On 2020/2/4 16:52, Ming Lei wrote: > 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> Sorry for missing that. I will remove these in v6 patch. Thanks for your patience.
