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Date: Mon, 27 Jul 2020 16:04:40 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, "Michael J. Ruhl" <michael.j.ruhl@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, Mike Rapoport <rppt@...ux.ibm.com>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Chris Wilson <chris@...is-wilson.co.uk>, Daniel Vetter <daniel@...ll.ch>, Linus Torvalds <torvalds@...ux-foundation.org> Subject: [PATCH 4.14 61/64] io-mapping: indicate mapping failure From: Michael J. Ruhl <michael.j.ruhl@...el.com> commit e0b3e0b1a04367fc15c07f44e78361545b55357c upstream. 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@...ux-foundation.org: detect ioremap_wc() errors earlier] Fixes: cafaf14a5d8f ("io-mapping: Always create a struct to hold metadata about the io-mapping") Signed-off-by: Michael J. Ruhl <michael.j.ruhl@...el.com> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> Reviewed-by: Andrew Morton <akpm@...ux-foundation.org> Cc: Mike Rapoport <rppt@...ux.ibm.com> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com> Cc: Chris Wilson <chris@...is-wilson.co.uk> Cc: Daniel Vetter <daniel@...ll.ch> Cc: <stable@...r.kernel.org> Link: http://lkml.kernel.org/r/20200721171936.81563-1-michael.j.ruhl@intel.com Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- include/linux/io-mapping.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/include/linux/io-mapping.h +++ b/include/linux/io-mapping.h @@ -120,9 +120,12 @@ io_mapping_init_wc(struct io_mapping *io resource_size_t base, unsigned long size) { + iomap->iomem = ioremap_wc(base, size); + if (!iomap->iomem) + return NULL; + iomap->base = base; iomap->size = size; - iomap->iomem = ioremap_wc(base, size); #if defined(pgprot_noncached_wc) /* archs can't agree on a name ... */ iomap->prot = pgprot_noncached_wc(PAGE_KERNEL); #elif defined(pgprot_writecombine)
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