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Mon, 08 Dec 2025 22:28:00 -0500 X-MC-Unique: P4iN0WunM0CoN3RLOuYODw-1 X-Mimecast-MFC-AGG-ID: P4iN0WunM0CoN3RLOuYODw_1765250878 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A24091956088; Tue, 9 Dec 2025 03:27:57 +0000 (UTC) Received: from localhost (unknown [10.72.112.51]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2678719560AD; Tue, 9 Dec 2025 03:27:54 +0000 (UTC) Date: Tue, 9 Dec 2025 11:27:50 +0800 From: Baoquan He To: Andrey Konovalov Cc: linux-mm@kvack.org, ryabinin.a.a@gmail.com, glider@google.com, dvyukov@google.com, vincenzo.frascino@arm.com, akpm@linux-foundation.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, elver@google.com, sj@kernel.org, lorenzo.stoakes@oracle.com, snovitoll@gmail.com, christophe.leroy@csgroup.eu Subject: Re: [PATCH v4 02/12] mm/kasan: move kasan= code to common place Message-ID: References: <20251128033320.1349620-1-bhe@redhat.com> <20251128033320.1349620-3-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Rspamd-Queue-Id: 0945114000B X-Stat-Signature: biuirpm8xpj3ot9riznsuun764xmm4cn X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1765250884-246563 X-HE-Meta: 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 4QbLvMlD qVgPpUDUEDEDqX0+bXsyNyEJHmgT9hTINoDCEylL1K+QS9yeGUi5/vNvw/kGT740PXL1rSsqeDApjecPa9+M5B/u9AXic9PNyE3WAjIJNXSCWpVe93GcskBsEtUGxXuqsb2If7vxD3TZJHXjel4rMFeevmyOSnd0KVGaKT6pbJl2dO1wVmyF0n2x7Dw== 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: List-Subscribe: List-Unsubscribe: On 12/04/25 at 05:39pm, Andrey Konovalov wrote: > On Fri, Nov 28, 2025 at 4:33 AM Baoquan He wrote: > > > > This allows generic and sw_tags to be set in kernel cmdline too. > > > > When at it, rename 'kasan_arg' to 'kasan_arg_disabled' as a bool > > variable. And expose 'kasan_flag_enabled' to kasan common place > > too. > > This asks to be two separate patches. Makes sense to me, thanks.. > > > > > This is prepared for later adding kernel parameter kasan=on|off for > > all three kasan modes. > > > > Signed-off-by: Baoquan He > > --- > > include/linux/kasan-enabled.h | 4 +++- > > mm/kasan/common.c | 20 ++++++++++++++++++-- > > mm/kasan/hw_tags.c | 28 ++-------------------------- > > 3 files changed, 23 insertions(+), 29 deletions(-) > > > > diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h > > index 9eca967d8526..b05ec6329fbe 100644 > > --- a/include/linux/kasan-enabled.h > > +++ b/include/linux/kasan-enabled.h > > @@ -4,13 +4,15 @@ > > > > #include > > > > -#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS) > > These changes of moving/removing CONFIG_ARCH_DEFER_KASAN also seem to > belong to a separate patch (or should be combined with patch 12?); the > commit message does not even mention them. Yes, combining tit with patch 12 sounds great. I will move patch 12 to earlier oder. > > > +extern bool kasan_arg_disabled; > > + > > /* > > * Global runtime flag for KASAN modes that need runtime control. > > * Used by ARCH_DEFER_KASAN architectures and HW_TAGS mode. > > */ > > DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled); > > So kasan_flag_enabled is now always exposed here... > > > > > +#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS) > > but the functions that use it are not. Why? Good question. I didn't consider this reasonably. At the beginning, I thought it could cause problem if people