Thank you. I just noticed that this is an out-of-tree module. + Paul Lawrence & Eric Biggers Best Regards, Zhu Faqiang. -----Original Message----- From: Mike Snitzer <snitzer@xxxxxxxxxx> Sent: 2022年2月22日 0:43 To: Faqiang Zhu <faqiang.zhu@xxxxxxx> Cc: hch@xxxxxx; agk@xxxxxxxxxx; dm-devel@xxxxxxxxxx Subject: [EXT] Re: a potential issue for bow_target after "dm: delay registering the gendisk" applied Caution: EXT Email On Mon, Feb 21 2022 at 5:36P -0500, Faqiang Zhu <faqiang.zhu@xxxxxxx> wrote: > Hi Christoph, > > > > Recently when I use kernel5.15 with android, an issue related to bow_target > is found with below log: > > > > [ 8.935429][ T1] kobject_add_internal failed for bow (error: -2 > parent: (null)) > > > > The call trace to the preceding log is as below: > > dm_ctl_ioctl > > -> ctl_ioctl > > -> lookup_ioctl // returns the table_load function pointer > > table_load > > -> populate_table > > -> dm_table_add_target > > -> dm_bow_ctr > > -> kobject_init_and_add > > -> kobject_add_varg > > -> kobject_add_internal > > > > > > Compared to kernel5.10, then I found it's related to below patch. The > gendisk, it's not registered yet, its kobject is not in sysfs, so its child > "bow" kobject cannot be added to the kernel. > > commit 89f871af1b26d98d983cba7ed0e86effa45ba5f8 > > Author: Christoph Hellwig <mailto:hch@xxxxxx> hch@xxxxxx > > Date: Wed Aug 4 11:41:46 2021 +0200 > > > > dm: delay registering the gendisk > > > > > > Is this an issue? if it is, is there any patch to fix it? if it is not, then > what is the right way to use the bow_target in userspace? > It is an issue for this out-of-tree dm-bow target. Likely needs to be fixed by adding a new DM target operation to 'struct target_type' that would get called by DM core at end of dm_setup_md_queue(). Or dm-bow discontinues using sysfs for whatever and convert to using DM messages (with .message) and exposing associated state via .status Mike
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