From: "chenxiaosong (A)" <chenxiaosong2@huawei.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: <viro@zeniv.linux.org.uk>, <stable@vger.kernel.org>,
<linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<dhowells@redhat.com>, <yukuai3@huawei.com>,
<yi.zhang@huawei.com>, <zhangxiaoxu5@huawei.com>
Subject: Re: [PATCH 4.19,v2] VFS: Fix fuseblk memory leak caused by mount concurrency
Date: Wed, 13 Oct 2021 18:49:06 +0800 [thread overview]
Message-ID: <860c36c4-3668-1388-66d1-a07d463c2ad9@huawei.com> (raw)
In-Reply-To: <429d87b0-3a53-052a-a304-0afa8d51900d@huawei.com>
在 2021/10/13 18:38, chenxiaosong (A) 写道:
> 在 2021/10/13 18:11, Greg KH 写道:
>> On Wed, Oct 13, 2021 at 05:51:01PM +0800, ChenXiaoSong wrote:
>>> If two processes mount same superblock, memory leak occurs:
>>>
>>> CPU0 | CPU1
>>> do_new_mount | do_new_mount
>>> fs_set_subtype | fs_set_subtype
>>> kstrdup |
>>> | kstrdup
>>> memrory leak |
>>>
>>> Fix this by adding a write lock while calling fs_set_subtype.
>>>
>>> Linus's tree already have refactoring patchset [1], one of them can
>>> fix this bug:
>>> c30da2e981a7 (fuse: convert to use the new mount API)
>>>
>>> Since we did not merge the refactoring patchset in this branch, I
>>> create this patch.
>>>
>>> [1]
>>> https://patchwork.kernel.org/project/linux-fsdevel/patch/20190903113640.7984-3-mszeredi@redhat.com/
>>>
>>>
>>> Fixes: 79c0b2df79eb (add filesystem subtype support)
>>> Cc: David Howells <dhowells@redhat.com>
>>> Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
>>> ---
>>> v1: Can not mount sshfs ([PATCH linux-4.19.y] VFS: Fix fuseblk memory
>>> leak caused by mount concurrency)
>>> v2: Use write lock while writing superblock
>>>
>>> fs/namespace.c | 9 ++++++---
>>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> As you are referring to a fuse-only patch above, why are you trying to
>> resolve this issue in the core namespace code instead?
>>
>> How does fuse have anything to do with this?
>>
>> confused,
>>
>> greg k-h
>> .
>>
>
> Now, only `fuse_fs_type` and `fuseblk_fs_type` has `FS_HAS_SUBTYPE` flag
> in kernel code, but maybe there is a filesystem module(`struct
> file_system_type` has `FS_HAS_SUBTYPE` flag). And only mounting fuseblk
> filesystem(e.g. ntfs) will occur memory leak now.
How about updating the subject as: VFS: Fix memory leak caused by
mounting fs with subtype concurrency?
next prev parent reply other threads:[~2021-10-13 10:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-13 9:51 [PATCH 4.19,v2] VFS: Fix fuseblk memory leak caused by mount concurrency ChenXiaoSong
2021-10-13 10:11 ` Greg KH
2021-10-13 10:38 ` chenxiaosong (A)
2021-10-13 10:49 ` chenxiaosong (A) [this message]
2021-10-20 12:30 ` Greg KH
2021-10-26 2:18 ` chenxiaosong (A)
2021-10-26 5:45 ` Greg KH
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