6.15-stable review patch. If anyone has any objections, please let me know.
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From: John Garry john.g.garry@oracle.com
[ Upstream commit dafeaf2c03e71255438ffe5a341d94d180e6c88e ]
When PCI_IRQ_AFFINITY is set for calling pci_alloc_irq_vectors(), it means interrupts are spread around the available CPUs. It also means that the interrupts become managed, which means that an interrupt is shutdown when all the CPUs in the interrupt affinity mask go offline.
Using managed interrupts in this way means that we should ensure that completions should not occur on HW queues where the associated interrupt is shutdown. This is typically achieved by ensuring only CPUs which are online can generate IO completion traffic to the HW queue which they are mapped to (so that they can also serve completion interrupts for that HW queue).
The problem in the driver is that a CPU can generate completions to a HW queue whose interrupt may be shutdown, as the CPUs in the HW queue interrupt affinity mask may be offline. This can cause IOs to never complete and hang the system. The driver maintains its own CPU <-> HW queue mapping for submissions, see aac_fib_vector_assign(), but this does not reflect the CPU <-> HW queue interrupt affinity mapping.
Commit 9dc704dcc09e ("scsi: aacraid: Reply queue mapping to CPUs based on IRQ affinity") tried to remedy this issue may mapping CPUs properly to HW queue interrupts. However this was later reverted in commit c5becf57dd56 ("Revert "scsi: aacraid: Reply queue mapping to CPUs based on IRQ affinity") - it seems that there were other reports of hangs. I guess that this was due to some implementation issue in the original commit or maybe a HW issue.
Fix the very original hang by just not using managed interrupts by not setting PCI_IRQ_AFFINITY. In this way, all CPUs will be in each HW queue affinity mask, so should not create completion problems if any CPUs go offline.
Signed-off-by: John Garry john.g.garry@oracle.com Link: https://lore.kernel.org/r/20250715111535.499853-1-john.g.garry@oracle.com Closes: https://lore.kernel.org/linux-scsi/20250618192427.3845724-1-jmeneghi@redhat.... Reviewed-by: John Meneghini jmeneghi@redhat.com Tested-by: John Meneghini jmeneghi@redhat.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/aacraid/comminit.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/scsi/aacraid/comminit.c b/drivers/scsi/aacraid/comminit.c index 28cf18955a08..726c8531b7d3 100644 --- a/drivers/scsi/aacraid/comminit.c +++ b/drivers/scsi/aacraid/comminit.c @@ -481,8 +481,7 @@ void aac_define_int_mode(struct aac_dev *dev) pci_find_capability(dev->pdev, PCI_CAP_ID_MSIX)) { min_msix = 2; i = pci_alloc_irq_vectors(dev->pdev, - min_msix, msi_count, - PCI_IRQ_MSIX | PCI_IRQ_AFFINITY); + min_msix, msi_count, PCI_IRQ_MSIX); if (i > 0) { dev->msi_enabled = 1; msi_count = i;