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  1. 06 May, 2016 2 commits
    • Jon Maxwell's avatar
      cnic: call cp->stop_hw() in cnic_start_hw() on allocation failure · f37bd0cc
      Jon Maxwell authored 
      We recently had a system crash in the cnic module. Vmcore analysis confirmed
that "ip link up" was executed which failed due to an allocation failure
because of memory fragmentation. Futher analysis revealed that the cnic irq
vector was still allocated after the "ip link up" that failed. When
"ip link down" was executed it called free_msi_irqs() which crashed the system
because the cnic irq was still inuse.

PANIC: "kernel BUG at drivers/pci/msi.c:411!"

The code execution was:

cnic_netdev_event()
if (event == NETDEV_UP) {
.
.
       ▹       if (!cnic_start_hw(dev))
cnic_start_hw()
calls cnic_cm_open() which failed with -ENOMEM
cnic_start_hw() then took the err1 path:

err1:↩
       cp->free_resc(dev);↩ <---- frees resources but not irq vector
       pci_dev_put(dev->pcidev);↩
       return err;↩
}↩

This returns control back to cnic_netdev_event() but now the cnic irq vector
is still allocated even although cnic_cm_open() failed. The next
"ip link down" while trigger the crash.

The cnic_start_hw() routine is not handling the allocation failure correctly.
Fix this by checking whether CNIC_DRV_STATE_HANDLES_IRQ flag is set indicating
that the hardware has been started in cnic_start_hw(). If it has then call
cp->stop_hw() which frees the cnic irq vector and cnic resources. Otherwise
just maintain the previous behaviour and free cnic resources.

I reproduced this by injecting an ENOMEM error into cnic_cm_alloc_mem()s return
code.

# ip link set dev enpX down
# ip link set dev enpX up <--- hit's allocation failure
# ip link set dev enpX down <--- crashes here

With this patch I confirmed there was no crash in the reproducer.
Signed-off-by: default avatarJon Maxwell <jmaxwell37@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      f37bd0cc
    • Haggai Abramovsky's avatar
      net/mlx4: Avoid wrong virtual mappings · 73898db0
      Haggai Abramovsky authored 
      The dma_alloc_coherent() function returns a virtual address which can
be used for coherent access to the underlying memory.  On some
architectures, like arm64, undefined behavior results if this memory is
also accessed via virtual mappings that are not coherent.  Because of
their undefined nature, operations like virt_to_page() return garbage
when passed virtual addresses obtained from dma_alloc_coherent().  Any
subsequent mappings via vmap() of the garbage page values are unusable
and result in bad things like bus errors (synchronous aborts in ARM64
speak).

The mlx4 driver contains code that does the equivalent of:
vmap(virt_to_page(dma_alloc_coherent)), this results in an OOPs when the
device is opened.

Prevent Ethernet driver to run this problematic code by forcing it to
allocate contiguous memory. As for the Infiniband driver, at first we
are trying to allocate contiguous memory, but in case of failure roll
back to work with fragmented memory.
Signed-off-by: default avatarHaggai Abramovsky <hagaya@mellanox.com>
Signed-off-by: default avatarYishai Hadas <yishaih@mellanox.com>
Reported-by: default avatarDavid Daney <david.daney@cavium.com>
Tested-by: default avatarSinan Kaya <okaya@codeaurora.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      73898db0
  3. 05 May, 2016 2 commits
  5. 04 May, 2016 36 commits
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