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([58.123.110.97]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d315f30027sm10547465ad.25.2026.08.11.09.20.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Aug 2026 09:20:31 -0700 (PDT) From: Hyunwoo Kim To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, imv4bel@gmail.com Subject: [PATCH v2 0/2] mm/pagewalk: fix stale walk->action escaping walk_pmd_range() Date: Wed, 12 Aug 2026 01:18:56 +0900 Message-ID: <20260811161949.3879321-1-imv4bel@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit walk_pmd_range() could return with walk->action left at ACTION_AGAIN, which causes walk_pud_range() to retry the PUD walk and invoke the walk callbacks twice over the same range. Patch 1 is the fix. Patch 2 adds a regression test for it. Changes in v2: - 1/2: reworked the changelog along the lines Lorenzo suggested and said how the bug was found; the fix itself is unchanged (Lorenzo) - 2/2: new, races smaps against MADV_DONTNEED and checks that Rss does not come out twice as large as what was faulted in (Lorenzo) - v1: https://lore.kernel.org/r/anmdrYGVqM-U4vlo@v4bel Hyunwoo Kim (2): mm/pagewalk: fix stale walk->action escaping walk_pmd_range() selftests/mm: add stale walk->action race test mm/pagewalk.c | 6 +- tools/testing/selftests/mm/.gitignore | 1 + tools/testing/selftests/mm/Makefile | 2 + tools/testing/selftests/mm/ksft_pagewalk.sh | 4 + .../testing/selftests/mm/pagewalk_race_test.c | 138 ++++++++++++++++++ tools/testing/selftests/mm/run_vmtests.sh | 2 + tools/testing/selftests/mm/vm_util.h | 1 + 7 files changed, 150 insertions(+), 4 deletions(-) create mode 100755 tools/testing/selftests/mm/ksft_pagewalk.sh create mode 100644 tools/testing/selftests/mm/pagewalk_race_test.c -- 2.43.0