From: David Hildenbrand <david@redhat.com>
To: "Thomas Weißschuh" <thomas.weissschuh@linutronix.de>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Shuah Khan" <shuah@kernel.org>, "Dev Jain" <dev.jain@arm.com>,
"Thomas Gleixner" <tglx@linutronix.de>
Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/4] selftests/mm: virtual_address_range: Unmap chunks after validation
Date: Tue, 14 Jan 2025 14:11:58 +0100 [thread overview]
Message-ID: <059fcb77-7eea-4e3d-9b70-d88975388d9b@redhat.com> (raw)
In-Reply-To: <20250113-virtual_address_range-tests-v3-2-f4a8e6b7feed@linutronix.de>
On 13.01.25 14:15, Thomas Weißschuh wrote:
> 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.
>
> Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()")
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---
Acked-by: David Hildenbrand <david@redhat.com>
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2025-01-14 13:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-13 13:15 [PATCH v3 0/4] selftests/mm: virtual_address_range: Reduce memory usage and avoid VM_IO access Thomas Weißschuh
2025-01-13 13:15 ` [PATCH v3 1/4] selftests/mm: virtual_address_range: mmap() without PROT_WRITE Thomas Weißschuh
2025-01-13 15:46 ` Dev Jain
2025-01-13 13:15 ` [PATCH v3 2/4] selftests/mm: virtual_address_range: Unmap chunks after validation Thomas Weißschuh
2025-01-14 13:11 ` David Hildenbrand [this message]
2025-01-13 13:15 ` [PATCH v3 3/4] selftests/mm: vm_util: Split up /proc/self/smaps parsing Thomas Weißschuh
2025-01-14 10:01 ` David Hildenbrand
2025-01-13 13:15 ` [PATCH v3 4/4] selftests/mm: virtual_address_range: Avoid reading from VM_IO mappings Thomas Weißschuh
2025-01-14 1:25 ` Andrew Morton
2025-01-14 10:15 ` David Hildenbrand
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