linux-kernel - Re: [PATCH v5 0/6] fs/dcache: Track & limit # of negative dentries

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Message-ID: <CA+55aFyH6dHw-7R3364dn32J4p7kxT=TqmnuozCn9_Bz-MHhxQ@mail.gmail.com>
Date:   Mon, 2 Jul 2018 12:34:00 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Jan Kara <jack@...e.cz>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Miklos Szeredi <mszeredi@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Larry Woodman <lwoodman@...hat.com>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        "Wangkai (Kevin,C)" <wangkai86@...wei.com>
Subject: Re: [PATCH v5 0/6] fs/dcache: Track & limit # of negative dentries

On Sun, Jul 1, 2018 at 10:52 PM Waiman Long <longman@...hat.com> wrote:
>
> A rogue application can potentially create a large number of negative
> dentries in the system consuming most of the memory available if it
> is not under the direct control of a memory controller that enforce
> kernel memory limit.

I certainly don't mind the patch series, but I would like it to be
accompanied with some actual example numbers, just to make it all a
bit more concrete.

Maybe even performance numbers showing "look, I've filled the dentry
lists with nasty negative dentries, now it's all slower because we
walk those less interesting entries".

              Linus