selftests/mm: virtual_address_range: avoid reading from VM_IO mappings

The virtual_address_range selftest reads from the start of each mapping
listed in /proc/self/maps. However not all mappings ar

selftests/mm: virtual_address_range: avoid reading from VM_IO mappings

The virtual_address_range selftest reads from the start of each mapping
listed in /proc/self/maps. However not all mappings are valid to be
arbitrarily accessed.

For example the vvar data used for virtual clocks on x86 [vvar_vclock] can
only be accessed if 1) the kernel configuration enables virtual clocks and
2) the hypervisor provided the data for it. Only the VDSO itself has the
necessary information to know this. Since commit e93d2521b27f ("x86/vdso:
Split virtual clock pages into dedicated mapping") the virtual clock data
was split out into its own mapping, leading to EFAULT from read() during
the validation.

Check for the VM_IO flag as a proxy. It is present for the VVAR mappings
and MMIO ranges can be dangerous to access arbitrarily.

Link: https://lkml.kernel.org/r/20250114-virtual_address_range-tests-v4-4-6fd7269934a5@linutronix.de
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Fixes: e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping")
Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()")
Signed-off-by: Thomas Weißschuh <[email protected]>
Suggested-by: David Hildenbrand <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]/
Acked-by: David Hildenbrand <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Dev Jain <[email protected]>
Cc: Shuah Khan (Samsung OSG) <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests/mm: virtual_address_range: unmap chunks after validation

For each accessed chunk a PTE is created. More than 1GiB of PTEs is used
in this way. Remove each PTE after validating a chunk to

selftests/mm: virtual_address_range: unmap chunks after validation

For each accessed chunk a PTE is created. More than 1GiB of PTEs is used
in this way. Remove each PTE after validating a chunk to reduce peak
memory usage.

It is important to only unmap memory that previously mmap()ed, as
unmapping other mappings like the stack, heap or executable mappings will
crash the process.

The mappings read from /proc/self/maps and the return values from mmap()
don't allow a simple correlation due to merging and no guaranteed order.
To correlate the pointers and mappings use prctl(PR_SET_VMA_ANON_NAME).
While it introduces a test dependency, other alternatives would introduce
runtime or development overhead.

Link: https://lkml.kernel.org/r/20250114-virtual_address_range-tests-v4-2-6fd7269934a5@linutronix.de
Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()")
Signed-off-by: Thomas Weißschuh <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Dev Jain <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: Shuah Khan (Samsung OSG) <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests/mm: virtual_address_range: mmap() without PROT_WRITE

Patch series "selftests/mm: virtual_address_range: Reduce memory", v4.

The selftest started failing since commit e93d2521b27f ("x86/vd

selftests/mm: virtual_address_range: mmap() without PROT_WRITE

Patch series "selftests/mm: virtual_address_range: Reduce memory", v4.

The selftest started failing since commit e93d2521b27f ("x86/vdso: Split
virtual clock pages into dedicated mapping") was merged. While debugging
I stumbled upon some memory usage optimizations.

With these test now runs on a VM with only 60MiB of memory.


This patch (of 4):

When mapping a larger chunk than physical memory is available with
PROT_WRITE and overcommit is disabled, the mapping will fail. This will
prevent the test from running on systems with less then ~1GiB of memory
and triggering an inscrutinable test failure. As the mappings are never
written to anyways, the flag can be removed.

Link: https://lkml.kernel.org/r/20250114-virtual_address_range-tests-v4-0-6fd7269934a5@linutronix.de
Link: https://lkml.kernel.org/r/20250114-virtual_address_range-tests-v4-1-6fd7269934a5@linutronix.de
Fixes: 4e5ce33ceb32 ("selftests/vm: add a test for virtual address range mapping")
Signed-off-by: Thomas Weißschuh <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Acked-by: Dev Jain <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Shuah Khan (Samsung OSG) <[email protected]>
Cc: kernel test robot <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftest/mm: fix typo in virtual_address_range

The function name should be *hint* address, so correct it.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off

selftest/mm: fix typo in virtual_address_range

The function name should be *hint* address, so correct it.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Chunyan Zhang <[email protected]>
Reviewed-by: Charlie Jenkins <[email protected]>
Acked-by: Palmer Dabbelt <[email protected]>
Cc: Alexandre Ghiti <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()

Currently, VA exhaustion is being checked by passing a hint to mmap() and
expecting it to fail.

