diff options
authorMichael J. Ruhl <>2020-07-24 07:15:46 +0300
committerLinus Torvalds <>2020-07-24 22:42:42 +0300
commite0b3e0b1a04367fc15c07f44e78361545b55357c (patch)
parentd178770d8d21489abf5bafefcbb6d5243b482e9a (diff)
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. [ 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 <> Signed-off-by: Andrew Morton <> Reviewed-by: Andrew Morton <> Cc: Mike Rapoport <> Cc: Andy Shevchenko <> Cc: Chris Wilson <> Cc: Daniel Vetter <> Cc: <> Link: Signed-off-by: Linus Torvalds <>
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/io-mapping.h b/include/linux/io-mapping.h
index 0beaa3eba155..c75e4d3d8833 100644
--- a/include/linux/io-mapping.h
+++ b/include/linux/io-mapping.h
@@ -107,9 +107,12 @@ io_mapping_init_wc(struct io_mapping *iomap,
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)