Hello Michael, On Tue, Aug 13, 2024 at 10:32:36PM +1000, Michael Ellerman wrote: > Niklas Cassel <cassel@xxxxxxxxxx> writes: > > Hello Jonáš, Kolbjørn, > > > > thank you for the report. > > > > On Tue, Aug 13, 2024 at 07:49:34AM +0200, Jonáš Vidra wrote: > >> On Tue 13. Aug 2024 0:32:37 CEST, Kolbjørn Barmen wrote: > >> > Ever since 6.10, my macmini G4 behaved unstable when dealing with lots of > >> > I/O activity, such as sync'ing of Gentoo portage tree, unpacking kernel > >> > source tarball, building large software packages (or kernel) etc. > >> > > >> > After a bit of testing, and patient kernel rebuilding (while crashing) I > >> > found the cuplit to be this commit/change > >> > > >> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/diff/?id=09fe2bfa6b83f865126ce3964744863f69a4a030 > >> > >> I've been able to reproduce this pata_macio bug on a desktop PowerMac G4 > >> with the 6.10.3 kernel version. Reverting the linked change > >> ("ata: pata_macio: Fix max_segment_size with PAGE_SIZE == 64K") makes > >> the errors go away. > > > > Michael, as the author of the this commit, could you please look into > > this issue? > > I can. My commit was really just working around the warning in the SCSI > core which appeared after afd53a3d8528, it was supposed to just fix the > warning without changing behaviour. Though obviously it did for 4KB > PAGE_SIZE kernels. > > I don't have easy access to my mac-mini so it would be helpful if you > can test changes Jonáš and/or Kolbjørn. > > > We could revert your patch, which appears to work for some users, > > but that would again break setups with PAGE_SIZE == 64K. > > (I assume that Jonáš and Kolbjørn are not building with PAGE_SIZE == 64K.) > > Yes they are using 4K, it says so in the oops. > > >> ------------[ cut here ]------------ > >> kernel BUG at drivers/ata/pata_macio.c:544! > > > > https://github.com/torvalds/linux/blob/v6.11-rc3/drivers/ata/pata_macio.c#L544 > > > > It seems that the > > while (sg_len) loop does not play nice with the new .max_segment_size. > > Right, but only for 4KB kernels for some reason. Is there some limit > elsewhere that prevents the bug tripping on 64KB kernels, or is it just > luck that no one has hit it? Have your tried running fio (flexible I/O tester), with reads with a very large block sizes? I would be surprised if it isn't possible to trigger the same bug with 64K page size. max segment size = 64K MAX_DCMDS = 256 256 * 64K = 16 MiB What happens if you run fio with a 16 MiB blocksize? Something like: $ sudo fio --name=test --filename=/dev/sdX --direct=1 --runtime=60 --ioengine=io_uring --rw=read --iodepth=4 --bs=16M Kind regards, Niklas
