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SubjectRe: 答复: [External Mail][PATCH] f2fs: f ix panic in f2fs put super
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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@xiaomi.corp-partner.google.com>
> *发送时间:* 2024年5月16日 18:13:38
> *收件人:* jaegeuk@kernel.org; chao@kernel.org; linux-f2fs-devel@lists.sourceforge.net; linux-kernel@vger.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@xiaomi.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@xiaomi.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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