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Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Aishwarya TCV , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] selftests/mm: Specify requirement for PROC_MEM_ALWAYS_FORCE=y Message-ID: <0fef4cd9-e897-4830-9d37-f52ae9a33aa1@sirena.org.uk> References: <20260416-selftests-mm-proc-mem-always-force-v1-1-3f5865153c67@kernel.org> <17ea54b2-d43f-49a9-9dd4-d2330a8daa92@kernel.org> <5357ef55-15c0-4c66-867d-898fa7f51414@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="edS2AhsUYP5/qUYR" Content-Disposition: inline In-Reply-To: X-Cookie: Uh-oh!! I'm having TOO MUCH FUN!! X-Rspamd-Queue-Id: 2CBAD4000D X-Rspamd-Server: rspam07 X-Stat-Signature: cy3ucec9it9gg5r44ps8q7ptd5sbizrg X-Rspam-User: X-HE-Tag: 1776431435-431053 X-HE-Meta: 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 dieOCzvL btxjwxRneHSrMq3cUCF1jiwuBTOGVelMCD5HR1YffG8BMNHdEYUUqQc0E1K4KkDgfpZBIpqzWJxCxRoP268jCeUjb/zXXs6ejtF7jdNd4uMgDNtikHFHF7SFxTjkPBhryJPpbowAqhgJy9uV2LW6zQ/A5d9A9HG08SkMhOstHiROKiwLV8W0MlWWBUjNtQ3gQwOwAPsprC5wKFT2NGYotIwPDngU7kwQnKjaTdeqwsS8mTZ0Ygw1gYKBchmH9OTp0WdBhx/nvYBUfFuXXylKjjpQZKiilUHzATHbi0PRBkfXBSieIDiluoTmYOeT9SgyQzqmEou2iPp7NCCTKHQIVbCnGG63KeaghQny3gU+aPM7FJr6a6AjZOjop1f1oyPSuSYo0kNPR5KmIWMhJJsgOSdXdjWkpiEce8z5k Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --edS2AhsUYP5/qUYR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Apr 17, 2026 at 03:41:39PM +0300, Mike Rapoport wrote: > Yeah, the issue though is that open() succeeds regardless of PROC_MEM_ > setting in Kconfig. With restricted /proc/pid/mem the failure happens in > write(), and there we don't know what actually went wrong. > We can try checking errno, but it's fragile and it's better to fail the > test if write() failed IMO. Oh, that's unfortunate - you'd have hoped that opening for write would fail if you can't write. In that case you're probably right that we can't do much better, possibly adding a log message about the potential missing config but not sure that's worth it. --edS2AhsUYP5/qUYR Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmniMUQACgkQJNaLcl1U h9B8QQf9GBdnFFlhg4G17leX5BmBV6GXASVwvG8Q+tTuwrKGl/PCE1vc7KQY8eCr 4kAO+GSsVwvxnqz56RE1O92/xU99iiUd6wFbIfpc+ATWTN4jxZk9NIt/FasNFc6b 8gd/NYDi1rfRGXGxNwmYJCNh4Cx4XM0xe6VZ5dwhyRIXqE6LG89aC9UWROse3Q7n TR5nffGMskQ+FhIpjmEHm1UWcKaAj2yIQ9b3HPQBSBMN3nL1jQoH1Q6mjvaOpHOf 1lw3/0h0AfTPMOhiqRRTORBxnelE8WqAt4JwqwA7p4LgCg0JoNCnGtEQmwDznANJ rgPYZ66U8O5kbvDJMzCWk2bdqPCZNg== =v96S -----END PGP SIGNATURE----- --edS2AhsUYP5/qUYR--