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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 D603AC2D0E5 for ; Wed, 25 Mar 2020 17:40:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9CC9320789 for ; Wed, 25 Mar 2020 17:40:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="g8b4hEc6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9CC9320789 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 2F5146B00BC; Wed, 25 Mar 2020 13:40:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2A5EF6B00BD; Wed, 25 Mar 2020 13:40:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1BB5F6B00BE; Wed, 25 Mar 2020 13:40:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0253.hostedemail.com [216.40.44.253]) by kanga.kvack.org (Postfix) with ESMTP id 04AAB6B00BC for ; Wed, 25 Mar 2020 13:40:42 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id D03638248047 for ; Wed, 25 Mar 2020 17:40:42 +0000 (UTC) X-FDA: 76634599524.28.stem11_629444540913 X-HE-Tag: stem11_629444540913 X-Filterd-Recvd-Size: 5751 Received: from mail-wm1-f65.google.com (mail-wm1-f65.google.com [209.85.128.65]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Wed, 25 Mar 2020 17:40:42 +0000 (UTC) Received: by mail-wm1-f65.google.com with SMTP id z5so3431285wml.5 for ; Wed, 25 Mar 2020 10:40:42 -0700 (PDT) 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:content-transfer-encoding; bh=bWTI1JffKDq1SxzQbTO8bbvWDvUXAH7ujOPm/LqXyk8=; b=g8b4hEc6JhJ0BlfNAy10pKaSDHiBTAfY1v3yRhknWkdleoDA4hZAolYkYCbflCpiEi yfPTpVCM0OCoAP9aBkWyJw1eJmbk9YF/8OG46Y7VxT/B2DnuL7fCKeu97H90LgBbm00j o/djuUPI8JQlzZsrxPQ1abRC0ixHz8WDnWyKfXcYyvECSkAl+Xt0vEbJpQzhWw6k4FTx In2NOHUF1vZUi+4ffRmkX+Gi2FRWH2ITVe+QU5Jb9a0vHcFR2xjufs73bQI5x9DPYL8O 3DQ9qfSBif9OUPeq12RzxoEnUkwtpnE3TQy00knI7KlGDu2tQ1eo8rgaFSZMN9F/uBk/ 6tRg== 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:content-transfer-encoding; bh=bWTI1JffKDq1SxzQbTO8bbvWDvUXAH7ujOPm/LqXyk8=; b=k52kdeYpRg44ga4BWgnQYqUtMAS2Trld44qt0PO0wF/q2nxo+ZUivUzqfitwS+k+oN MtDITeatOI0rMaBUQQu8F/XcF2kOF4ZsnLR34bmq9y1PoCjYoTaIAa57818pZvHvDwWb PYqxO/GqqJh1JtTlB/E2qOTEloYubZHbBVbNeqVTQQOmFgLiM+3rendzAk6kWG8OIRvV DyIe14bmeypQzS0CLEuhlijWOWgMh+0uaniFx0uPwfVW+kvbpRKFJBjyj1SlimZgFEnW 7qZ2j4w9MFJUZzXyhf8Wfq6D9lqQX7bcgH97ALrYzBK7gr/E9yMXvHqp7eoSbFkkcIV+ Y3yw== X-Gm-Message-State: ANhLgQ0prdxatk/6YfkSeW2NoNcvk9nlbuMrUf2BiXQjRQN1I8LbADHX vNQpDb1m1L0HMbDKbFalN5LJGgTpWifSeAG29Isodw== X-Google-Smtp-Source: ADFU+vutzLXcPfK5BVNN9zhuXhpBt0+DVdbkjrq+aA8N6+uPnPJsPiyDmJsiin5i4C/x/29SDn/rU25RMByD+2X4/Ak= X-Received: by 2002:a1c:9846:: with SMTP id a67mr4345733wme.37.1585158040680; Wed, 25 Mar 2020 10:40:40 -0700 (PDT) MIME-Version: 1.0 References: <20200325161249.55095-1-glider@google.com> <20200325161249.55095-4-glider@google.com> <20200325161952.GF19542@dhcp22.suse.cz> In-Reply-To: From: Alexander Potapenko Date: Wed, 25 Mar 2020 18:40:29 +0100 Message-ID: Subject: Re: [PATCH v5 03/38] kmsan: gfp: introduce __GFP_NO_KMSAN_SHADOW To: Michal Hocko Cc: Vegard Nossum , Andrew Morton , Dmitry Vyukov , Marco Elver , Andrey Konovalov , Linux Memory Management List , Al Viro , Andreas Dilger , Andrey Ryabinin , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Christoph Hellwig , Christoph Hellwig , "Darrick J. Wong" , David Miller , Dmitry Torokhov , Eric Biggers , Eric Dumazet , Eric Van Hensbergen , Greg Kroah-Hartman , Harry Wentland , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jason Wang , Jens Axboe , Marek Szyprowski , Mark Rutland , "Martin K . Petersen" , Martin Schwidefsky , Matthew Wilcox , "Michael S. Tsirkin" , Michal Simek , Petr Mladek , Qian Cai , Randy Dunlap , Robin Murphy , Sergey Senozhatsky , Steven Rostedt , Takashi Iwai , "Theodore Ts'o" , Thomas Gleixner , Vasily Gorbik , Wolfram Sang Content-Type: text/plain; charset="UTF-8" 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 Wed, Mar 25, 2020 at 6:26 PM Alexander Potapenko wro= te: > > On Wed, Mar 25, 2020 at 5:19 PM Michal Hocko wrote: > > > > On Wed 25-03-20 17:12:14, glider@google.com wrote: > > > This flag is to be used by KMSAN runtime to mark that newly created > > > memory pages don't need KMSAN metadata backing them. > > > > I really dislike an idea of the gfp flag. If you need some form of > > exclusion for kmsan allocations then follow the pattern of memalloc_no{= fs,io}_{save,restore} > > History tells us that single usecase gfp flags are too tempting to abus= e > > and using incorrectly. > > Great idea, will do! > Guess PF_ flags isn't a scarce resource? Actually, no, we are out of bits in current->flags already. I could introduce a separate flag into struct task, but that won't work in interrupt contexts - how do you solve that problem for FS/IO allocations? --=20 Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Stra=C3=9Fe, 33 80636 M=C3=BCnchen Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg