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mm: clarify __GFP_ZEROTAGS comment

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__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.

Link: https://lkml.kernel.org/r/cdffde013973c5634a447513e10ec0d21e8eee29.1643047180.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2022-03-24 18:10:22 -07:00 committed by Linus Torvalds
parent 487a32ec24
commit c82ce3195f
1 changed files with 4 additions and 2 deletions
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6
include/linux/gfp.h
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@ -232,8 +232,10 @@ 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). This flag is
* intended for optimization: setting memory tags at the same time as zeroing
* memory has minimal additional performace impact.
*
* %__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