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 X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF22BC2D0E4 for ; Tue, 17 Nov 2020 13:25:41 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6016A20781 for ; Tue, 17 Nov 2020 13:25:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Ws9G6B7b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6016A20781 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 866436B0068; Tue, 17 Nov 2020 08:25:40 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7EF3B6B006C; Tue, 17 Nov 2020 08:25:40 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 669C86B006E; Tue, 17 Nov 2020 08:25:40 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0060.hostedemail.com [216.40.44.60]) by kanga.kvack.org (Postfix) with ESMTP id 36A0E6B0068 for ; Tue, 17 Nov 2020 08:25:40 -0500 (EST) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id BA048180AD81F for ; Tue, 17 Nov 2020 13:25:39 +0000 (UTC) X-FDA: 77493982398.03.slip82_28014de27331 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin03.hostedemail.com (Postfix) with ESMTP id 9738228A4E8 for ; Tue, 17 Nov 2020 13:25:39 +0000 (UTC) X-HE-Tag: slip82_28014de27331 X-Filterd-Recvd-Size: 7565 Received: from mail-qk1-f193.google.com (mail-qk1-f193.google.com [209.85.222.193]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Tue, 17 Nov 2020 13:25:39 +0000 (UTC) Received: by mail-qk1-f193.google.com with SMTP id d28so20229113qka.11 for ; Tue, 17 Nov 2020 05:25:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WIETnv3xre8DddqB3eoABg/F+YsdxEpmfCm9JSQKUFk=; b=Ws9G6B7b9T2ql8gNctR3OGyYWvuBi6KB9dYkvha/s4Fdy+VKgIhfUwaNglXhaP6T1e 6QlEGtPHpVS2HMAOYaPpmPDgZ/FKLEV2qVeOHRnL55hiJ45OYnjJp9cEq4LI1ujP1ywv MGtBEhMlob6/Aon+sdujY3CV5/Rw5Eh5tzfEBdx1i+UsA9/39T76sFL1Mq4/OPOdUqqB Z7k1KFGI8V/Zm9VsGDv6GszybCCSg1/KTFJHXqWY37xtH+4qKxRrSvYG6HE72PMu71BY 1GsK03br4KCOGeQPO3QHSfAxPeHtnCmC+y5DYWSEklCdfF475a0BAWQQ4cVFTPllxTN/ m6Wg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WIETnv3xre8DddqB3eoABg/F+YsdxEpmfCm9JSQKUFk=; b=C6A6aebGm3lLvnFB9RaodZ+VS1P3owskgmL7qPKQfstIzExs5TSOGsREKHDVBG9vHe y4rgQst3uFtGn2DviP3ANeTgyluEjzUQAIoUU7chmyKe2lkofrtcBOCAJoQ5xCm98pb0 QUEffuU1mPDYaIXM+nMhjCvMpB+vtkN780k6o8mwZSWgV3yAdMVA/Ew1M7b3SJ+Oazfn 2ddc2uUtWAB3tGa0MJUmZOJz7fkgZ3vYvAx8SUCpd1/GHlCSfAVhIVbmfsMEbxjN8HfH Z4a15pceBgeYJOa6AETS3gZoDKumaPPWKX8qFuH6wzS5/A8Qjjc2b6M9lVH+Kh4kmtBX djXQ== X-Gm-Message-State: AOAM533mrssSRrweTB6E24OklRFUV18XLub8NeYXocLBI0kIW2Eqm1v2 hCWltZ8sZr5sAIGv5uaLcREiZ8UjNVwDFxpGalSf9Q== X-Google-Smtp-Source: ABdhPJxyYRSCHeuJLL6jo54bMELiM3vOiXgrTULSLW30Z9NUQKn0110b8QbG6skCbWCzpB52giTilG3a1QL9Mb0/h7o= X-Received: by 2002:a37:9747:: with SMTP id z68mr18952443qkd.424.1605619538042; Tue, 17 Nov 2020 05:25:38 -0800 (PST) MIME-Version: 1.0 References: <6f0a1e72783ddac000ac08e7315b1d7c0ca4ec51.1605305978.git.andreyknvl@google.com> In-Reply-To: <6f0a1e72783ddac000ac08e7315b1d7c0ca4ec51.1605305978.git.andreyknvl@google.com> From: Dmitry Vyukov Date: Tue, 17 Nov 2020 14:25:26 +0100 Message-ID: Subject: Re: [PATCH mm v3 18/19] kasan, mm: allow cache merging with no metadata To: Andrey Konovalov Cc: Andrew Morton , Catalin Marinas , Will Deacon , Vincenzo Frascino , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev , Linux ARM , Linux-MM , LKML Content-Type: text/plain; charset="UTF-8" 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 Fri, Nov 13, 2020 at 11:20 PM Andrey Konovalov wrote: > > The reason cache merging is disabled with KASAN is because KASAN puts its > metadata right after