• Alexey Kardashevskiy's avatar
    powerpc/powernv/ioda2: Allocate TCE table levels on demand for default DMA window · c37c792d
    Alexey Kardashevskiy authored
    We allocate only the first level of multilevel TCE tables for KVM
    already (alloc_userspace_copy==true), and the rest is allocated on demand.
    This is not enabled though for bare metal.
    
    This removes the KVM limitation (implicit, via the alloc_userspace_copy
    parameter) and always allocates just the first level. The on-demand
    allocation of missing levels is already implemented.
    
    As from now on DMA map might happen with disabled interrupts, this
    allocates TCEs with GFP_ATOMIC; otherwise lockdep reports errors 1].
    In practice just a single page is allocated there so chances for failure
    are quite low.
    
    To save time when creating a new clean table, this skips non-allocated
    indirect TCE entries in pnv_tce_free just like we already do in
    the VFIO IOMMU TCE driver.
    
    This changes the default level number from 1 to 2 to reduce the amount
    of memory required for the default 32bit DMA window at the boot time.
    The default window size is up to 2GB which requires 4MB of TCEs which is
    unlikely to be used entirely or at all as most devices these days are
    64bit capable so by switching to 2 levels by default we save 4032KB of
    RAM per a device.
    
    While at this, add __GFP_NOWARN to alloc_pages_node() as the userspace
    can trigger this path via VFIO, see the failure and try creating a table
    again with different parameters which might succeed.
    
    [1]:
    ===
    BUG: sleeping function called from invalid context at mm/page_alloc.c:4596
    in_atomic(): 1, irqs_disabled(): 1, pid: 1038, name: scsi_eh_1
    2 locks held by scsi_eh_1/1038:
     #0: 000000005efd659a (&host->eh_mutex){+.+.}, at: ata_eh_acquire+0x34/0x80
     #1: 0000000006cf56a6 (&(&host->lock)->rlock){....}, at: ata_exec_internal_sg+0xb0/0x5c0
    irq event stamp: 500
    hardirqs last  enabled at (499): [<c000000000cb8a74>] _raw_spin_unlock_irqrestore+0x94/0xd0
    hardirqs last disabled at (500): [<c000000000cb85c4>] _raw_spin_lock_irqsave+0x44/0x120
    softirqs last  enabled at (0): [<c000000000101120>] copy_process.isra.4.part.5+0x640/0x1a80
    softirqs last disabled at (0): [<0000000000000000>] 0x0
    CPU: 73 PID: 1038 Comm: scsi_eh_1 Not tainted 5.2.0-rc6-le_nv2_aikATfstn1-p1 #634
    Call Trace:
    [c000003d064cef50] [c000000000c8e6c4] dump_stack+0xe8/0x164 (unreliable)
    [c000003d064cefa0] [c00000000014ed78] ___might_sleep+0x2f8/0x310
    [c000003d064cf020] [c0000000003ca084] __alloc_pages_nodemask+0x2a4/0x1560
    [c000003d064cf220] [c0000000000c2530] pnv_alloc_tce_level.isra.0+0x90/0x130
    [c000003d064cf290] [c0000000000c2888] pnv_tce+0x128/0x3b0
    [c000003d064cf360] [c0000000000c2c00] pnv_tce_build+0xb0/0xf0
    [c000003d064cf3c0] [c0000000000bbd9c] pnv_ioda2_tce_build+0x3c/0xb0
    [c000003d064cf400] [c00000000004cfe0] ppc_iommu_map_sg+0x210/0x550
    [c000003d064cf510] [c00000000004b7a4] dma_iommu_map_sg+0x74/0xb0
    [c000003d064cf530] [c000000000863944] ata_qc_issue+0x134/0x470
    [c000003d064cf5b0] [c000000000863ec4] ata_exec_internal_sg+0x244/0x5c0
    [c000003d064cf700] [c0000000008642d0] ata_exec_internal+0x90/0xe0
    [c000003d064cf780] [c0000000008650ac] ata_dev_read_id+0x2ec/0x640
    [c000003d064cf8d0] [c000000000878e28] ata_eh_recover+0x948/0x16d0
    [c000003d064cfa10] [c00000000087d760] sata_pmp_error_handler+0x480/0xbf0
    [c000003d064cfbc0] [c000000000884624] ahci_error_handler+0x74/0xe0
    [c000003d064cfbf0] [c000000000879fa8] ata_scsi_port_error_handler+0x2d8/0x7c0
    [c000003d064cfca0] [c00000000087a544] ata_scsi_error+0xb4/0x100
    [c000003d064cfd00] [c000000000802450] scsi_error_handler+0x120/0x510
    [c000003d064cfdb0] [c000000000140c48] kthread+0x1b8/0x1c0
    [c000003d064cfe20] [c00000000000bd8c] ret_from_kernel_thread+0x5c/0x70
    ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
    irq event stamp: 2305
    
