Messages in this thread | | | Date | Mon, 24 Oct 2022 15:20:43 +0200 | From | Juergen Gross <> | Subject | Re: Report in downstream Debian: mpt3sas broken with xen dom0 with update to 5.10.149 in 5.10.y. |
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On 24.10.22 14:51, James Bottomley wrote: > On Mon, 2022-10-24 at 17:26 +0530, Sreekanth Reddy wrote: >> On Sun, Oct 23, 2022 at 6:57 AM Bart Van Assche <bvanassche@acm.org> >> wrote: >>> On 10/21/22 02:22, Salvatore Bonaccorso wrote: >>>> We got the following report in Debian after an update from >>>> 5.10.140 to >>>> the current 5.10.149. Full quoting below (from >>>> https://bugs.debian.org/1022126). Does this ring some bell about >>>> known >>>> regressions? >>> >>> Only three mpt3sas changes are new in v5.10.149 compared to >>> v5.10.140: >>> $ git log --format=oneline v5.10.140..v5.10.149 >>> 2b9aba0c5d58e141e32bb1bb4c7cd91d19f075b8 scsi: mpt3sas: Fix return >>> value check of dma_get_required_mask() >>> e7fafef9830c4a01e60f76e3860a9bef0262378d scsi: mpt3sas: Force PCIe >>> scatterlist allocations to be within same 4 GB region >>> ea10a652ad2ae2cf3eced6f632a5c98f26727057 scsi: mpt3sas: Fix use- >>> after-free warning >>> >>> Sreekanth and Suganath, can you help with bisecting this issue? For >>> the >>> full report, see also >>> https://lore.kernel.org/linux-scsi/Y1JkuKTjVYrOWbvm@eldamar.lan/. >> >> This issue is getting observed after having the below patch changes, >> 2b9aba0c5d58e141e32bb1bb4c7cd91d19f075b8 scsi: mpt3sas: Fix return >> value check of dma_get_required_mask() >> >> What is happening is that on Xen hypervisor, this >> dma_get_required_mask() API always returns a 32 bit DMA mask. I.e. It >> says that the minimum DMA mask required to access the host memory is >> 32 bit and hence mpt3sas driver is setting the DMA mask to 32bit. > > This sounds entirely correct because the VM is booted with (from the > original debian bug report): > > dom0_mem=4096M,max:4096M dom0_max_vcpus=4 dom0_vcpus_pin > ucode=scan xpti=dom0=false,domu=true gnttab_max_frames=128 > > So it has no memory above 4GB and thus 32 bit addressing is the minimum > required. If you boot a machine with >4GB and Xen still returns a 32 > bit mask here, then we have a Xen problem.
Dom0 is (normally) a PV domain, so the physical memory can be still above 4 GB even with dom0_mem set to 4GB.
But please see my other reply to this thread. I think at least one of the backports is plain wrong.
Juergen [unhandled content-type:application/pgp-keys][unhandled content-type:application/pgp-signature] | |