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@xxxxxxx> 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@xxxxxxxxxxx/.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
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