it will > jump to the else block > > else { > rewind(fp); > if (fprintf(fp, "%d\n", value) <= 0) > verbose("error writing %s: %s", > oom_adj_path, strerror(errno)); > else > verbose("Set %s from %d to %d", > oom_adj_path, oom_adj_save, value); > } > > where it will overwrite what is in that file with the new value > ("value"), and then print the "Set ... from -17 to -17" message that > you saw. Ah, thank you for explaining this. Makes a lot more sense now :) > > >>> The question here is why sshd is sometimes started with -17 and sometimes >>> with 0 - that's the bug, not that sshd keeps what it's given. >>> >>> (Ask yourself: if sshd had no idea about oom_adj at all, would this make >>> it buggy by not changing the value?) >> >> This was what I was trying to pinpoint down before. I had came to this >> conclusion myself, sent it to the Debian bug list, and they dismissed >> on the grounds that it was an openssh problem... > > I must admit that I have no idea what is causing it, but from the logs, > it very much looks like sshd is started with "-17" in there - but only > in the problem case. > > >> So far, the buck has been passed from kernel-mm to debian-kernel, to >> openssh, and now back to debian-kernel lol. The most annoying thing, >> is that you can't get this bug to happen unless you physically test on >> a machine which requires the bnx2 firmwire, so I get the feeling this >> won't get resolved :/ > > And *that* strongly points to a bug in the bnx2 stuff - if other programs > change their behaviour based on the existance of a given driver, that > does not smell very healthy. Agreed.. I was thinking of adding some debug into the fs/proc/ code which does a kprint on every oom_adj read/write, but I couldn't figure out how to extract the pid from the task (pointer?). > > [..] >>> Anyway, as a workaround for your system, you can certainly set >>> >>> oom_adj_save = 0; >>> >>> in the beginning of port-linux.c / oom_adjust_restore(), to claim that >>> "hey, this was the saved value to start with" and "restore" oom_adj to 0 >>> then - but that's just hiding the bug, not fixing it. >> >> I'm disappointed this wasn't the correct fix, I honestly thought I had >> patched it right :( > > Well, that's the short hand - "just ignore everything that happened at > init / save time, and forcibly write back '0', no matter what was there > before". > >> But, on the other hand, ssh users should really never have a default >> oom_adj of -17, so maybe 0 should be set as default anyway? If this is >> not the case, could you give reasons why?? > > Well, I would say "the default value in there is a matter of local policy", > so what if someone wants to make sure that whatever is run from sshd is > always privileged regarding oom, even if a local firefox etc. is running > amock and you need to ssh-in and kill the GUI stuff... > > One might opt to run sshd (and all its children) at "-5" (slightly special > treatment), or "0" (no special treatment), or even at "-17" - but that's > local policy. Ah, okay that's make sense. > > > Mmmh. > > Since this seems to be inherited, it might even work if you just change > the sshd startup script, and insert > > echo 0 >/proc/self/oom_adj > > in there, right before it starts the sshd... "local policy at work". Yeah I was going to do this, but then I thought "well if this problem is occurring for openssh, then what else could it be affecting?". As you pointed out above, having the oom_adj changed based on the existence of a driver is really not good. I will paste this convo trail into the debian ticket, and hopefully it'll help convince them this issue needs fixing. > > gert Thanks again for taking the time to reply! On 30/05/2011 22:36, Cal Leeming [Simplicity Media Ltd] wrote: > FYI everyone, I found a bug within openssh-server which caused this > problem. > > I've patched and submitted to the openssh list. > > You can