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: Tue, 26 Oct 2021 10:18:11 +0800 [thread overview]
Message-ID: <209361bb-9e15-ebaf-2ff8-5846d5bfbbc2@huawei.com> (raw)
In-Reply-To: <YXAL7K88XGWXckWe@kroah.com>
在 2021/10/20 20:30, Greg KH 写道:
> On Wed, Oct 13, 2021 at 06:49:06PM +0800, chenxiaosong (A) wrote:
>> 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?
>
> That would be a better idea, but still, this is not obvious that this is
> the correct fix at all...
> .
>
Why is this patch not correct? Can you tell me more about it? Thanks.
next prev parent reply other threads:[~2021-10-26 2:18 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)
2021-10-20 12:30 ` Greg KH
2021-10-26 2:18 ` chenxiaosong (A) [this message]
2021-10-26 5:45 ` Greg KH
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=209361bb-9e15-ebaf-2ff8-5846d5bfbbc2@huawei.com \
--to=chenxiaosong2@huawei.com \
--cc=dhowells@redhat.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@vger.kernel.org \
--cc=viro@zeniv.linux.org.uk \
--cc=yi.zhang@huawei.com \
--cc=yukuai3@huawei.com \
--cc=zhangxiaoxu5@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).