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Mon, 29 Mar 2021 09:23:25 +0000 (UTC) Received: from [10.36.114.205] (ovpn-114-205.ams2.redhat.com [10.36.114.205]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2738F5D9F0; Mon, 29 Mar 2021 09:23:23 +0000 (UTC) To: Sergei Trofimovich , Vlastimil Babka , Andrew Morton , Andrey Konovalov Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20210327180348.137d8fe2@sf> <20210327182144.3213887-1-slyfox@gentoo.org> From: David Hildenbrand Organization: Red Hat GmbH Subject: Re: [PATCH v2] mm: page_alloc: ignore init_on_free=1 for debug_pagealloc=1 Message-ID: Date: Mon, 29 Mar 2021 11:23:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210327182144.3213887-1-slyfox@gentoo.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 1DD3E2000252 X-Stat-Signature: ajmfukubsefxbunn5qf7smht1du3mgw1 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf18; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617009827-13910 Content-Transfer-Encoding: quoted-printable 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: On 27.03.21 19:21, Sergei Trofimovich wrote: > On !ARCH_SUPPORTS_DEBUG_PAGEALLOC (like ia64) debug_pagealloc=3D1 > implies page_poison=3Don: >=20 > if (page_poisoning_enabled() || > (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && > debug_pagealloc_enabled())) > static_branch_enable(&_page_poisoning_enabled); >=20 > page_poison=3Don needs to init_on_free=3D1. >=20 > Before the change id happened too late for the following case: > - have PAGE_POISONING=3Dy > - have page_poison unset > - have !ARCH_SUPPORTS_DEBUG_PAGEALLOC arch (like ia64) > - have init_on_free=3D1 > - have debug_pagealloc=3D1 >=20 > That way we get both keys enabled: > - static_branch_enable(&init_on_free); > - static_branch_enable(&_page_poisoning_enabled); >=20 > which leads to poisoned pages returned for __GFP_ZERO pages. >=20 > After the change we execute only: > - static_branch_enable(&_page_poisoning_enabled); > and ignore init_on_free=3D1. >=20 > CC: Vlastimil Babka > CC: Andrew Morton > CC: linux-mm@kvack.org > CC: David Hildenbrand > CC: Andrey Konovalov > Link: https://lkml.org/lkml/2021/3/26/443 Again, Fixes: tag? IOW, which commit initially broke it. > Signed-off-by: Sergei Trofimovich > --- > mm/page_alloc.c | 30 +++++++++++++++++------------- > 1 file changed, 17 insertions(+), 13 deletions(-) >=20 > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d57d9b4f7089..10a8a1d28c11 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -764,32 +764,36 @@ static inline void clear_page_guard(struct zone *= zone, struct page *page, > */ > void init_mem_debugging_and_hardening(void) > { > + bool page_poison_requested =3D page_poisoning_enabled(); s/page_poison_requested/page_poisoning_requested/ And I wonder if you should just initialize to "false" here. Without CONFIG_PAGE_POISONING, page_poisoning_enabled() will always=20 return false, so it seems unnecessary. > + > +#ifdef CONFIG_PAGE_POISONING > + /* > + * Page poisoning is debug page alloc for some arches. If > + * either of those options are enabled, enable poisoning. > + */ > + if (page_poisoning_enabled() || > + (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && > + debug_pagealloc_enabled())) { > + static_branch_enable(&_page_poisoning_enabled); > + page_poison_requested =3D true; > + } > +#endif Apart from that, looks good. --=20 Thanks, David / dhildenb