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[96.67.55.147]) by mx.google.com with ESMTPS id v41si1656018qta.348.2019.06.18.18.23.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Jun 2019 18:23:00 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of riel@shelob.surriel.com designates 96.67.55.147 as permitted sender) client-ip=96.67.55.147; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of riel@shelob.surriel.com designates 96.67.55.147 as permitted sender) smtp.mailfrom=riel@shelob.surriel.com Received: from imladris.surriel.com ([96.67.55.152]) by shelob.surriel.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92) (envelope-from ) id 1hdPJR-00064w-2v; Tue, 18 Jun 2019 21:22:57 -0400 Message-ID: Subject: Re: [PATCH 1/1] fork,memcg: alloc_thread_stack_node needs to set tsk->stack From: Rik van Riel To: Andrea Arcangeli , Andrew Morton Cc: linux-mm@kvack.org, Roman Gushchin , Michal Hocko Date: Tue, 18 Jun 2019 21:22:56 -0400 In-Reply-To: <20190619011450.28048-1-aarcange@redhat.com> References: <20190619011450.28048-1-aarcange@redhat.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-j8zifAkn0SkfxwqrgUnv" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --=-j8zifAkn0SkfxwqrgUnv Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2019-06-18 at 21:14 -0400, Andrea Arcangeli wrote: > Commit 5eed6f1dff87bfb5e545935def3843edf42800f2 corrected two > instances, but there was a third instance of this bug. >=20 > Without setting tsk->stack, if memcg_charge_kernel_stack fails, it'll > execute free_thread_stack() on a dangling pointer. >=20 > Enterprise kernels are compiled with VMAP_STACK=3Dy so this isn't > critical, but custom VMAP_STACK=3Dn builds should have some performance > advantage, with the drawback of risking to fail fork because > compaction didn't succeed. So as long as VMAP_STACK=3Dn is a supported > option it's worth fixing it upstream. >=20 > Fixes: 9b6f7e163cd0 ("mm: rework memcg kernel stack accounting") > Signed-off-by: Andrea Arcangeli Reviewed-by: Rik van Riel --=20 All Rights Reversed. --=-j8zifAkn0SkfxwqrgUnv Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEKR73pCCtJ5Xj3yADznnekoTE3oMFAl0JjnAACgkQznnekoTE 3oMOswf/djcJCMVBnU5Cmi4fAHNdioTMMgIwY0amYoEsKD9UK8CFtcWdcV4pZT0X SlRYwbQeiyXRrwvT8bF9Pn/7veo3faq6L+UZVsGtavHY3dyUJSxfZN1RNn7KDUEA YINnOjR0OpDznMwStaYWa+vaFHl8+spY01mn8hquLkd24TTzqjnc/xxr6NupYgSy BJcQnoI+zcRSwRyyiBDHk1sC5iVwxqygLBr79lHyyFzS7vXXlJCUp/8ts6nYNesX KdQ8JX8IMk8iJ640XcW5g1eZc4TP1jeDkSruB+2gXzgcjJrGLynxF8kO/j0Ji1fR jZFvNRr+sZHJkFVIRYAiXmj4JP15IQ== =7AjD -----END PGP SIGNATURE----- --=-j8zifAkn0SkfxwqrgUnv--