linux-kernel - Re: [PATCH] shmem: Use ramfs_kill_sb() for kill

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Message-ID: <77fb9677-8d5c-73e0-41d2-6b3c5040053e@huaweicloud.com>
Date:   Thu, 8 Jun 2023 23:35:23 +0200
From:   Roberto Sassu <roberto.sassu@...weicloud.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     hughd@...gle.com, linux-kernel@...r.kernel.org,
        Roberto Sassu <roberto.sassu@...wei.com>,
        stable@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        David Howells <dhowells@...hat.com>
Subject: Re: [PATCH] shmem: Use ramfs_kill_sb() for kill_sb method of
 ramfs-based tmpfs

On 6/7/2023 7:43 PM, Andrew Morton wrote:
> (cc's added)

Ok. Recently, I started to automatize the recipients of the emails with 
a script that takes the output of get_maintainer.pl and takes only the 
maintainer, supporter and reviewer lines. Maybe I should add also 
blamed_fixes.

> On Wed,  7 Jun 2023 18:15:23 +0200 Roberto Sassu <roberto.sassu@...weicloud.com> wrote:
> 
>> From: Roberto Sassu <roberto.sassu@...wei.com>
>>
>> As the ramfs-based tmpfs uses ramfs_init_fs_context() for the
>> init_fs_context method, which allocates fc->s_fs_info, use ramfs_kill_sb()
>> to free it and avoid a memory leak.
>>
>> Cc: stable@...r.kernel.org # v5.4.x
>> Fixes: f32356261d44 ("vfs: Convert ramfs, shmem, tmpfs, devtmpfs, rootfs to use the new mount API")

As I mentioned in the other thread, the correct Fixes tag is:

Fixes: c3b1b1cbf002 ("ramfs: add support for "mode=" mount option")

of course, if it can be modified at this stage.

Thanks

Roberto

>> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
>> ---
>>   fs/ramfs/inode.c      | 2 +-
>>   include/linux/ramfs.h | 1 +
>>   mm/shmem.c            | 2 +-
>>   3 files changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
>> index 5ba580c7883..fef477c7810 100644
>> --- a/fs/ramfs/inode.c
>> +++ b/fs/ramfs/inode.c
>> @@ -278,7 +278,7 @@ int ramfs_init_fs_context(struct fs_context *fc)
>>   	return 0;
>>   }
>>   
>> -static void ramfs_kill_sb(struct super_block *sb)
>> +void ramfs_kill_sb(struct super_block *sb)
>>   {
>>   	kfree(sb->s_fs_info);
>>   	kill_litter_super(sb);
>> diff --git a/include/linux/ramfs.h b/include/linux/ramfs.h
>> index 917528d102c..d506dc63dd4 100644
>> --- a/include/linux/ramfs.h
>> +++ b/include/linux/ramfs.h
>> @@ -7,6 +7,7 @@
>>   struct inode *ramfs_get_inode(struct super_block *sb, const struct inode *dir,
>>   	 umode_t mode, dev_t dev);
>>   extern int ramfs_init_fs_context(struct fs_context *fc);
>> +extern void ramfs_kill_sb(struct super_block *sb);
>>   
>>   #ifdef CONFIG_MMU
>>   static inline int
>> diff --git a/mm/shmem.c b/mm/shmem.c
>> index e40a08c5c6d..74abb97ea55 100644
>> --- a/mm/shmem.c
>> +++ b/mm/shmem.c
>> @@ -4196,7 +4196,7 @@ static struct file_system_type shmem_fs_type = {
>>   	.name		= "tmpfs",
>>   	.init_fs_context = ramfs_init_fs_context,
>>   	.parameters	= ramfs_fs_parameters,
>> -	.kill_sb	= kill_litter_super,
>> +	.kill_sb	= ramfs_kill_sb,
>>   	.fs_flags	= FS_USERNS_MOUNT,
>>   };
>>   
>> -- 
>> 2.25.1