Messages in this thread | | | Subject | Re: [PATCH 3/3] mm: oom: show unreclaimable slab info when unreclaimable slabs > user memory | From | "Yang Shi" <> | Date | Tue, 10 Oct 2017 02:53:18 +0800 |
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On 10/8/17 11:36 PM, Michal Hocko wrote: > On Mon 09-10-17 08:33:16, Michal Hocko wrote: >> On Sat 07-10-17 00:37:55, Yang Shi wrote: >>> >>> >>> On 10/6/17 2:37 AM, Michal Hocko wrote: >>>> On Thu 05-10-17 05:29:10, Yang Shi wrote: >> [...] >>>>> + list_for_each_entry_safe(s, s2, &slab_caches, list) { >>>>> + if (!is_root_cache(s) || (s->flags & SLAB_RECLAIM_ACCOUNT)) >>>>> + continue; >>>>> + >>>>> + memset(&sinfo, 0, sizeof(sinfo)); >>>> >>>> why do you zero out the structure. All the fields you are printing are >>>> filled out in get_slabinfo. >>> >>> No special reason, just wipe out the potential stale data on the stack. >> >> Do not add code that has no meaning. The OOM killer is a slow path but >> that doesn't mean we should throw spare cycles out of the window. > > With this fixed and the compile fix [1] folded, feel free to add my > Acked-by: Michal Hocko <mhocko@suse.com> > > [1] http://lkml.kernel.org/r/1507492085-42264-1-git-send-email-yang.s@alibaba-inc.com
Did some more thorough test and took the code a little deeper, it sounds !CONFIG_SLOB is not enough. Some data structure and functions depends on CONFIG_SLUB_DEBUG, i.e. kmem_cache_node->total_objects and node_nr_objs(), which are essential of get_slabinfo().
So, I'm supposed it makes more sense to protect the related slab stats code and the unreclaimable slabinfo dump with CONFIG_SLAB || CONFIG_SLUB_DEBUG.
Thanks, Yang
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