b1d2dc5659
Currenly blk_get_backing_dev_info() is not safe to be called when the block device is not open as bdev->bd_disk is NULL in that case. However inode_to_bdi() uses this function and may be call called from flusher worker or other writeback related functions without bdev being open which leads to crashes such as: [113031.075540] Unable to handle kernel paging request for data at address 0x00000000 [113031.075614] Faulting instruction address: 0xc0000000003692e0 0:mon> t [c0000000fb65f900] c00000000036cb6c writeback_sb_inodes+0x30c/0x590 [c0000000fb65fa10] c00000000036ced4 __writeback_inodes_wb+0xe4/0x150 [c0000000fb65fa70] c00000000036d33c wb_writeback+0x30c/0x450 [c0000000fb65fb40] c00000000036e198 wb_workfn+0x268/0x580 [c0000000fb65fc50] c0000000000f3470 process_one_work+0x1e0/0x590 [c0000000fb65fce0] c0000000000f38c8 worker_thread+0xa8/0x660 [c0000000fb65fd80] c0000000000fc4b0 kthread+0x110/0x130 [c0000000fb65fe30] c0000000000098f0 ret_from_kernel_thread+0x5c/0x6c Signed-off-by: Jens Axboe <axboe@fb.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.