On Tue, 4 Jun 2019 at 17:41, Coly Li <colyli@xxxxxxx> wrote: > > On 2019/6/4 10:59 下午, Coly Li wrote: > > On 2019/6/4 7:00 下午, Bjørn Forsman wrote: > >> Hi all, > >> > >> I get a kernel oops from bcache when writing to > >> /sys/block/bcache0/bcache/writeback_percent and there is no attached > >> cache device. See the oops itself below my signature. > >> > >> This is on Linux 4.19.46. I looked in git and see many commits to > >> bcache lately, but none seem to address this particular issue. > >> > >> Background: I'm writing to .../writeback_percent with > >> systemd-tmpfiles. I'd rather not replace it with a script that figures > >> out whether or not the kernel will oops if writing to the sysfs file > >> -- the kernel should not oops in the first place. > > > > Hi Bjorn, > > > > Thank you for the reporting. I believe this is a case we missed in > > testings. When a bcache device is not attached, it does not make sense > > to update the writeback rate in period by the changing of writeback_percent. > > > > I will post a patch for your testing soon. > > Hi Bjorn, > > Could you please to try this patch ? Hope it may help a bit. Hi Coly, Thanks for the quick patch! I tested it on linux 5.2-rc2 and it indeed fixes the problem. There is one typo in the patch/commit message: s/writebac/writeback/ -- Best regards, Bjørn Forsman
