io-mapping: indicate mapping failure
The !ATOMIC_IOMAP version of io_maping_init_wc will always return success, even when the ioremap fails. Since the ATOMIC_IOMAP version returns NULL when the init fails, and callers check for a NULL return on error this is unexpected. During a device probe, where the ioremap failed, a crash can look like this: BUG: unable to handle page fault for address: 0000000000210000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page Oops: 0002 [#1] PREEMPT SMP CPU: 0 PID: 177 Comm: RIP: 0010:fill_page_dma [i915] gen8_ppgtt_create [i915] i915_ppgtt_create [i915] intel_gt_init [i915] i915_gem_init [i915] i915_driver_probe [i915] pci_device_probe really_probe driver_probe_device The remap failure occurred much earlier in the probe. If it had been propagated, the driver would have exited with an error. Return NULL on ioremap failure. [akpm@linux-foundation.org: detect ioremap_wc() errors earlier] Fixes: cafaf14a ("io-mapping: Always create a struct to hold metadata about the io-mapping") Signed-off-by:Michael J. Ruhl <michael.j.ruhl@intel.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Reviewed-by:
Andrew Morton <akpm@linux-foundation.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20200721171936.81563-1-michael.j.ruhl@intel.com Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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