linux-kernel - Re: [PATCH] slub: Don't panic for memcg kmem cache creation failure

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Message-ID: <e7ce6ea7-50fc-78ad-1394-4da11cba7ad3@intel.com>
Date:   Thu, 20 Jun 2019 07:51:50 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Shakeel Butt <shakeelb@...gle.com>,
        Michal Hocko <mhocko@...nel.org>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Christoph Lameter <cl@...ux.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <guro@...com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Cgroups <cgroups@...r.kernel.org>, Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] slub: Don't panic for memcg kmem cache creation failure

On 6/20/19 7:44 AM, Shakeel Butt wrote:
>> I am wondering whether SLAB_PANIC makes sense in general though. Why is
>> it any different from any other essential early allocations? We tend to
>> not care about allocation failures for those on bases that the system
>> must be in a broken state to fail that early already. Do you think it is
>> time to remove SLAB_PANIC altogether?
>>
> That would need some investigation into the history of SLAB_PANIC. I
> will look into it.

I think it still makes sense for things like the vma, filp, dentry
caches.  If we don't
have those, we can't even execve("/sbin/init") so we shouldn't even bother
continuing to boot.

Maybe we should turn off SLAB_PANIC behavior after boot.  We don't want
a silly driver or filesystem module that's creating slabs to be causing
panic()s.