+ selftests-set-overcommit_policy-as-overcommit_always.patch added to mm-unstable branch

+ selftests-set-overcommit_policy-as-overcommit_always.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: selftests: set overcommit_policy as OVERCOMMIT_ALWAYS
has been added to the -mm mm-unstable branch.  Its filename is
     selftests-set-overcommit_policy-as-overcommit_always.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-set-overcommit_policy-as-overcommit_always.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
Subject: selftests: set overcommit_policy as OVERCOMMIT_ALWAYS
Date: Tue, 14 Mar 2023 09:53:51 +0530

The kernel's default behaviour is to obstruct the allocation of high
virtual address as it handles memory overcommit in a heuristic manner. 
Setting the parameter as OVERCOMMIT_ALWAYS, ensures kernel isn't
susceptible to the availability of a platform's physical memory when
denying a memory allocation request.

Link: https://lkml.kernel.org/r/20230314042351.13134-4-chaitanyas.prakash@arm.com
Signed-off-by: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/tools/testing/selftests/mm/run_vmtests.sh~selftests-set-overcommit_policy-as-overcommit_always
+++ a/tools/testing/selftests/mm/run_vmtests.sh
@@ -220,7 +220,15 @@ CATEGORY="mremap" run_test ./mremap_test
 CATEGORY="hugetlb" run_test ./thuge-gen
 
 if [ $VADDR64 -ne 0 ]; then
+
+	# set overcommit_policy as OVERCOMMIT_ALWAYS so that kernel
+	# allows high virtual address allocation requests independent
+	# of platform's physical memory.
+
+	prev_policy=$(cat /proc/sys/vm/overcommit_memory)
+	echo 1 > /proc/sys/vm/overcommit_memory
 	CATEGORY="hugevm" run_test ./virtual_address_range
+	echo $prev_policy > /proc/sys/vm/overcommit_memory
 
 	# virtual address 128TB switch test
 	CATEGORY="hugevm" run_test ./va_128TBswitch.sh
_

Patches currently in -mm which might be from chaitanyas.prakash@arm.com are

selftests-change-map_chunk_size.patch
selftests-change-nr_chunks_high-for-aarch64.patch
selftests-set-overcommit_policy-as-overcommit_always.patch