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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 696C1C433FE for ; Tue, 21 Dec 2021 09:17:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236228AbhLUJRT (ORCPT ); Tue, 21 Dec 2021 04:17:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235102AbhLUJRS (ORCPT ); Tue, 21 Dec 2021 04:17:18 -0500 Received: from mail-qt1-x82f.google.com (mail-qt1-x82f.google.com [IPv6:2607:f8b0:4864:20::82f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 695C8C061574 for ; Tue, 21 Dec 2021 01:17:18 -0800 (PST) Received: by mail-qt1-x82f.google.com with SMTP id q14so12257003qtx.10 for ; Tue, 21 Dec 2021 01:17:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=GsQvaI7A1wdAxmeueWYfyyxE+cFPs78qCZTLJz4uaZA=; b=Rc/RWdXiq31wiYWyOfSAe3/XzoJsf6eSWj3UqAgso2+3tudJ+pEqajnSp0MX5Ivnfb v7E10N+xuZFfHtjQM2mSDXPtJfFPDEwzTYQ3cAKbGxk7QHB6gC2o3EvLU9VxEEns/tiz X1hl9TOtbzs3rrNAPQfZzn1wMayO+xs4+rDfx89HM8IU5iDPOT9NL2pyYQKO4MieUVPv tZpDXlsBkQYTVoCKgb4E1a6VElwwvxzHfS+8kWzB4UhdcKmmdDvCJNZjZ+cu8BXn1cTz uwuxkPPIh0lj7g3SXk2jTJrWbMZh+Q99aVadlgxINr8y6JYEP+3uBwCpsJdKiymd9vwZ VDSQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=GsQvaI7A1wdAxmeueWYfyyxE+cFPs78qCZTLJz4uaZA=; b=QVqIF9Wm1wpUJIjHfoZ1/S2CLYiIJujkbR1p4BL0D2nQzxPA4Ja+xsCt+E8v4KrLwh 2QYR4X8QAQxAA9UDLGINOZvk65zubq/8LFbwzZR1Hajt1uPFiGJn6mE6Cn5NpyxwZaVF yJJ5lnlqfgh1dar7Nkd2f8NXRUaB2jg/idOy9s3YulrXEaHeEGL8h2PXX6knkoCMg6ap T/g3OyXQLW8+ogBkuCwMtDyA93xlVpANqv9hBgbHKRGo59KaxyhTvwFUJw1s56d0H4py 0vhgl8SSakS4Jbx77eD+2hhFARhRSQ2IAq2m0hlu38kHqZSiqo74M0+W/8C3l2Vw6lDc VkRg== X-Gm-Message-State: AOAM532qKmjSgMBNls6EzzfRhhrG0xmLAUPMmBAjtaXo6VD9y/EPICsG AiKlsNoKXU/58GW0r6Drw1nlqLVKViDZW0fE4wnXQA== X-Google-Smtp-Source: ABdhPJySaSkdGVLLYk9zgNVN+v/hvI55u4ES66+7QrRplSW+Lq21+NQDiGiG71v2c+6hNI+kO5z5N8ahWN2FEGKAbcM= X-Received: by 2002:ac8:5712:: with SMTP id 18mr1304135qtw.72.1640078237345; Tue, 21 Dec 2021 01:17:17 -0800 (PST) MIME-Version: 1.0 References: <92f3029f3647ab355450ed5c8252bad8cfae1e09.1640036051.git.andreyknvl@google.com> In-Reply-To: <92f3029f3647ab355450ed5c8252bad8cfae1e09.1640036051.git.andreyknvl@google.com> From: Alexander Potapenko Date: Tue, 21 Dec 2021 10:16:41 +0100 Message-ID: Subject: Re: [PATCH mm v4 07/39] mm: clarify __GFP_ZEROTAGS comment To: andrey.konovalov@linux.dev Cc: Marco Elver , Andrew Morton , Andrey Konovalov , Dmitry Vyukov , Andrey Ryabinin , kasan-dev , Linux