On Mon, 8 Jun 2015, Michal Hocko wrote: > > This patch is not a functional change, so I don't interpret your feedback > > as any support of it being merged. > > David, have you actually read the patch? The changelog is mentioning this: > " > check_panic_on_oom on the other hand will work and that is kind of > unexpected because sysrq+f should be usable to kill a mem hog whether > the global OOM policy is to panic or not. > It also doesn't make much sense to panic the system when no task cannot > be killed because admin has a separate sysrq for that purpose. > " > and the patch exludes panic_on_oom from the sysrq path. > Yes, and that's why I believe we should pursue that direction without the associated "cleanup" that adds 35 lines of code to supress a panic. In other words, there's no reason to combine a patch that suppresses the panic even with panic_on_oom, which I support, and a "cleanup" that I believe just obfuscates the code. It's a one-liner change: just test for force_kill and suppress the panic; we don't need 35 new lines that create even more unique entry paths. > > That said, you raise an interesting point of whether sysrq+f should ever > > trigger a panic due to panic_on_oom. The case can be made that it should > > ignore panic_on_oom and require the use of another sysrq to panic the > > machine instead. Sysrq+f could then be used to oom kill a process, > > regardless of panic_on_oom, and the panic only occurs if userspace did not > > trigger the kill or the kill itself will fail. > > Why would it panic the system if there is no killable task? Shoudln't > be admin able to do additional steps after the explicit oom killer failed > and only then panic by sysrq? > Today it panics, I don't think it should panic when there are no killable processes because it's inherently racy with userspace. It's similar to suppressing panic_on_oom for sysrq+f, but for a different reason, so it should probably be a separate patch with its own changelog (and update to documentation for both patches to make this explicit). -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>