find details of this by googling for: > "port-linux.c bug with oom_adjust_restore() - causes real bad oom_adj > - which can cause DoS conditions" > > It's extremely strange.. :S > > Cal > > On 30/05/2011 18:36, Cal Leeming [Simplicity Media Ltd] wrote: >> Here is an strace of the SSH process (which is somehow inheriting the >> -17 oom_adj on all forked user instances) >> >> (broken server - with bnx2 module loaded) >> [pid 2200] [ 7f13a09c9cb0] open("/proc/self/oom_adj", >> O_WRONLY|O_CREAT|O_TRUNC, 0666 >> [pid 2120] [ 7f13a09c9f00] write(7, "\0\0\2\240\n\n\n\nPort >> 22\n\n\n\nProtocol 2\n\nH"..., 680 >> [pid 2200] [ 7f13a09c9cb0] <... open resumed> ) = 9 >> [pid 2120] [ 7f13a09c9f00] <... write resumed> ) = 680 >> [pid 2120] [ 7f13a09c9e40] close(7 >> [pid 2200] [ 7f13a09c9844] fstat(9, >> [pid 2120] [ 7f13a09c9e40] <... close resumed> ) = 0 >> [pid 2200] [ 7f13a09c9844] <... fstat resumed> >> {st_mode=S_IFREG|0644, st_size=0, ...}) = 0 >> [pid 2120] [ 7f13a09c9e40] close(8 >> [pid 2200] [ 7f13a09d2a2a] mmap(NULL, 4096, PROT_READ|PROT_WRITE, >> MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 >> [pid 2120] [ 7f13a09c9e40] <... close resumed> ) = 0 >> [pid 2200] [ 7f13a09d2a2a] <... mmap resumed> ) = 0x7f13a25a6000 >> [pid 2120] [ 7f13a09c9e40] close(4 >> [pid 2200] [ 7f13a09c9f00] write(9, "-17\n", 4 >> >> >> (working server - with bnx2 module unloaded) >> [pid 1323] [ 7fae577fbe40] close(7) = 0 >> [pid 1631] [ 7fae577fbcb0] open("/proc/self/oom_adj", >> O_WRONLY|O_CREAT|O_TRUNC, 0666 >> [pid 1323] [ 7fae577fbf00] write(8, "\0\0\2\217\0", 5 > ...> >> [pid 1631] [ 7fae577fbcb0] <... open resumed> ) = 10 >> [pid 1323] [ 7fae577fbf00] <... write resumed> ) = 5 >> [pid 1323] [ 7fae577fbf00] write(8, "\0\0\2\206\n\n\n\nPort >> 22\n\n\n\nProtocol 2\n\nH"..., 654 >> [pid 1631] [ 7fae577fb844] fstat(10, >> [pid 1323] [ 7fae577fbf00] <... write resumed> ) = 654 >> [pid 1631] [ 7fae577fb844] <... fstat resumed> >> {st_mode=S_IFREG|0644, st_size=0, ...}) = 0 >> [pid 1323] [ 7fae577fbe40] close(8) = 0 >> [pid 1631] [ 7fae57804a2a] mmap(NULL, 4096, PROT_READ|PROT_WRITE, >> MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 >> [pid 1323] [ 7fae577fbe40] close(9 >> [pid 1631] [ 7fae57804a2a] <... mmap resumed> ) = 0x7fae593d9000 >> [pid 1323] [ 7fae577fbe40] <... close resumed> ) = 0 >> [pid 1323] [ 7fae577fbe40] close(5 >> [pid 1631] [ 7fae577fbf00] write(10, "0\n", 2 >> >> The two servers are *EXACT* duplicates of each other, completely >> fresh Debian installs, with exactly the same packages installed. >> >> As you can see, the working server sends "0" into the oom_adj and the >> broken one sends "-17". >> >> >> On 30/05/2011 15:27, Cal Leeming [Simplicity Media Ltd] wrote: >>> I FOUND THE PROBLEM!!! >>> >>> Explicit details can be found on the Debian kernel mailing list, but >>> to cut short, it's caused by the firmware-bnx2 kernel module: >>> >>> The broken server uses 'firmware-bnx2'.. so I purged the bnx2 >>> package, removed the bnx*.ko files from /lib/modules, ran >>> update-initramfs, and then rebooted (i then confirmed it was removed >>> by checking ifconfig and lsmod). >>> >>> And guess what.. IT WORKED. >>> >>> So, this problem seems to be caused by the firmware-bnx2 module >>> being loaded.. some how, that module is causing -17 oom_adj to be >>> set for everything.. >>> >>> WTF?!?! Surely a bug?? Could someone please forward this to the >>> appropriate person for the bnx2 kernel module, as I wouldn't even >>> know where to begin :S >>> >>> Cal >>> >>> On 30/05/2011 11:52, Cal Leeming [Simplicity Media Ltd] wrote: >>>> -resent due to incorrect formatting, sorry if this dups! >>>> >>>> @Kame >>>> Thanks for the reply! >>>> Both kernels used the same env/dist, but which slightly different >>>> packages. >>>> After many frustrating hours, I have pin pointed this down to a dodgy >>>> Debian package which appears to continue affecting