Memory Management List , Vincenzo Frascino , Catalin Marinas , Will Deacon , Mark Rutland , Linux ARM , Peter Collingbourne , Evgenii Stepanov , LKML , Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 20, 2021 at 10:59 PM wrote: > > From: Andrey Konovalov Reviewed-by: Alexander Potapenko > > __GFP_ZEROTAGS is intended as an optimization: if memory is zeroed during > allocation, it's possible to set memory tags at the same time with little > performance impact. Perhaps you could mention this intention explicitly in the comment? Right now it still doesn't reference performance. > > Clarify this intention of __GFP_ZEROTAGS in the comment. > > Signed-off-by: Andrey Konovalov > --- > include/linux/gfp.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 0b2d2a636164..d6a184523ca2 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -228,8 +228,8 @@ struct vm_area_struct; > * > * %__GFP_ZERO returns a zeroed page on success. > * > - * %__GFP_ZEROTAGS returns a page with zeroed memory tags on success, if > - * __GFP_ZERO is set. > + * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory i= tself > + * is being zeroed (either via __GFP_ZERO or via init_on_alloc). > * > * %__GFP_SKIP_KASAN_POISON returns a page which does not need to be poi= soned > * on deallocation. Typically used for userspace pages. Currently only h= as an > -- > 2.25.1 > > -- > You received this message because you are subscribed to the Google Groups= "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an= email to kasan-dev+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgi= d/kasan-dev/92f3029f3647ab355450ed5c8252bad8cfae1e09.1640036051.git.andreyk= nvl%40google.com. --=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 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 041CCC433EF for ; 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charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gTW9uLCBEZWMgMjAsIDIwMjEgYXQgMTA6NTkgUE0gPGFuZHJleS5rb25vdmFsb3ZAbGludXgu ZGV2PiB3cm90ZToKPgo+IEZyb206IEFuZHJleSBLb25vdmFsb3YgPGFuZHJleWtudmxAZ29vZ2xl LmNvbT4KClJldmlld2VkLWJ5OiBBbGV4YW5kZXIgUG90YXBlbmtvIDxnbGlkZXJAZ29vZ2xlLmNv bT4KCj4KPiBfX0dGUF9aRVJPVEFHUyBpcyBpbnRlbmRlZCBhcyBhbiBvcHRpbWl6YXRpb246IGlm IG1lbW9yeSBpcyB6ZXJvZWQgZHVyaW5nCj4gYWxsb2NhdGlvbiwgaXQncyBwb3NzaWJsZSB0byBz ZXQgbWVtb3J5IHRhZ3MgYXQgdGhlIHNhbWUgdGltZSB3aXRoIGxpdHRsZQo+IHBlcmZvcm1hbmNl