linux-kernel - Re: [PATCH v3 1/4] fs/dcache: Fix incorrect nr_dentry_unused accounting in shrink_dcache

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Message-ID: <538489aa-d021-5662-7a46-d358f8770054@redhat.com>
Date:   Wed, 12 Sep 2018 11:41:52 -0400
From:   Waiman Long <longman@...hat.com>
To:     Dave Chinner <david@...morbit.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-doc@...r.kernel.org, "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>,
        "Paul E. 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>,
        Michal Hocko <mhocko@...nel.org>
Subject: Re: [PATCH v3 1/4] fs/dcache: Fix incorrect nr_dentry_unused
 accounting in shrink_dcache_sb()

On 09/11/2018 06:02 PM, Dave Chinner wrote:
> On Tue, Sep 11, 2018 at 03:18:23PM -0400, Waiman Long wrote:
>> The nr_dentry_unused per-cpu counter tracks dentries in both the
>> LRU lists and the shrink lists where the DCACHE_LRU_LIST bit is set.
>> The shrink_dcache_sb() function moves dentries from the LRU list to a
>> shrink list and subtracts the dentry count from nr_dentry_unused. This
>> is incorrect as the nr_dentry_unused count Will also be decremented in
>> shrink_dentry_list() via d_shrink_del(). To fix this double decrement,
>> the decrement in the shrink_dcache_sb() function is taken out.
>>
>> Fixes: 4e717f5c1083 ("list_lru: remove special case function list_lru_dispose_all."
>>
>> Signed-off-by: Waiman Long <longman@...hat.com>
> Please add a stable tag for this.
>
> Otherwise looks fine.
>
> Reviewed-by: Dave Chinner <dchinner@...hat.com>
>
I will add the cc:stable tag.

Cheers,
Longman