linux-kernel - Re: [RFC PATCH 1/2] mm, oom: Introduce bpf_select

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 7 Aug 2023 10:21:09 +0800
From:   Chuyi Zhou <zhouchuyi@...edance.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     hannes@...xchg.org, roman.gushchin@...ux.dev, ast@...nel.org,
        daniel@...earbox.net, andrii@...nel.org, muchun.song@...ux.dev,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        wuyun.abel@...edance.com, robin.lu@...edance.com
Subject: Re: [RFC PATCH 1/2] mm, oom: Introduce bpf_select_task



在 2023/8/4 21:34, Michal Hocko 写道:
> On Fri 04-08-23 21:15:57, Chuyi Zhou wrote:
> [...]
>>> +	switch (bpf_oom_evaluate_task(task, oc, &points)) {
>>> +		case -EOPNOTSUPP: break; /* No BPF policy */
>>> +		case -EBUSY: goto abort; /* abort search process */
>>> +		case 0: goto next; /* ignore process */
>>> +		default: goto select; /* note the task */
>>> +	}
>>
>> Why we need to change the *points* value if we do not care about oom_badness
>> ? Is it used to record some state? If so, we could record it through bpf
>> map.
> 
> Strictly speaking we do not need to. That would require BPF to keep the
> state internally. Many will do I suppose but we have to keep track of
> the victim so that the oom killer knows what to kill so I thought that
> it doesn't hurt to keep track of an abstract concept of points as well.
> If you think this is not needed then oc->points could be always 0 for
> bpf selected victims. The value is not used anyway in the proposed
> scheme.
> 
> Btw. we will need another hook or metadata for the reporting side of
> things. Generally dump_header() to know what has been the selection
> policy.
> 
OK. Maybe a integer like policy_type is enough to distinguish different 
policies and the default method is zero. Or we can let BPF return a 
string like policy_name.

Which one should I start implementing in next version? Do you have a 
better idea?

Thanks.