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Zhiqiang Liu authored
In brd_init func, rd_nr num of brd_device are firstly allocated and add in brd_devices, then brd_devices are traversed to add each brd_device by calling add_disk func. When allocating brd_device, the disk->first_minor is set to i * max_part, if rd_nr * max_part is larger than MINORMASK, two different brd_device may have the same devt, then only one of them can be successfully added. when rmmod brd.ko, it will cause oops when calling brd_exit. Follow those steps: # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576 # rmmod brd then, the oops will appear. Oops log: [ 726.613722] Call trace: [ 726.614175] kernfs_find_ns+0x24/0x130 [ 726.614852] kernfs_find_and_get_ns+0x44/0x68 [ 726.615749] sysfs_remove_group+0x38/0xb0 [ 726.616520] blk_trace_remove_sysfs+0x1c/0x28 [ 726.617320] blk_unregister_queue+0x98/0x100 [ 726.618105] del_gendisk+0x144/0x2b8 [ 726.618759] brd_exit+0x68/0x560 [brd] [ 726.619501] __arm64_sys_delete_module+0x19c/0x2a0 [ 726.620384] el0_svc_common+0x78/0x130 [ 726.621057] el0_svc_handler+0x38/0x78 [ 726.621738] el0_svc+0x8/0xc [ 726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260) Here, we add brd_check_and_reset_par func to check and limit max_part par. -- V5->V6: - remove useless code V4->V5:(suggested by Ming Lei) - make sure max_part is not larger than DISK_MAX_PARTS V3->V4:(suggested by Ming Lei) - remove useless change - add one limit of max_part V2->V3: (suggested by Ming Lei) - clear .minors when running out of consecutive minor space in brd_alloc - remove limit of rd_nr V1->V2: - add more checks in brd_check_par_valid as suggested by Ming Lei. Signed-off-by:
Zhiqiang Liu <liuzhiqiang26@huawei.com> Reviewed-by:
Bob Liu <bob.liu@oracle.com> Reviewed-by:
Ming Lei <ming.lei@redhat.com> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
c8ab4225