While populating the lo

selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()

Currently, VA exhaustion is being checked by passing a hint to mmap() and
expecting it to fail.

While populating the lower VA space, mmap() fails because we have
exhausted the space.

Then, in validate_lower_address_hint(), because mmap() fails, we
confirm that we have indeed exhausted the space. There is a circular
logic involved here.

Assume that there is a bug in mmap(), also assume that it exists
independent of whether you pass a hint address or not; that for some
reason it is not able to find a 1GB chunk. My idea is to assert the
exhaustion against some other method.

This patch makes a stricter test by successful
write() calls from /proc/self/maps to a dump file, confirming that a free
chunk is indeed not available.

[[email protected]: replace SZ_1GB with MAP_CHUNK_SIZE, tidy-up]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Dev Jain <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests/mm: virtual_address_range: Switch to ksft_exit_fail_msg

mmap() must not succeed in validate_lower_address_hint(), for if it does,
it is a bug in mmap() itself. Reflect this behaviour with

selftests/mm: virtual_address_range: Switch to ksft_exit_fail_msg

mmap() must not succeed in validate_lower_address_hint(), for if it does,
it is a bug in mmap() itself. Reflect this behaviour with
ksft_exit_fail_msg(). While at it, do some formatting changes.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Dev Jain <[email protected]>
Reviewed-by: Muhammad Usama Anjum <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests/mm: virtual_address_range: conform to TAP format output

Conform the layout, informational and status messages to TAP. No
functional change is intended other than the layout of output mess

selftests/mm: virtual_address_range: conform to TAP format output

Conform the layout, informational and status messages to TAP. No
functional change is intended other than the layout of output messages.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muhammad Usama Anjum <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests/mm: change NR_CHUNKS_HIGH for aarch64

Although there is a provision for 52 bit VA on arm64 platform, it remains
unutilised and higher addresses are not allocated. In order to
accommodate

selftests/mm: change NR_CHUNKS_HIGH for aarch64

Although there is a provision for 52 bit VA on arm64 platform, it remains
unutilised and higher addresses are not allocated. In order to
accommodate 4PB [2^52] virtual address space where supported,
NR_CHUNKS_HIGH is changed accordingly.

Array holding addresses is changed from static allocation to dynamic
allocation to accommodate its voluminous nature which otherwise might
overflow the stack.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Chaitanya S Prakash <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests/mm: change MAP_CHUNK_SIZE

Patch series "selftests: Fix virtual address range for arm64", v2.

When the virtual address range selftest is run on arm64 and x86 platforms,
it is observed that

selftests/mm: change MAP_CHUNK_SIZE

Patch series "selftests: Fix virtual address range for arm64", v2.

When the virtual address range selftest is run on arm64 and x86 platforms,
it is observed that both the low and high VA range iterations are skipped
when the MAP_CHUNK_SIZE is set to 16GB. The MAP_CHUNK_SIZE is changed to
1GB to resolve this issue, following which support for arm64 platform is
added by changing the NR_CHUNKS_HIGH for aarch64 to accommodate up to 4PB
of virtual address space allocation requests. Dynamic memory allocation
of array holding addresses is introduced to prevent overflow of the stack.
Finally, the overcommit_policy is set as OVERCOMMIT_ALWAYS to prevent the
kernel from denying a memory allocation request based on a platform's
physical memory availability.


This patch (of 3):

mmap() fails to allocate 16GB virtual space chunk, skipping both low and
high VA range iterations. Hence, reduce MAP_CHUNK_SIZE to 1GB and update
relevant macros as required.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Chaitanya S Prakash <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests/vm: rename selftests/vm to selftests/mm

Rename selftets/vm to selftests/mm for being more consistent with the
code, documentation, and tools directories, and won't be confused with
virtual

selftests/vm: rename selftests/vm to selftests/mm

Rename selftets/vm to selftests/mm for being more consistent with the
code, documentation, and tools directories, and won't be confused with
virtual machines.

[[email protected]: convert missing vm->mm changes]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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