From: Alexander Potapenko <glider@google.com>
To: andrey.konovalov@linux.dev
Cc: Marco Elver <elver@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
kasan-dev <kasan-dev@googlegroups.com>,
Linux Memory Management List <linux-mm@kvack.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Peter Collingbourne <pcc@google.com>,
Evgenii Stepanov <eugenis@google.com>,
LKML <linux-kernel@vger.kernel.org>,
Andrey Konovalov <andreyknvl@google.com>
Subject: Re: [PATCH mm v4 07/39] mm: clarify __GFP_ZEROTAGS comment
Date: Tue, 21 Dec 2021 10:16:41 +0100 [thread overview]
Message-ID: <CAG_fn=XcPT=e6zmm-B4KQPLujpuC9D+hTbJEsua31onzopDT5g@mail.gmail.com> (raw)
In-Reply-To: <92f3029f3647ab355450ed5c8252bad8cfae1e09.1640036051.git.andreyknvl@google.com>
On Mon, Dec 20, 2021 at 10:59 PM <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
>
> __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 <andreyknvl@google.com>
> ---
> 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 itself
> + * 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 poisoned
> * on deallocation. Typically used for userspace pages. Currently only has an
> --
> 2.25.1
>
> --
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--
Alexander Potapenko
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next prev parent reply other threads:[~2021-12-21 9:17 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 21:58 [PATCH mm v4 00/39] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 01/39] kasan, page_alloc: deduplicate should_skip_kasan_poison andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 02/39] kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 03/39] kasan, page_alloc: merge kasan_free_pages into free_pages_prepare andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 04/39] kasan, page_alloc: simplify kasan_poison_pages call site andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 05/39] kasan, page_alloc: init memory of skipped pages on free andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 06/39] kasan: drop skip_kasan_poison variable in free_pages_prepare andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 07/39] mm: clarify __GFP_ZEROTAGS comment andrey.konovalov
2021-12-21 9:16 ` Alexander Potapenko [this message]
2021-12-30 19:11 ` Andrey Konovalov
2021-12-20 21:58 ` [PATCH mm v4 08/39] kasan: only apply __GFP_ZEROTAGS when memory is zeroed andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 09/39] kasan, page_alloc: refactor init checks in post_alloc_hook andrey.konovalov
2021-12-20 21:58 ` [PATCH mm v4 10/39] kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 11/39] kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 12/39] kasan, page_alloc: move SetPageSkipKASanPoison " andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 13/39] kasan, page_alloc: move kernel_init_free_pages " andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 14/39] kasan, page_alloc: rework kasan_unpoison_pages call site andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 15/39] kasan: clean up metadata byte definitions andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 16/39] kasan: define KASAN_VMALLOC_INVALID for SW_TAGS andrey.konovalov
2021-12-21 9:23 ` Alexander Potapenko
2021-12-20 21:59 ` [PATCH mm v4 17/39] kasan, x86, arm64, s390: rename functions for modules shadow andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 18/39] kasan, vmalloc: drop outdated VM_KASAN comment andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 19/39] kasan: reorder vmalloc hooks andrey.konovalov
2021-12-20 21:59 ` [PATCH mm v4 20/39] kasan: add wrappers for " andrey.konovalov
2021-12-21 14:21 ` Alexander Potapenko
2021-12-20 21:59 ` [PATCH mm v4 21/39] kasan, vmalloc: reset tags in vmalloc functions andrey.konovalov
2021-12-20 22:01 ` [PATCH mm v4 22/39] kasan, fork: reset pointer tags of vmapped stacks andrey.konovalov
2021-12-21 15:11 ` Alexander Potapenko
2021-12-20 22:01 ` [PATCH mm v4 23/39] kasan, arm64: " andrey.konovalov
2021-12-20 22:01 ` [PATCH mm v4 24/39] kasan, vmalloc: add vmalloc tagging for SW_TAGS andrey.konovalov
2021-12-20 22:01 ` [PATCH mm v4 25/39] kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged andrey.konovalov
2021-12-20 22:01 ` [PATCH mm v4 26/39] kasan, vmalloc: unpoison VM_ALLOC pages after mapping andrey.konovalov
2021-12-21 11:50 ` Alexander Potapenko
2021-12-20 22:01 ` [PATCH mm v4 27/39] kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS andrey.konovalov
2021-12-20 22:02 ` [PATCH mm v4 28/39] kasan, page_alloc: allow skipping unpoisoning for HW_TAGS andrey.konovalov
2021-12-21 12:04 ` Marco Elver
2021-12-30 19:11 ` Andrey Konovalov
2021-12-21 12:14 ` Marco Elver
2021-12-21 12:19 ` Marco Elver
2021-12-20 22:02 ` [PATCH mm v4 29/39] kasan, page_alloc: allow skipping memory init " andrey.konovalov
2021-12-21 12:11 ` Marco Elver
2021-12-30 19:11 ` Andrey Konovalov
2021-12-21 12:30 ` Marco Elver
2021-12-30 19:11 ` Andrey Konovalov
2021-12-20 22:02 ` [PATCH mm v4 30/39] kasan, vmalloc: add vmalloc tagging " andrey.konovalov
2021-12-20 22:02 ` [PATCH mm v4 31/39] kasan, vmalloc: only tag normal vmalloc allocations andrey.konovalov
2021-12-20 22:02 ` [PATCH mm v4 32/39] kasan, arm64: don't tag executable " andrey.konovalov
2021-12-20 22:05 ` Andrey Konovalov
2021-12-22 11:11 ` Catalin Marinas
2021-12-20 22:02 ` [PATCH mm v4 33/39] kasan: mark kasan_arg_stacktrace as __initdata andrey.konovalov
2021-12-20 22:02 ` [PATCH mm v4 34/39] kasan: simplify kasan_init_hw_tags andrey.konovalov
2021-12-20 22:02 ` [PATCH mm v4 35/39] kasan: add kasan.vmalloc command line flag andrey.konovalov
2021-12-21 14:43 ` Alexander Potapenko
2021-12-30 19:11 ` Andrey Konovalov
2021-12-20 22:03 ` [PATCH mm v4 36/39] kasan: allow enabling KASAN_VMALLOC and SW/HW_TAGS andrey.konovalov
2021-12-20 22:03 ` [PATCH mm v4 37/39] arm64: select KASAN_VMALLOC for SW/HW_TAGS modes andrey.konovalov
2021-12-20 22:03 ` [PATCH mm v4 38/39] kasan: documentation updates andrey.konovalov
2021-12-20 22:03 ` [PATCH mm v4 39/39] kasan: improve vmalloc tests andrey.konovalov
2021-12-22 7:00 ` [PATCH mm v4 00/39] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS Marco Elver
2021-12-30 19:11 ` Andrey Konovalov
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