    ========================================================
    hardirqs last  enabled at (2305): [<c00000000000e4c8>] fast_exc_return_irq+0x28/0x34
    hardirqs last disabled at (2303): [<c000000000cb9fd0>] __do_softirq+0x4a0/0x654
    WARNING: possible irq lock inversion dependency detected
    5.2.0-rc6-le_nv2_aikATfstn1-p1 #634 Tainted: G        W
    softirqs last  enabled at (2304): [<c000000000cba054>] __do_softirq+0x524/0x654
    softirqs last disabled at (2297): [<c00000000010f278>] irq_exit+0x128/0x180
    --------------------------------------------------------
    swapper/0/0 just changed the state of lock:
    0000000006cf56a6 (&(&host->lock)->rlock){-...}, at: ahci_single_level_irq_intr+0xac/0x120
    but this lock took another, HARDIRQ-unsafe lock in the past:
     (fs_reclaim){+.+.}
    
    and interrupts could create inverse lock ordering between them.
    
    other info that might help us debug this:
     Possible interrupt unsafe locking scenario:
    
           CPU0                    CPU1
           ----                    ----
      lock(fs_reclaim);
                                   local_irq_disable();
                                   lock(&(&host->lock)->rlock);
                                   lock(fs_reclaim);
      <Interrupt>
        lock(&(&host->lock)->rlock);
    
     *** DEADLOCK ***
    
    no locks held by swapper/0/0.
    
    the shortest dependencies between 2nd lock and 1st lock:
     -> (fs_reclaim){+.+.} ops: 167579 {
        HARDIRQ-ON-W at:
                          lock_acquire+0xf8/0x2a0
                          fs_reclaim_acquire.part.23+0x44/0x60
                          kmem_cache_alloc_node_trace+0x80/0x590
                          alloc_desc+0x64/0x270
                          __irq_alloc_descs+0x2e4/0x3a0
                          irq_domain_alloc_descs+0xb0/0x150
                          irq_create_mapping+0x168/0x2c0
                          xics_smp_probe+0x2c/0x98
                          pnv_smp_probe+0x40/0x9c
                          smp_prepare_cpus+0x524/0x6c4
                          kernel_init_freeable+0x1b4/0x650
                          kernel_init+0x2c/0x148
                          ret_from_kernel_thread+0x5c/0x70
        SOFTIRQ-ON-W at:
                          lock_acquire+0xf8/0x2a0
                          fs_reclaim_acquire.part.23+0x44/0x60
                          kmem_cache_alloc_node_trace+0x80/0x590
                          alloc_desc+0x64/0x270
                          __irq_alloc_descs+0x2e4/0x3a0
                          irq_domain_alloc_descs+0xb0/0x150
                          irq_create_mapping+0x168/0x2c0
                          xics_smp_probe+0x2c/0x98
                          pnv_smp_probe+0x40/0x9c
                          smp_prepare_cpus+0x524/0x6c4
                          kernel_init_freeable+0x1b4/0x650
                          kernel_init+0x2c/0x148
                          ret_from_kernel_thread+0x5c/0x70
        INITIAL USE at:
                         lock_acquire+0xf8/0x2a0
                         fs_reclaim_acquire.part.23+0x44/0x60
                         kmem_cache_alloc_node_trace+0x80/0x590
                         alloc_desc+0x64/0x270
                         __irq_alloc_descs+0x2e4/0x3a0
                         irq_domain_alloc_descs+0xb0/0x150
                         irq_create_mapping+0x168/0x2c0
                         xics_smp_probe+0x2c/0x98
                         pnv_smp_probe+0x40/0x9c
                         smp_prepare_cpus+0x524/0x6c4
                         kernel_init_freeable+0x1b4/0x650
                         kernel_init+0x2c/0x148
                         ret_from_kernel_thread+0x5c/0x70
      }
    ===
    Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
    Reviewed-by: default avatarAlistair Popple <alistair@popple.id.au>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/20190718051139.74787-4-aik@ozlabs.ru
    c37c792d
pci.h 7.54 KB