When thread A calls kill_f2fs_super, thread A may submit a bio to the function iput(sbi->node_inode); Then thread A enters the process D state, and thread B may also call kill_f2fs_super and execute the code sbi->node_inode = NULL; 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 Thread B IRQ context - f2fs_put_super - iput(sbi->node_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 - f2fs_put_super - sbi->node_inode = NULL - __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 <sunshi...@xiaomi.com> --- fs/f2fs/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index a4bc26dfdb1a..adffc9b80a9c 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -1618,7 +1618,6 @@ static void f2fs_put_super(struct super_block *sb) f2fs_release_ino_entry(sbi, true); f2fs_leave_shrinker(sbi); - mutex_unlock(&sbi->umount_mutex); /* our cp_error case, we can wait for any writeback page */ f2fs_flush_merged_writes(sbi); @@ -1648,6 +1647,8 @@ static void f2fs_put_super(struct super_block *sb) iput(sbi->meta_inode); sbi->meta_inode = NULL; + mutex_unlock(&sbi->umount_mutex); + /* * iput() can update stat information, if f2fs_write_checkpoint() * above failed with error. -- 2.34.1 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel