The patch titled
Subject: io-mapping: indicate mapping failure
has been added to the -mm tree. Its filename is
io-mapping-indicate-mapping-failure.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/io-mapping-indicate-mapping-failure.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/io-mapping-indicate-mapping-failure.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: "Michael J. Ruhl" <michael.j.ruhl@xxxxxxxxx>
Subject: 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.
Link: http://lkml.kernel.org/r/20200721171936.81563-1-michael.j.ruhl@xxxxxxxxx
Fixes: cafaf14a5d8f ("io-mapping: Always create a struct to hold metadata about the io-mapping")
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/io-mapping.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/io-mapping.h~io-mapping-indicate-mapping-failure
+++ a/include/linux/io-mapping.h
@@ -118,7 +118,7 @@ io_mapping_init_wc(struct io_mapping *io
iomap->prot = pgprot_noncached(PAGE_KERNEL);
#endif
- return iomap;
+ return iomap->iomem ? iomap : NULL;
}
static inline void
_
Patches currently in -mm which might be from michael.j.ruhl@xxxxxxxxx are
io-mapping-indicate-mapping-failure.patch
