Messages in this thread | | | Date | Mon, 7 Jan 2019 11:25:08 +0100 | From | Boris Brezillon <> | Subject | Re: [LKP] [mtd] c4dfa25ab3: kernel_BUG_at_fs/sysfs/file.c |
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Hello Linus,
On Wed, 2 Jan 2019 11:53:34 -0800 Linus Torvalds <torvalds@linux-foundation.org> wrote:
> Hmm.. > > Adding a few more mtd people to the cc.
Sorry for the late reply, I don't have access to my @bootlin.com address anymore and it took me some time to realize you had replied to this bug report.
> > On Tue, Jan 1, 2019 at 4:57 PM kernel test robot <rong.a.chen@intel.com> wrote: > > > > FYI, we noticed the following commit (built with gcc-7): > > > > commit: c4dfa25ab307a277eafa7067cd927fbe4d9be4ba ("mtd: add support for reading MTD devices via the nvmem API") > > > > [ 81.780248] kernel BUG at fs/sysfs/file.c:328! > > [ 81.781914] Call Trace: > > [ 81.781914] sysfs_create_files+0x60/0x180 > > [ 81.781914] mtd_add_partition_attrs+0x14/0x30 > > [ 81.781914] add_mtd_partitions+0x11f/0x260 > > [ 81.781914] mtd_device_parse_register+0x38d/0x4c0 > > [ 81.781914] ns_init_module+0x1033/0x117d > > [ 81.781914] do_one_initcall+0x18f/0x39e > > [ 81.781914] kernel_init_freeable+0x2b4/0x353 > > [ 81.781914] kernel_init+0xa/0x120 > > This actually looks like a very old bug, just exposed by a new error case. > > In particular, the mtd code seems to do this in mtd_add_partition(): > > int ret = 0; > ... > add_mtd_device(&new->mtd); > > mtd_add_partition_attrs(new); > > return ret; > > where 'ret' is actually never set to anything but that initial zero. > > And in fact, it looks like it never was used. > > I _think_ that what's going on is that "add_mtd_device()" historically > never really failed (although it *can* fail), and then > mtd_add_partition_attrs() is called on something that doesn't really > exist. > > It looks like the error handling for the add_mtd_device() case nmever > actually existed, and now the nvmem patch makes that fail in the > test-case, and the lack of error handling is exposed. > > There is another call-site of add_mtd_device() (in > add_mtd_partitions() - same pattern, notice the "s" at the end of the > function name) that also lacks the error handling.
Yep, I fixed the root cause of the crash here [1] and plan to queue the patch to the mtd/fixes branch soon.
Regards,
Boris
[1]http://patchwork.ozlabs.org/patch/1020008
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