the system, even >>>> after purging. I'm still yet to pin point the package down (I'm doing >>>> several reinstall tests, along with tripwire analysis after each >>>> reboot). >>>> >>>> @Hiroyuki >>>> Thank you for sending this to the right people! >>>> >>>> @linux-mm >>>> On a side note, would someone mind taking a few minutes to give a >>>> brief explanation as to how the default oom_adj is set, and under what >>>> conditions it is given -17 by default? Is this defined by the >>>> application? I looked through the kernel source, >>>> and noticed some of the code was defaulted to set oom_adj to >>>> OOM_DISABLE (which is defined in the headers as -17). >>>> >>>> Assuming the debian problem is resolved, this might be another call >>>> for the oom-killer to be modified so that if it encounters the >>>> unrecoverable loop, it ignores the -17 rule (with some exceptions, >>>> such as kernel processes, and other critical things). If this is going >>>> to be a relatively simple task, I wouldn't mind spending a few hours >>>> patching this? >>>> >>>> Cal >>>> >>>> On Mon, May 30, 2011 at 3:23 AM, KAMEZAWA Hiroyuki >>>> wrote: >>>>> Thank you. memory cgroup and OOM troubles are handled in linux-mm. >>>>> >>>>> On Sun, 29 May 2011 23:24:07 +0100 >>>>> "Cal Leeming [Simplicity Media >>>>> Ltd]" wrote: >>>>> >>>>>> Some further logs: >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.369927] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.369939] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.399285] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.399296] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.428690] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.428702] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.487696] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.487708] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.517023] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.517035] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.546379] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:38 vicky kernel: [ 2283.546391] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.310789] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.310804] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.369918] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.369930] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.399284] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.399296] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.433634] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.433648] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.463947] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.463959] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.493439] >>>>>> redis-server >>>>>> invoked oom-killer: gfp_mask=0xd0, order=0, oom_adj=-17 >>>>>> ./log/syslog:May 30 07:44:43 vicky kernel: [ 2288.493451] >>>>>> [] ? oom_kill_process+0x82/0x283 >>>>>> >>>>>> >>>>> hmm, in short, applications has -17 oom_adj in default with >>>>> 2.6.32.41 ? >>>>> AFAIK, no kernel has such crazy settings as default.. >>>>> >>>>> Does your 2 kernel uses the same environment/distribution ? >>>>> >>>>> Thanks, >>>>> -Kame >>>>> >>>>>> On 29/05/2011 22:50, Cal Leeming [Simplicity Media Ltd] wrote: >>>>>>> First of all, my apologies if I have submitted this problem to >>>>>>> the >>>>>>> wrong place, spent 20 minutes trying to figure out where it >>>>>>> needs to >>>>>>> be sent, and was still none the wiser. >>>>>>> >>>>>>> The problem is related to applying memory limitations within a >>>>>>> cgroup. >>>>>>> If the OOM killer kicks in, it gets stuck in a loop where it >>>>>>> tries to >>>>>>> kill a process which has an oom_adj of -17. This causes an infinite >>>>>>> loop, which in turn locks up the system. >>>>>>> >>>>>>> May 30 03:13:08 vicky kernel: [ 1578.117055] Memory cgroup out of >>>>>>> memory: kill process 6016 (java) score 0 or a child >>>>>>> May 30 03:13:08 vicky kernel: [ 1578.117154] Memory cgroup out of >>>>>>> memory: kill process 6016 (java) score 0 or a child >>>>>>> May 30 03:13:08 vicky kernel: [ 1578.117248] Memory cgroup out of >>>>>>> memory: kill process 6016 (java) score 0 or a child >>>>>>> May 30 03:13:08 vicky kernel: [ 1578.117343] Memory cgroup out of >>>>>>> memory: kill process 6016 (java) score 0 or a child >>>>>>> May 30 03:13:08 vicky kernel: [ 1578.117441] Memory cgroup out of >>>>>>> memory: kill process 6016 (java) score 0 or a child >>>>>>> >>>>>>> >>>>>>> root@vicky [/home/foxx]> uname -a >>>>>>> Linux vicky 2.6.32.41-grsec #3 SMP Mon May 30 02:34:43 BST 2011 >>>>>>> x86_64 >>>>>>> GNU/Linux >>>>>>> (this happens on both the grsec patched and non patched >>>>>>> 2.6.32.41 kernel) >>>>>>> >>>>>>> When this is encountered, the memory usage across the whole >>>>>>> server is >>>>>>> still within limits (not even hitting swap). >>>>>>> >>>>>>> The memory configuration for the cgroup/lxc is: >>>>>>> lxc.cgroup.memory.limit_in_bytes = 3000M >>>>>>> lxc.cgroup.memory.memsw.limit_in_bytes = 3128M >>>>>>> >>>>>>> Now, what is even more strange, is that when running under the >>>>>>> 2.6.32.28 kernel (both patched and unpatched), this problem doesn't >>>>>>> happen. However, there is a slight difference between the two >>>>>>> kernels. >>>>>>> The 2.6.32.28 kernel gives a default of 0 in the /proc/X/oom_adj, >>>>>>> where as the 2.6.32.41 gives a default of -17. I suspect this is >>>>>>> the >>>>>>> root cause of why it's showing in the later kernel, but not the >>>>>>> earlier. >>>>>>> >>>>>>> To test this theory, I started up the lxc on both servers, and then >>>>>>> ran a one liner which showed me all the processes with an >>>>>>> oom_adj of -17: >>>>>>> >>>>>>> (the below is the older/working kernel) >>>>>>> root@courtney.internal [/mnt/encstore/lxc]> uname -a >>>>>>> Linux courtney.internal 2.6.32.28-grsec #3 SMP Fri Feb 18 >>>>>>> 16:09:07 GMT >>>>>>> 2011 x86_64 GNU/Linux >>>>>>> root@courtney.internal [/mnt/encstore/lxc]> for x in `find /proc >>>>>>> -iname 'oom_adj' | xargs grep "\-17" | awk -F '/' '{print $3}'` >>>>>>> ; do >>>>>>> ps -p $x --no-headers ; done >>>>>>> grep: /proc/1411/task/1411/oom_adj: No such file or directory >>>>>>> grep: /proc/1411/oom_adj: No such file or directory >>>>>>> 804 ? 00:00:00 udevd >>>>>>> 804 ? 00:00:00 udevd >>>>>>> 25536 ? 00:00:00 sshd >>>>>>> 25536 ? 00:00:00 sshd >>>>>>> 31861 ? 00:00:00 sshd >>>>>>> 31861 ? 00:00:00 sshd >>>>>>> 32173 ? 00:00:00 udevd >>>>>>> 32173 ? 00:00:00 udevd >>>>>>> 32174 ? 00:00:00 udevd >>>>>>> 32174 ? 00:00:00 udevd >>>>>>> >>>>>>> (the below is the newer/broken kernel) >>>>>>> root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> uname -a >>>>>>> Linux vicky 2.6.32.41-grsec #3 SMP Mon May 30 02:34:43 BST 2011 >>>>>>> x86_64 >>>>>>> GNU/Linux >>>>>>> root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> for x in >>>>>>> `find /proc -iname 'oom_adj' | xargs grep "\-17" | awk -F '/' >>>>>>> '{print >>>>>>> $3}'` ; do ps -p $x --no-headers ; done >>>>>>> grep: /proc/3118/task/3118/oom_adj: No such file or directory >>>>>>> grep: /proc/3118/oom_adj: No such file or directory >>>>>>> 895 ? 00:00:00 udevd >>>>>>> 895 ? 00:00:00 udevd >>>>>>> 1091 ? 00:00:00 udevd >>>>>>> 1091 ? 00:00:00 udevd >>>>>>> 1092 ? 00:00:00 udevd >>>>>>> 1092 ? 00:00:00 udevd >>>>>>> 2596 ? 00:00:00 sshd >>>>>>> 2596 ? 00:00:00 sshd >>>>>>> 2608 ? 00:00:00 sshd >>>>>>> 2608 ? 00:00:00 sshd >>>>>>> 2613 ? 00:00:00 sshd >>>>>>> 2613 ? 00:00:00 sshd >>>>>>> 2614 pts/0 00:00:00 bash >>>>>>> 2614 pts/0 00:00:00 bash >>>>>>> 2620 pts/0 00:00:00 sudo >>>>>>> 2620 pts/0 00:00:00 sudo >>>>>>> 2621 pts/0 00:00:00 su >>>>>>> 2621 pts/0 00:00:00 su >>>>>>> 2622 pts/0 00:00:00 bash >>>>>>> 2622 pts/0 00:00:00 bash >>>>>>> 2685 ? 