[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <9b149dd9-1617-9af4-4252-6d0df01f93b1@bytedance.com>
Date: Tue, 25 Jul 2023 11:01:06 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: akpm@...ux-foundation.org, david@...morbit.com, tkhai@...ru,
vbabka@...e.cz, roman.gushchin@...ux.dev, djwong@...nel.org,
brauner@...nel.org, paulmck@...nel.org, tytso@....edu,
steven.price@....com, cel@...nel.org, senozhatsky@...omium.org,
yujie.liu@...el.com, gregkh@...uxfoundation.org,
muchun.song@...ux.dev, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, x86@...nel.org, kvm@...r.kernel.org,
xen-devel@...ts.xenproject.org, linux-erofs@...ts.ozlabs.org,
linux-f2fs-devel@...ts.sourceforge.net, cluster-devel@...hat.com,
linux-nfs@...r.kernel.org, linux-mtd@...ts.infradead.org,
rcu@...r.kernel.org, netdev@...r.kernel.org,
dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
dm-devel@...hat.com, linux-raid@...r.kernel.org,
linux-bcache@...r.kernel.org,
virtualization@...ts.linux-foundation.org,
linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-xfs@...r.kernel.org, linux-btrfs@...r.kernel.org
Subject: Re: [PATCH v2 03/47] mm: shrinker: add infrastructure for dynamically
allocating shrinker
Hi Peter,
On 2023/7/24 20:25, Peter Zijlstra wrote:
> On Mon, Jul 24, 2023 at 05:43:10PM +0800, Qi Zheng wrote:
>
>> +void shrinker_unregister(struct shrinker *shrinker)
>> +{
>> + struct dentry *debugfs_entry;
>> + int debugfs_id;
>> +
>> + if (!shrinker || !(shrinker->flags & SHRINKER_REGISTERED))
>> + return;
>> +
>> + down_write(&shrinker_rwsem);
>> + list_del(&shrinker->list);
>> + shrinker->flags &= ~SHRINKER_REGISTERED;
>> + if (shrinker->flags & SHRINKER_MEMCG_AWARE)
>> + unregister_memcg_shrinker(shrinker);
>> + debugfs_entry = shrinker_debugfs_detach(shrinker, &debugfs_id);
>> + up_write(&shrinker_rwsem);
>> +
>> + shrinker_debugfs_remove(debugfs_entry, debugfs_id);
>
> Should there not be an rcu_barrier() right about here?
The shrinker_debugfs_remove() will wait for debugfs_file_put() to
return, so when running here, all shrinker debugfs operations have
been completed. And the slab shrink will hold the read lock of
shrinker_rwsem to traverse the shrinker_list, so when we hold the
write lock of shrinker_rwsem to delete the shrinker from the
shrinker_list, the shrinker will not be executed again.
So I think there is no need to add a rcu_barrier() here. Please let
me know if I missed something.
Thanks,
Qi
>
>> +
>> + kfree(shrinker->nr_deferred);
>> + shrinker->nr_deferred = NULL;
>> +
>> + kfree(shrinker);
>> +}
>> +EXPORT_SYMBOL(shrinker_unregister);
>
Powered by blists - more mailing lists