linux-kernel - Re: [PATCH v4 03/36] mm/slub: Mark slab_free_freelist_hook() __always

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Message-ID: <CAJuCfpE_=A3H+FKwHeu-XLX5rDCqrV8dUT40=EVm4w_q8A=EwQ@mail.gmail.com>
Date: Mon, 26 Feb 2024 08:09:40 -0800
From: Suren Baghdasaryan <surenb@...gle.com>
To: Pasha Tatashin <pasha.tatashin@...een.com>
Cc: Vlastimil Babka <vbabka@...e.cz>, Andrew Morton <akpm@...ux-foundation.org>, 
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Subject: Re: [PATCH v4 03/36] mm/slub: Mark slab_free_freelist_hook() __always_inline

On Mon, Feb 26, 2024 at 7:21 AM Pasha Tatashin
<pasha.tatashin@...een.com> wrote:
>
>
>
> On Mon, Feb 26, 2024, 9:31 AM Vlastimil Babka <vbabka@...e.cz> wrote:
>>
>> On 2/24/24 03:02, Suren Baghdasaryan wrote:
>> > On Wed, Feb 21, 2024 at 1:16 PM Pasha Tatashin
>> > <pasha.tatashin@...een.com> wrote:
>> >>
>> >> On Wed, Feb 21, 2024 at 2:41 PM Suren Baghdasaryan <surenb@...gle.com> wrote:
>> >> >
>> >> > From: Kent Overstreet <kent.overstreet@...ux.dev>
>> >> >
>> >> > It seems we need to be more forceful with the compiler on this one.
>> >> > This is done for performance reasons only.
>> >> >
>> >> > Signed-off-by: Kent Overstreet <kent.overstreet@...ux.dev>
>> >> > Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
>> >> > Reviewed-by: Kees Cook <keescook@...omium.org>
>> >> > ---
>> >> >  mm/slub.c | 2 +-
>> >> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >> >
>> >> > diff --git a/mm/slub.c b/mm/slub.c
>> >> > index 2ef88bbf56a3..d31b03a8d9d5 100644
>> >> > --- a/mm/slub.c
>> >> > +++ b/mm/slub.c
>> >> > @@ -2121,7 +2121,7 @@ bool slab_free_hook(struct kmem_cache *s, void *x, bool init)
>> >> >         return !kasan_slab_free(s, x, init);
>> >> >  }
>> >> >
>> >> > -static inline bool slab_free_freelist_hook(struct kmem_cache *s,
>> >> > +static __always_inline bool slab_free_freelist_hook(struct kmem_cache *s,
>> >>
>> >> __fastpath_inline seems to me more appropriate here. It prioritizes
>> >> memory vs performance.
>> >
>> > Hmm. AFAIKT this function is used only in one place and we do not add
>> > any additional users, so I don't think changing to __fastpath_inline
>> > here would gain us anything.
>
>
> For consistency __fastpath_inline makes more sense, but I am ok with or without this change.

Ok, I'll update in the next revision. Thanks!

>
> Reviewed-by: Pasha Tatashin <pasha.tatashin@...een.com>
>
>>
>> It would have been more future-proof and self-documenting. But I don't insist.
>>
>> Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
>>
>> >>
>> >> >                                            void **head, void **tail,
>> >> >                                            int *cnt)
>> >> >  {
>> >> > --
>> >> > 2.44.0.rc0.258.g7320e95886-goog
>> >> >
>>