IGltcGFjdC4KUGVyaGFwcyB5b3UgY291bGQgbWVudGlvbiB0aGlzIGludGVudGlvbiBleHBsaWNp dGx5IGluIHRoZSBjb21tZW50PwpSaWdodCBub3cgaXQgc3RpbGwgZG9lc24ndCByZWZlcmVuY2Ug cGVyZm9ybWFuY2UuCgo+Cj4gQ2xhcmlmeSB0aGlzIGludGVudGlvbiBvZiBfX0dGUF9aRVJPVEFH UyBpbiB0aGUgY29tbWVudC4KPgo+IFNpZ25lZC1vZmYtYnk6IEFuZHJleSBLb25vdmFsb3YgPGFu ZHJleWtudmxAZ29vZ2xlLmNvbT4KPiAtLS0KPiAgaW5jbHVkZS9saW51eC9nZnAuaCB8IDQgKyst LQo+ICAxIGZpbGUgY2hhbmdlZCwgMiBpbnNlcnRpb25zKCspLCAyIGRlbGV0aW9ucygtKQo+Cj4g ZGlmZiAtLWdpdCBhL2luY2x1ZGUvbGludXgvZ2ZwLmggYi9pbmNsdWRlL2xpbnV4L2dmcC5oCj4g aW5kZXggMGIyZDJhNjM2MTY0Li5kNmExODQ1MjNjYTIgMTAwNjQ0Cj4gLS0tIGEvaW5jbHVkZS9s aW51eC9nZnAuaAo+ICsrKyBiL2luY2x1ZGUvbGludXgvZ2ZwLmgKPiBAQCAtMjI4LDggKzIyOCw4 IEBAIHN0cnVjdCB2bV9hcmVhX3N0cnVjdDsKPiAgICoKPiAgICogJV9fR0ZQX1pFUk8gcmV0dXJu cyBhIHplcm9lZCBwYWdlIG9uIHN1Y2Nlc3MuCj4gICAqCj4gLSAqICVfX0dGUF9aRVJPVEFHUyBy ZXR1cm5zIGEgcGFnZSB3aXRoIHplcm9lZCBtZW1vcnkgdGFncyBvbiBzdWNjZXNzLCBpZgo+IC0g KiBfX0dGUF9aRVJPIGlzIHNldC4KPiArICogJV9fR0ZQX1pFUk9UQUdTIHplcm9lcyBtZW1vcnkg dGFncyBhdCBhbGxvY2F0aW9uIHRpbWUgaWYgdGhlIG1lbW9yeSBpdHNlbGYKPiArICogaXMgYmVp bmcgemVyb2VkIChlaXRoZXIgdmlhIF9fR0ZQX1pFUk8gb3IgdmlhIGluaXRfb25fYWxsb2MpLgo+ ICAgKgo+ICAgKiAlX19HRlBfU0tJUF9LQVNBTl9QT0lTT04gcmV0dXJucyBhIHBhZ2Ugd2hpY2gg ZG9lcyBub3QgbmVlZCB0byBiZSBwb2lzb25lZAo+ICAgKiBvbiBkZWFsbG9jYXRpb24uIFR5cGlj YWxseSB1c2VkIGZvciB1c2Vyc3BhY2UgcGFnZXMuIEN1cnJlbnRseSBvbmx5IGhhcyBhbgo+IC0t Cj4gMi4yNS4xCj4KPiAtLQo+IFlvdSByZWNlaXZlZCB0aGlzIG1lc3NhZ2UgYmVjYXVzZSB5b3Ug YXJlIHN1YnNjcmliZWQgdG8gdGhlIEdvb2dsZSBHcm91cHMgImthc2FuLWRldiIgZ3JvdXAuCj4g VG8gdW5zdWJzY3JpYmUgZnJvbSB0aGlzIGdyb3VwIGFuZCBzdG9wIHJlY2VpdmluZyBlbWFpbHMg ZnJvbSBpdCwgc2VuZCBhbiBlbWFpbCB0byBrYXNhbi1kZXYrdW5zdWJzY3JpYmVAZ29vZ2xlZ3Jv dXBzLmNvbS4KPiBUbyB2aWV3IHRoaXMgZGlzY3Vzc2lvbiBvbiB0aGUgd2ViIHZpc2l0IGh0dHBz Oi8vZ3JvdXBzLmdvb2dsZS5jb20vZC9tc2dpZC9rYXNhbi1kZXYvOTJmMzAyOWYzNjQ3YWIzNTU0 NTBlZDVjODI1MmJhZDhjZmFlMWUwOS4xNjQwMDM2MDUxLmdpdC5hbmRyZXlrbnZsJTQwZ29vZ2xl LmNvbS4KCgoKLS0gCkFsZXhhbmRlciBQb3RhcGVua28KU29mdHdhcmUgRW5naW5lZXIKCkdvb2ds ZSBHZXJtYW55IEdtYkgKRXJpa2EtTWFubi1TdHJhw59lLCAzMwo4MDYzNiBNw7xuY2hlbgoKR2Vz Y2jDpGZ0c2bDvGhyZXI6IFBhdWwgTWFuaWNsZSwgSGFsaW1haCBEZUxhaW5lIFByYWRvClJlZ2lz dGVyZ2VyaWNodCB1bmQgLW51bW1lcjogSGFtYnVyZywgSFJCIDg2ODkxClNpdHogZGVyIEdlc2Vs bHNjaGFmdDogSGFtYnVyZwoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxpc3QKbGludXgtYXJtLWtlcm5lbEBs aXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlz dGluZm8vbGludXgtYXJtLWtlcm5lbAo=