On Wed, Sep 20, 2023 at 12:13:25PM -0700, Kyle Zeng wrote: > On Wed, Sep 20, 2023 at 10:01:55AM -0700, Florian Fainelli wrote: > > On 9/20/23 08:18, Guenter Roeck wrote: > > > On 9/20/23 01:11, Greg Kroah-Hartman wrote: > > > > On Tue, Sep 19, 2023 at 09:57:25PM -0700, Guenter Roeck wrote: > > > > > On 9/17/23 12:07, Greg Kroah-Hartman wrote: > > > > > > This is the start of the stable review cycle for the 5.10.195 release. > > > > > > There are 406 patches in this series, all will be posted as a response > > > > > > to this one. If anyone has any issues with these being applied, please > > > > > > let me know. > > > > > > > > > > > > Responses should be made by Tue, 19 Sep 2023 19:10:04 +0000. > > > > > > Anything received after that time might be too late. > > > > > > > > > > > > > > > > chromeos-5.10 locks up in configfs_lookup() after the merge of > > > > > v5.10.195. > > > > > > > > > > I am a bit puzzled because I see > > > > > > > > > > c709c7ca020a configfs: fix a race in configfs_lookup() > > > > > > > > > > in v5.10.195 but not in the list of commits below. I guess I must be > > > > > missing something. > > > > > > > > It was part of the big patchset, it was posted here: > > > > https://lore.kernel.org/r/20230917191101.511939651@xxxxxxxxxxxxxxxxxxx > > > > > > > > Not hidden at all :) > > > > > > > > and was submitted here: > > > > https://lore.kernel.org/r/ZPOZFHHA0abVmGx+@westworld > > > > > > > > > Either case, the code now looks as follows. > > > > > > > > > > configfs_lookup() > > > > > { > > > > > ... > > > > > spin_lock(&configfs_dirent_lock); > > > > > ... > > > > > err = configfs_attach_attr(sd, dentry); > > > > > ... > > > > > spin_unlock(&configfs_dirent_lock); > > > > > ... > > > > > } > > > > > > > > > > and > > > > > > > > > > configfs_attach_attr(...) > > > > > { > > > > > ... > > > > > spin_lock(&configfs_dirent_lock); > > > > > ... > > > > > } > > > > > > > > > > which unless it is way too late here and I really need to go to sleep > > > > > just won't work. > > > > > > > > Kyle, you did the backport, any comments? > > > > > > > > > > After a good night sleep, the code still looks wrong to me. Reverting > > > the offending patch in chromeos-5.10 solved the problem there. > > > That makes me suspect that no one actually tests configfs. > > > > Humm indeed, looking at our testing we don't have our USB devices being > > tested which would exercise configfs since we switch the USB device between > > different configurations (mass storage, serial, networking etc.). Let me see > > about adding that so we get some coverage. > > -- > > Florian > > > > Sorry for the wrong patch. My intention was to backport c42dd069be8dfc9b2239a5c89e73bbd08ab35de0 > to v5.10 to avoid a race condition triggered in my test. I tested the > patch with my PoC program and made sure it won't trigger the crash. But > I didn't notice that it could hang the kernel. > I sincerely apologize for the mistake. > > My new proposed patch backports both > c42dd069be8dfc9b2239a5c89e73bbd08ab35de0 and d07f132a225c013e59aa77f514ad9211ecab82ee. > I made sure it does not trigger the race condition anymore. > Can anyone having access to more comprehensive tests please check whether it works? > > Also, I'm not sure whether it is OK or how to backport two patches in > one patch. Please advise on how to do it properly. Please backport them both individually, do not merge them together. I'll go revert the current change now and push out a release with it so that it fixes users of this kernel tree. thanks, greg k-h
