Re: [PATCH v1] kernel/trace:check the val against the available mem

From: Steven Rostedt
Date: Wed Apr 04 2018 - 11:47:39 EST


On Wed, 4 Apr 2018 16:23:29 +0200
Michal Hocko <mhocko@xxxxxxxxxx> wrote:

> >
> > I tried it out, I did the following:
> >
> > set_current_oom_origin();
> > for (i = 0; i < nr_pages; i++) {
> > struct page *page;
> > /*
> > * __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails
> > * gracefully without invoking oom-killer and the system is not
> > * destabilized.
> > */
> > bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
> > GFP_KERNEL | __GFP_RETRY_MAYFAIL,
> > cpu_to_node(cpu));
> > if (!bpage)
> > goto free_pages;
> >
> > list_add(&bpage->list, pages);
> >
> > page = alloc_pages_node(cpu_to_node(cpu),
> > GFP_KERNEL | __GFP_RETRY_MAYFAIL, 0);
> > if (!page)
> > goto free_pages;
>
> if (fatal_signal_pending())
> fgoto free_pages;

I originally was going to remove the RETRY_MAYFAIL, but adding this
check (at the end of the loop though) appears to have OOM consistently
kill this task.

I still like to keep RETRY_MAYFAIL, because it wont trigger OOM if
nothing comes in and tries to do an allocation, but instead will fail
nicely with -ENOMEM.

-- Steve


>
> > bpage->page = page_address(page);
> > rb_init_page(bpage->page);
> > }
> > clear_current_oom_origin();