the allocated object. When the merged caches have > slightly different sizes, the metadata ends up in different places, which > KASAN doesn't support. > > It might be possible to adjust the metadata allocation algorithm and make > it friendly to the cache merging code. Instead this change takes a simpler > approach and allows merging caches when no metadata is present. Which is > the case for hardware tag-based KASAN with kasan.mode=prod. > > Co-developed-by: Vincenzo Frascino > Signed-off-by: Vincenzo Frascino > Signed-off-by: Andrey Konovalov > Link: https://linux-review.googlesource.com/id/Ia114847dfb2244f297d2cb82d592bf6a07455dba Somehow gerrit contains an old version... so I was going to independently propose what Marco already proposed as simplification... until I looked at the patch in the email :) Reviewed-by: Dmitry Vyukov > --- > include/linux/kasan.h | 21 +++++++++++++++++++-- > mm/kasan/common.c | 11 +++++++++++ > mm/slab_common.c | 3 ++- > 3 files changed, 32 insertions(+), 3 deletions(-) > > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > index 16cf53eac29b..173a8e81d001 100644 > --- a/include/linux/kasan.h > +++ b/include/linux/kasan.h > @@ -81,17 +81,30 @@ struct kasan_cache { > }; > > #ifdef CONFIG_KASAN_HW_TAGS > + > DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled); > + > static __always_inline bool kasan_enabled(void) > { > return static_branch_likely(&kasan_flag_enabled); > } > -#else > + > +#else /* CONFIG_KASAN_HW_TAGS */ > + > static inline bool kasan_enabled(void) > { > return true; > } > -#endif > + > +#endif /* CONFIG_KASAN_HW_TAGS */ > + > +slab_flags_t __kasan_never_merge(void); > +static __always_inline slab_flags_t kasan_never_merge(void) > +{ > + if (kasan_enabled()) > + return __kasan_never_merge(); > + return 0; > +} > > void __kasan_unpoison_range(const void *addr, size_t size); > static __always_inline void kasan_unpoison_range(const void *addr, size_t size) > @@ -238,6 +251,10 @@ static inline bool kasan_enabled(void) > { > return false; > } > +static inline slab_flags_t kasan_never_merge(void) > +{ > + return 0; > +} > static inline void kasan_unpoison_range(const void *address, size_t size) {} > static inline void kasan_alloc_pages(struct page *page, unsigned int order) {} > static inline void kasan_free_pages(struct page *page, unsigned int order) {} > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index cf874243efab..a5a4dcb1254d 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -87,6 +87,17 @@ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark) > } > #endif /* CONFIG_KASAN_STACK */ > > +/* > + * Only allow cache merging when stack collection is disabled and no metadata > + * is present. > + */ > +slab_flags_t __kasan_never_merge(void) > +{ > + if (kasan_stack_collection_enabled()) > + return SLAB_KASAN; > + return 0; > +} > + > void __kasan_alloc_pages(struct page *page, unsigned int order) > { > u8 tag; > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 0b5ae1819a8b..075b23ce94ec 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -19,6 +19,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -54,7 +55,7 @@ static DECLARE_WORK(slab_caches_to_rcu_destroy_work, > */ > #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ > SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ > - SLAB_FAILSLAB | SLAB_KASAN) > + SLAB_FAILSLAB | kasan_never_merge()) > > #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ > SLAB_CACHE_DMA32 | SLAB_ACCOUNT) > -- > 2.29.2.299.gdc1121823c-goog >