Message-ID: <63255554-cc9c-44f4-9977-76d5d3a3f677@kernel.org>
Date: Fri, 17 May 2024 11:49:35 +0800
From: Chao Yu <chao@...nel.org>
To: 孙士杰 <sunshijie@...omi.com>,
 sunshijie <sunshijie@...omi.corp-partner.google.com>,
 "jaegeuk@...nel.org" <jaegeuk@...nel.org>,
 "linux-f2fs-devel@...ts.sourceforge.net"
 <linux-f2fs-devel@...ts.sourceforge.net>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: 答复: [External Mail][PATCH] f2fs: fix panic in f2fs_put_super

On 2024/5/16 18:15, 孙士杰 wrote:
> I didn't get it, if there is no cp_err, f2fs_write_checkpoint() in
> f2fs_put_super() will flush all dirty pages of node_inode, if there is
> cp_err, below flow will keep all dirty pages being truncated, and
> there is sanity check on all types of dirty pages.
> 
> ===》
> I understand what you mean, so is it better to modify in this way? Please help to check, thank you

Hi, let's figure out the root cause first?

Thanks,

> 
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> *发件人:* sunshijie <sunshijie@...omi.corp-partner.google.com>
> *发送时间:* 2024年5月16日 18:13:38
> *收件人:* jaegeuk@...nel.org; chao@...nel.org; linux-f2fs-devel@...ts.sourceforge.net; linux-kernel@...r.kernel.org
> *抄送:* 孙士杰
> *主题:* [External Mail][PATCH] f2fs: fix panic in f2fs_put_super
> [外部邮件] 此邮件来源于小米公司外部，请谨慎处理。若对邮件安全性存疑，请将邮件转发给misec@...omi.com进行反馈
> 
> When thread A calls kill_f2fs_super, Thread A first executes the code sbi->node_inode = NULL;
> Then thread A may submit a bio to the function iput(sbi->meta_inode);
> Then thread A enters the process D state,
> Now that the bio submitted by thread A is complete, it calls f2fs_write_end_io and may trigger null-ptr-deref in NODE_MAPPING.
> 
> Thread A                                          IRQ context
> - f2fs_put_super
>   - sbi->node_inode = NULL;
>   - iput(sbi->meta_inode);
>    - iput_final
>     - write_inode_now
>      - writeback_single_inode
>       - __writeback_single_inode
>        - filemap_fdatawait
>         - filemap_fdatawait_range
>          - __kcfi_typeid_free_transhuge_page
>           - __filemap_fdatawait_range
>            - wait_on_page_writeback
>             - folio_wait_writeback
>              - folio_wait_bit
>               - folio_wait_bit_common
>                - io_schedule
> 
>                                                    - __handle_irq_event_percpu
>                                                     - ufs_qcom_mcq_esi_handler
>                                                      - ufshcd_mcq_poll_cqe_nolock
>                                                       - ufshcd_compl_one_cqe
>                                                        - scsi_done
>                                                         - scsi_done_internal
>                                                          - blk_mq_complete_request
>                                                           - scsi_complete
>                                                            - scsi_finish_command
>                                                             - scsi_io_completion
>                                                              - scsi_end_request
>                                                               - blk_update_request
>                                                                - bio_endio
>                                                                 - f2fs_write_end_io
>                                                                  - NODE_MAPPING(sbi)
> 
> Signed-off-by: sunshijie <sunshijie@...omi.com>
> ---
>   fs/f2fs/super.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index adffc9b80a9c..62d4f229f601 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1642,9 +1642,9 @@ static void f2fs_put_super(struct super_block *sb)
>          f2fs_destroy_compress_inode(sbi);
> 
>          iput(sbi->node_inode);
> -       sbi->node_inode = NULL;
> -
>          iput(sbi->meta_inode);
> +
> +       sbi->node_inode = NULL;
>          sbi->meta_inode = NULL;
> 
>          mutex_unlock(&sbi->umount_mutex);
> --
> 2.34.1
> 
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