00:00:00 lxc-start >>>>>>> 2685 ? 00:00:00 lxc-start >>>>>>> 2699 ? 00:00:00 init >>>>>>> 2699 ? 00:00:00 init >>>>>>> 2939 ? 00:00:00 rc >>>>>>> 2939 ? 00:00:00 rc >>>>>>> 2942 ? 00:00:00 startpar >>>>>>> 2942 ? 00:00:00 startpar >>>>>>> 2964 ? 00:00:00 rsyslogd >>>>>>> 2964 ? 00:00:00 rsyslogd >>>>>>> 2964 ? 00:00:00 rsyslogd >>>>>>> 2964 ? 00:00:00 rsyslogd >>>>>>> 2980 ? 00:00:00 startpar >>>>>>> 2980 ? 00:00:00 startpar >>>>>>> 2981 ? 00:00:00 ctlscript.sh >>>>>>> 2981 ? 00:00:00 ctlscript.sh >>>>>>> 3016 ? 00:00:00 cron >>>>>>> 3016 ? 00:00:00 cron >>>>>>> 3025 ? 00:00:00 mysqld_safe >>>>>>> 3025 ? 00:00:00 mysqld_safe >>>>>>> 3032 ? 00:00:00 sshd >>>>>>> 3032 ? 00:00:00 sshd >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3097 ? 00:00:00 mysqld.bin >>>>>>> 3113 ? 00:00:00 ctl.sh >>>>>>> 3113 ? 00:00:00 ctl.sh >>>>>>> 3115 ? 00:00:00 sleep >>>>>>> 3115 ? 00:00:00 sleep >>>>>>> 3116 ? 00:00:00 .memcached.bin >>>>>>> 3116 ? 00:00:00 .memcached.bin >>>>>>> >>>>>>> >>>>>>> As you can see, it is clear that the newer kernel is setting -17 by >>>>>>> default, which in turn is causing the OOM killer loop. >>>>>>> >>>>>>> So I began to try and find what may have caused this problem by >>>>>>> comparing the two sources... >>>>>>> >>>>>>> I checked the code for all references to 'oom_adj' and >>>>>>> 'oom_adjust' in >>>>>>> both code sets, but found no obvious differences: >>>>>>> grep -R -e oom_adjust -e oom_adj . | sort | grep -R -e >>>>>>> oom_adjust -e >>>>>>> oom_adj >>>>>>> >>>>>>> Then I checked for references to "-17" in all .c and .h files, and >>>>>>> found a couple of matches, but only one obvious one: >>>>>>> grep -R "\-17" . | grep -e ".c:" -e ".h:" -e "\-17" | wc -l >>>>>>> ./include/linux/oom.h:#define OOM_DISABLE (-17) >>>>>>> >>>>>>> But again, a search for OOM_DISABLE came up with nothing obvious... >>>>>>> >>>>>>> In a last ditch attempt, I did a search for all references to 'oom' >>>>>>> (case-insensitive) in both code bases, then compared the two: >>>>>>> root@annabelle [~/lol/linux-2.6.32.28]> grep -i -R "oom" . | >>>>>>> sort -n >>>>>>>> /tmp/annabelle.oom_adj >>>>>>> root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> grep >>>>>>> -i -R >>>>>>> "oom" . | sort -n> /tmp/vicky.oom_adj >>>>>>> >>>>>>> and this brought back (yet again) nothing obvious.. >>>>>>> >>>>>>> >>>>>>> root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> md5sum >>>>>>> ./include/linux/oom.h >>>>>>> 2a32622f6cd38299fc2801d10a9a3ea8 ./include/linux/oom.h >>>>>>> >>>>>>> root@annabelle [~/lol/linux-2.6.32.28]> md5sum >>>>>>> ./include/linux/oom.h >>>>>>> 2a32622f6cd38299fc2801d10a9a3ea8 ./include/linux/oom.h >>>>>>> >>>>>>> root@vicky [/mnt/encstore/ssd/kernel/linux-2.6.32.41]> md5sum >>>>>>> ./mm/oom_kill.c >>>>>>> 1ef2c2bec19868d13ec66ec22033f10a ./mm/oom_kill.c >>>>>>> >>>>>>> root@annabelle [~/lol/linux-2.6.32.28]> md5sum ./mm/oom_kill.c >>>>>>> 1ef2c2bec19868d13ec66ec22033f10a ./mm/oom_kill.c >>>>>>> >>>>>>> >>>>>>> >>>>>>> Could anyone please shed some light as to why the default >>>>>>> oom_adj is >>>>>>> set to -17 now (and where it is actually set)? From what I can >>>>>>> tell, >>>>>>> the fix for this issue will either be: >>>>>>> >>>>>>> 1. Allow OOM killer to override the decision of ignoring >>>>>>> oom_adj == >>>>>>> -17 if an unrecoverable loop is encountered. >>>>>>> 2. Change the default back to 0. >>>>>>> >>>>>>> Again, my apologies if this bug report is slightly unorthodox, or >>>>>>> doesn't follow usual procedure etc. I can assure you I have >>>>>>> tried my >>>>>>> absolute best to give all the necessary information though. >>>>>>> >>>>>>> Cal >>>>>>> >>>>>> -- >>>>>> To unsubscribe from this list: send the line "unsubscribe >>>>>> linux-kernel" in >>>>>> the body of a message to majordomo@vger.kernel.org >>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>>> Please read the FAQ at http://www.tux.org/lkml/ >>>>>> >>> >> >