From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F788C43334 for ; Thu, 16 Jun 2022 08:42:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AEBE26B0072; Thu, 16 Jun 2022 04:42:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A9B296B0073; Thu, 16 Jun 2022 04:42:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 989E86B0074; Thu, 16 Jun 2022 04:42:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 8AB056B0072 for ; Thu, 16 Jun 2022 04:42:15 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 5AA4220655 for ; Thu, 16 Jun 2022 08:42:15 +0000 (UTC) X-FDA: 79583457030.15.27F2EAD Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf08.hostedemail.com (Postfix) with ESMTP id D4E3416008C for ; Thu, 16 Jun 2022 08:42:14 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2D7BB12FC; Thu, 16 Jun 2022 01:42:14 -0700 (PDT) Received: from [10.57.69.164] (unknown [10.57.69.164]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 09D883F7F5; Thu, 16 Jun 2022 01:42:11 -0700 (PDT) Message-ID: <75aa779d-785f-6515-51cd-654e8c5d18f5@arm.com> Date: Thu, 16 Jun 2022 09:42:10 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v2 2/4] mm: kasan: Skip unpoisoning of user pages Content-Language: en-US To: Catalin Marinas , Andrey Ryabinin , Andrey Konovalov Cc: Will Deacon , Peter Collingbourne , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org References: <20220610152141.2148929-1-catalin.marinas@arm.com> <20220610152141.2148929-3-catalin.marinas@arm.com> From: Vincenzo Frascino In-Reply-To: <20220610152141.2148929-3-catalin.marinas@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655368935; a=rsa-sha256; cv=none; b=yWHagLg2ie8FG4rwPJSUZiNGzOU92ulwtGxT7l6trUsjr3LsK+0ewbaUBr9w/lPeGWvj4O pUIqznsgAHO9TWRpJOR54xiEPl8V80DDj4UrRwysIelGT83kpbHkqx8nE/gfY+/qI+tNEm fxxfoSL0a7P8DjoR68H4cHptjvzjjiE= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=none; spf=pass (imf08.hostedemail.com: domain of vincenzo.frascino@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=vincenzo.frascino@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655368935; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qiDoDM0a04NQq98uvEW0S1Dv2gGG9It0Aj6P0RZCzz4=; b=BD6XCAdiqiysDcP10T9vYtVITjBwG1zyjS6tMjeyY5S0J+LNDUZbwohLErMrvbknAzDZ2f G8cl6lVZEkAKU+vyfq1suC4cqzMkzpjsK07qO1Q1BGQqtEShzE7fXagXKHrbx3eBUw/ays dbM0ZuIWPJ6Y5Pf4efZZ2KwTqxf44vA= X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D4E3416008C X-Stat-Signature: mkkqexezfffowsrqx8abzmp7oxc6n64h Authentication-Results: imf08.hostedemail.com; dkim=none; spf=pass (imf08.hostedemail.com: domain of vincenzo.frascino@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=vincenzo.frascino@arm.com; dmarc=pass (policy=none) header.from=arm.com X-HE-Tag: 1655368934-331429 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 6/10/22 16:21, Catalin Marinas wrote: > Commit c275c5c6d50a ("kasan: disable freed user page poisoning with HW > tags") added __GFP_SKIP_KASAN_POISON to GFP_HIGHUSER_MOVABLE. A similar > argument can be made about unpoisoning, so also add > __GFP_SKIP_KASAN_UNPOISON to user pages. To ensure the user page is > still accessible via page_address() without a kasan fault, reset the > page->flags tag. > > With the above changes, there is no need for the arm64 > tag_clear_highpage() to reset the page->flags tag. > > Signed-off-by: Catalin Marinas > Cc: Andrey Ryabinin > Cc: Andrey Konovalov > Cc: Peter Collingbourne > Cc: Vincenzo Frascino > --- > arch/arm64/mm/fault.c | 1 - > include/linux/gfp.h | 2 +- > mm/page_alloc.c | 7 +++++-- > 3 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index c5e11768e5c1..cdf3ffa0c223 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -927,6 +927,5 @@ struct page *alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma, > void tag_clear_highpage(struct page *page) > { > mte_zero_clear_page_tags(page_address(page)); > - page_kasan_tag_reset(page); > set_bit(PG_mte_tagged, &page->flags); > } > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 2d2ccae933c2..0ace7759acd2 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -348,7 +348,7 @@ struct vm_area_struct; > #define GFP_DMA32 __GFP_DMA32 > #define GFP_HIGHUSER (GFP_USER | __GFP_HIGHMEM) > #define GFP_HIGHUSER_MOVABLE (GFP_HIGHUSER | __GFP_MOVABLE | \ > - __GFP_SKIP_KASAN_POISON) > + __GFP_SKIP_KASAN_POISON | __GFP_SKIP_KASAN_UNPOISON) > #define GFP_TRANSHUGE_LIGHT ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ > __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM) > #define GFP_TRANSHUGE (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM) > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index e008a3df0485..f6ed240870bc 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2397,6 +2397,7 @@ inline void post_alloc_hook(struct page *page, unsigned int order, > bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) && > !should_skip_init(gfp_flags); > bool init_tags = init && (gfp_flags & __GFP_ZEROTAGS); > + int i; > Nit: Since "i" is not used outside of the for loop context we could use the contract form "for (int i = 0; ..." which is allowed by C11. > set_page_private(page, 0); > set_page_refcounted(page); > @@ -2422,8 +2423,6 @@ inline void post_alloc_hook(struct page *page, unsigned int order, > * should be initialized as well). > */ > if (init_tags) { > - int i; > - > /* Initialize both memory and tags. */ > for (i = 0; i != 1 << order; ++i) > tag_clear_highpage(page + i); > @@ -2438,6 +2437,10 @@ inline void post_alloc_hook(struct page *page, unsigned int order, > /* Note that memory is already initialized by KASAN. */ > if (kasan_has_integrated_init()) > init = false; > + } else { > + /* Ensure page_address() dereferencing does not fault. */ > + for (i = 0; i != 1 << order; ++i) > + page_kasan_tag_reset(page + i); > } > /* If memory is still not initialized, do it now. */ > if (init) Either way: Reviewed-by: Vincenzo Frascino -- Regards, Vincenzo