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From: Xiubo Li <xiubli@redhat.com>
To: Jeff Layton <jlayton@kernel.org>
Cc: idryomov@gmail.com, pdonnell@redhat.com, ceph-devel@vger.kernel.org
Subject: Re: [PATCH v2] ceph: correctly release memory from capsnap
Date: Wed, 18 Aug 2021 09:28:48 +0800	[thread overview]
Message-ID: <a45660db-0125-ffa7-6c94-345ecafab075@redhat.com> (raw)
In-Reply-To: <25dd85fdb777f9b260392ceeda41fc5e62018ddd.camel@kernel.org>


On 8/17/21 10:03 PM, Jeff Layton wrote:
> On Tue, 2021-08-17 at 20:35 +0800, xiubli@redhat.com wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> When force umounting, it will try to remove all the session caps.
>> If there has any capsnap is in the flushing list, the remove session
>> caps callback will try to release the capsnap->flush_cap memory to
>> "ceph_cap_flush_cachep" slab cache, while which is allocated from
>> kmalloc-256 slab cache.
>>
>> At the same time switch to list_del_init() because just in case the
>> force umount has removed it from the lists and the
>> handle_cap_flushsnap_ack() comes then the seconds list_del_init()
>> won't crash the kernel.
>>
>> URL: https://tracker.ceph.com/issues/52283
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>>
>> - Only to resolve the crash issue.
>> - s/list_del/list_del_init/
>>
>>
>>   fs/ceph/caps.c       | 18 ++++++++++++++----
>>   fs/ceph/mds_client.c |  7 ++++---
>>   2 files changed, 18 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
>> index 990258cbd836..4ee0ef87130a 100644
>> --- a/fs/ceph/caps.c
>> +++ b/fs/ceph/caps.c
>> @@ -1667,7 +1667,16 @@ int __ceph_mark_dirty_caps(struct ceph_inode_info *ci, int mask,
>>   
>>   struct ceph_cap_flush *ceph_alloc_cap_flush(void)
>>   {
>> -	return kmem_cache_alloc(ceph_cap_flush_cachep, GFP_KERNEL);
>> +	struct ceph_cap_flush *cf;
>> +
>> +	cf = kmem_cache_alloc(ceph_cap_flush_cachep, GFP_KERNEL);
>> +	/*
>> +	 * caps == 0 always means for the capsnap
>> +	 * caps > 0 means dirty caps being flushed
>> +	 * caps == -1 means preallocated, not used yet
>> +	 */
>> +	cf->caps = -1;
>> +	return cf;
>>   }
>>   
>>   void ceph_free_cap_flush(struct ceph_cap_flush *cf)
>> @@ -1704,14 +1713,14 @@ static bool __finish_cap_flush(struct ceph_mds_client *mdsc,
>>   			prev->wake = true;
>>   			wake = false;
>>   		}
>> -		list_del(&cf->g_list);
>> +		list_del_init(&cf->g_list);
>>   	} else if (ci) {
>>   		if (wake && cf->i_list.prev != &ci->i_cap_flush_list) {
>>   			prev = list_prev_entry(cf, i_list);
>>   			prev->wake = true;
>>   			wake = false;
>>   		}
>> -		list_del(&cf->i_list);
>> +		list_del_init(&cf->i_list);
>>   	} else {
>>   		BUG_ON(1);
>>   	}
>> @@ -3398,7 +3407,8 @@ static void handle_cap_flush_ack(struct inode *inode, u64 flush_tid,
>>   		cf = list_first_entry(&to_remove,
>>   				      struct ceph_cap_flush, i_list);
>>   		list_del(&cf->i_list);
>> -		ceph_free_cap_flush(cf);
>> +		if (cf->caps)
>> +			ceph_free_cap_flush(cf);
>>   	}
>>   
>>   	if (wake_ci)
>> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
>> index 2c3d762c7973..dc30f56115fa 100644
>> --- a/fs/ceph/mds_client.c
>> +++ b/fs/ceph/mds_client.c
>> @@ -1226,7 +1226,7 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
>>   		spin_lock(&mdsc->cap_dirty_lock);
>>   
>>   		list_for_each_entry(cf, &to_remove, i_list)
>> -			list_del(&cf->g_list);
>> +			list_del_init(&cf->g_list);
>>   
>>   		if (!list_empty(&ci->i_dirty_item)) {
>>   			pr_warn_ratelimited(
>> @@ -1266,8 +1266,9 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
>>   		struct ceph_cap_flush *cf;
>>   		cf = list_first_entry(&to_remove,
>>   				      struct ceph_cap_flush, i_list);
>> -		list_del(&cf->i_list);
>> -		ceph_free_cap_flush(cf);
>> +		list_del_init(&cf->i_list);
>> +		if (cf->caps)
>> +			ceph_free_cap_flush(cf);
>>   	}
>>   
>>   	wake_up_all(&ci->i_cap_wq);
> This patch doesn't seem to apply to the current testing branch. Is it
> against an older tree?

I was trying to test the old tags and forgot to switch it back.

Have send out the V3 to fix it.

Thanks



      reply	other threads:[~2021-08-18  1:28 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-17 12:35 [PATCH v2] ceph: correctly release memory from capsnap xiubli
2021-08-17 14:03 ` Jeff Layton
2021-08-18  1:28   ` Xiubo Li [this message]

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