On Wed 08-07-15 16:37:49, David Rientjes wrote: > On Wed, 8 Jul 2015, Michal Hocko wrote: > > > From: Michal Hocko <[email protected]> > > > > A github user rfjakob has reported the following issue via IRC. > > <rfjakob> Manually triggering the OOM killer does not work anymore in 4.0.5 > > <rfjakob> This is what it looks like: > > https://gist.github.com/rfjakob/346b7dc611fc3cdf4011 > > <rfjakob> Basically, what happens is that the GPU driver frees some memory, > > that satisfies the OOM killer > > <rfjakob> But the memory is allocated immediately again, and in the, no > > processes are killed no matter how often you trigger the oom killer > > <rfjakob> "in the end" > > > > Quoting from the github: > > " > > [19291.202062] sysrq: SysRq : Manual OOM execution > > [19291.208335] Purging GPU memory, 74399744 bytes freed, 8728576 bytes > > still pinned. > > [19291.390767] sysrq: SysRq : Manual OOM execution > > [19291.396792] Purging GPU memory, 74452992 bytes freed, 8728576 bytes > > still pinned. > > [19291.560349] sysrq: SysRq : Manual OOM execution > > [19291.566018] Purging GPU memory, 75489280 bytes freed, 8728576 bytes > > still pinned. > > [19291.729944] sysrq: SysRq : Manual OOM execution > > [19291.735686] Purging GPU memory, 74399744 bytes freed, 8728576 bytes > > still pinned. > > [19291.918637] sysrq: SysRq : Manual OOM execution > > [19291.924299] Purging GPU memory, 74403840 bytes freed, 8728576 bytes > > still pinned. > > " > > > > The issue is that sysrq+f (force_kill) gets confused by the regular OOM > > heuristic which tries to prevent from OOM killer if some of the oom > > notifier can relase a memory. The heuristic doesn't make much sense for > > the sysrq+f path because this one is used by the administrator to kill > > a memory hog. > > > > Reported-by: Jakob Unterwurzacher <[email protected]> > > Signed-off-by: Michal Hocko <[email protected]> > > Nack, the oom notify list has no place in the oom killer, it should be > called in the page allocator before calling out_of_memory().
I cannot say I would like oom notifiers interface. Quite contrary, it is just a crude hack. It is living outside of the shrinker interface which is what the reclaim is using and it acts like the last attempt before OOM (e.g. i915_gem_shrinker_init registers both "shrinkers"). So I am not sure it belongs outside of the oom killer proper. Besides that out_of_memory already contains shortcuts to prevent killing a task. Why is this any different? I mean why shouldn't callers of out_of_memory check whether the task is killed or existing before calling out_of_memory? -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