has specified 'kasan=off' before patch 12 when bisecting. That's why put kasan_arg_disabled and kasan_flag_enabled declaration outside of any ifdeffery scope. Now after reconsiderring, putting patch 12 earlier can solve the problem. Thanks for careful reivewing, all suggestions are good and taken. > > > > /* > > * Runtime control for shadow memory initialization or HW_TAGS mode. > > * Uses static key for architectures that need deferred KASAN or HW_TAGS. > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > > index 1d27f1bd260b..ac14956986ee 100644 > > --- a/mm/kasan/common.c > > +++ b/mm/kasan/common.c > > @@ -32,14 +32,30 @@ > > #include "kasan.h" > > #include "../slab.h" > > > > -#if defined(CONFIG_ARCH_DEFER_KASAN) || defined(CONFIG_KASAN_HW_TAGS) > > /* > > * Definition of the unified static key declared in kasan-enabled.h. > > * This provides consistent runtime enable/disable across KASAN modes. > > */ > > DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled); > > EXPORT_SYMBOL_GPL(kasan_flag_enabled); > > -#endif > > + > > +bool kasan_arg_disabled __ro_after_init; > > +/* kasan=off/on */ > > +static int __init early_kasan_flag(char *arg) > > +{ > > + if (!arg) > > + return -EINVAL; > > + > > + if (!strcmp(arg, "off")) > > + kasan_arg_disabled = true; > > + else if (!strcmp(arg, "on")) > > + kasan_arg_disabled = false; > > + else > > + return -EINVAL; > > + > > + return 0; > > +} > > +early_param("kasan", early_kasan_flag); > > > > struct slab *kasan_addr_to_slab(const void *addr) > > { > > diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c > > index 1c373cc4b3fa..709c91abc1b1 100644 > > --- a/mm/kasan/hw_tags.c > > +++ b/mm/kasan/hw_tags.c > > @@ -22,12 +22,6 @@ > > > > #include "kasan.h" > > > > -enum kasan_arg { > > - KASAN_ARG_DEFAULT, > > - KASAN_ARG_OFF, > > - KASAN_ARG_ON, > > -}; > > - > > enum kasan_arg_mode { > > KASAN_ARG_MODE_DEFAULT, > > KASAN_ARG_MODE_SYNC, > > @@ -41,7 +35,6 @@ enum kasan_arg_vmalloc { > > KASAN_ARG_VMALLOC_ON, > > }; > > > > -static enum kasan_arg kasan_arg __ro_after_init; > > static enum kasan_arg_mode kasan_arg_mode __ro_after_init; > > static enum kasan_arg_vmalloc kasan_arg_vmalloc __initdata; > > > > @@ -81,23 +74,6 @@ unsigned int kasan_page_alloc_sample_order = PAGE_ALLOC_SAMPLE_ORDER_DEFAULT; > > > > DEFINE_PER_CPU(long, kasan_page_alloc_skip); > > > > -/* kasan=off/on */ > > -static int __init early_kasan_flag(char *arg) > > -{ > > - if (!arg) > > - return -EINVAL; > > - > > - if (!strcmp(arg, "off")) > > - kasan_arg = KASAN_ARG_OFF; > > - else if (!strcmp(arg, "on")) > > - kasan_arg = KASAN_ARG_ON; > > - else > > - return -EINVAL; > > - > > - return 0; > > -} > > -early_param("kasan", early_kasan_flag); > > - > > /* kasan.mode=sync/async/asymm */ > > static int __init early_kasan_mode(char *arg) > > { > > @@ -222,7 +198,7 @@ void kasan_init_hw_tags_cpu(void) > > * When this function is called, kasan_flag_enabled is not yet > > * set by kasan_init_hw_tags(). Thus, check kasan_arg instead. > > */ > > - if (kasan_arg == KASAN_ARG_OFF) > > + if (kasan_arg_disabled) > > return; > > > > /* > > @@ -240,7 +216,7 @@ void __init kasan_init_hw_tags(void) > > return; > > > > /* If KASAN is disabled via command line, don't initialize it. */ > > - if (kasan_arg == KASAN_ARG_OFF) > > + if (kasan_arg_disabled) > > return; > > > > switch (kasan_arg_mode) { > > -- > > 2.41.0 > > >