diff mbox series

[06/31] mm: clarify __GFP_ZEROTAGS comment

Message ID	4f6d3dd6f1ab9d7774c96ca0ad6d8cabebf0914b.1638308023.git.andreyknvl@google.com (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> From: andrey.konovalov@linux.dev To: Marco Elver <elver@google.com>, Alexander Potapenko <glider@google.com>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Peter Collingbourne <pcc@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com>, Dmitry Vyukov <dvyukov@google.com>, Andrey Ryabinin <aryabinin@virtuozzo.com>, kasan-dev@googlegroups.com, Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org, Evgenii Stepanov <eugenis@google.com>, linux-kernel@vger.kernel.org, Andrey Konovalov <andreyknvl@google.com> Subject: [PATCH 06/31] mm: clarify __GFP_ZEROTAGS comment Date: Tue, 30 Nov 2021 22:41:28 +0100 Message-Id: <4f6d3dd6f1ab9d7774c96ca0ad6d8cabebf0914b.1638308023.git.andreyknvl@google.com> In-Reply-To: <cover.1638308023.git.andreyknvl@google.com> References: <cover.1638308023.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS \| expand [00/31] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS [01/31] kasan, page_alloc: deduplicate should_skip_kasan_poison [02/31] kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages [03/31] kasan, page_alloc: merge kasan_free_pages into free_pages_prepare [04/31] kasan, page_alloc: simplify kasan_poison_pages call site [05/31] kasan, page_alloc: init memory of skipped pages on free [06/31] mm: clarify __GFP_ZEROTAGS comment [07/31] kasan: only apply __GFP_ZEROTAGS when memory is zeroed [08/31] kasan, page_alloc: refactor init checks in post_alloc_hook [09/31] kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook [10/31] kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook [11/31] kasan, page_alloc: move SetPageSkipKASanPoison in post_alloc_hook [12/31] kasan, page_alloc: move kernel_init_free_pages in post_alloc_hook [13/31] kasan, page_alloc: simplify kasan_unpoison_pages call site [14/31] kasan: clean up metadata byte definitions [15/31] kasan: define KASAN_VMALLOC_INVALID for SW_TAGS [16/31] kasan, x86, arm64, s390: rename functions for modules shadow [17/31] kasan, vmalloc: drop outdated VM_KASAN comment [18/31] kasan: reorder vmalloc hooks [19/31] kasan: add wrappers for vmalloc hooks [20/31] kasan, vmalloc: reset tags in vmalloc functions [21/31] kasan, fork: don't tag stacks allocated with vmalloc [22/31] kasan, vmalloc: add vmalloc support to SW_TAGS [23/31] kasan, arm64: allow KASAN_VMALLOC with SW_TAGS [24/31] kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged [25/31] kasan, vmalloc: don't unpoison VM_ALLOC pages before mapping [26/31] kasan, page_alloc: allow skipping unpoisoning for HW_TAGS [27/31] kasan, vmalloc: add vmalloc support to HW_TAGS [28/31] kasan: add kasan.vmalloc command line flag [29/31] kasan, arm64: allow KASAN_VMALLOC with HW_TAGS [30/31] kasan: documentation updates [31/31] kasan: improve vmalloc tests

Commit Message

andrey.konovalov@linux.dev Nov. 30, 2021, 9:41 p.m. UTC

From: Andrey Konovalov <andreyknvl@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.

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 mbox series

Patch

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index b976c4177299..dddd7597689f 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -232,8 +232,8 @@  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