On Tue, Feb 04, 2020 at 10:44:18AM +0800, Zhiqiang Liu wrote: > > 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. > > -- > 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@xxxxxxxxxx> > Reviewed-by: Bob Liu <bob.liu@xxxxxxxxxx> > --- > drivers/block/brd.c | 27 +++++++++++++++++++++++---- > 1 file changed, 23 insertions(+), 4 deletions(-) > > diff --git a/drivers/block/brd.c b/drivers/block/brd.c > index df8103dd40ac..6b9db3f63cb7 100644 > --- a/drivers/block/brd.c > +++ b/drivers/block/brd.c > @@ -389,11 +389,12 @@ static struct brd_device *brd_alloc(int i) > * is harmless) > */ > blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE); > - disk = brd->brd_disk = alloc_disk(max_part); > + disk = brd->brd_disk = alloc_disk(((i * max_part) & ~MINORMASK) ? > + 0 : max_part); > if (!disk) > goto out_free_queue; > disk->major = RAMDISK_MAJOR; > - disk->first_minor = i * max_part; > + disk->first_minor = i * disk->minors; As I told you, the above change isn't needed, otherwise: Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Thanks, Ming
