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Thu, 23 Nov 2023 10:48:17 -0800 (PST) MIME-Version: 1.0 References: <9752c5fc4763e7533a44a7c9368f056c47b52f34.1699297309.git.andreyknvl@google.com> In-Reply-To: From: Marco Elver Date: Thu, 23 Nov 2023 19:47:40 +0100 Message-ID: Subject: Re: [PATCH RFC 14/20] mempool: introduce mempool_use_prealloc_only To: Andrey Konovalov Cc: andrey.konovalov@linux.dev, Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, Evgenii Stepanov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: D5A40100005 X-Rspam-User: X-Stat-Signature: t4kacnkrucwxgqtgri36ejhsa4ztnx6c X-Rspamd-Server: rspam01 X-HE-Tag: 1700765298-943593 X-HE-Meta: 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 qw87zwEa NUpOsEYxESc1QvOKviF+8zHOKIiP6DQFB88X+F8rrn4ql71MROi1MPZgY5sXtt5h8tbF8euIhotRmPPXWKxq/gWkzfllNo+G9FZgMcj0Vx8halDSWV3YbQ/sNeE9XO33TI9N5WCGSuW+xwW+7iBJRWojLzBrT4+McUJLJQX+5GQ+7JzZ3co1Zjy6cw/UScDJDhMs59ihvMjUi2M0XKtTvDs2tTadi80l3UeyCFYVODagaxw6lbNQdJN6TsWyZdagDxDyOmpHnPktHUVX+6Ky20EBsNVeFeJEC+sZiVvHvZZZmRo2cDea6aofnnknIHcuK9W7Bxshx4ux+tP4CgvKFm9YjloULrcWZeEjNENTNtnIc7iMcKxmqwfe+9gdBsjs379CfNqUj1zbJ5m4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 23 Nov 2023 at 19:06, Andrey Konovalov wrote= : > > On Wed, Nov 22, 2023 at 6:21=E2=80=AFPM Marco Elver wr= ote: > > > > On Mon, Nov 06, 2023 at 09:10PM +0100, andrey.konovalov@linux.dev wrote= : > > > From: Andrey Konovalov > > > > > > Introduce a new mempool_use_prealloc_only API that tells the mempool = to > > > only use the elements preallocated during the mempool's creation and = to > > > not attempt allocating new ones. > > > > > > This API is required to test the KASAN poisoning/unpoisoning functina= lity > > > in KASAN tests, but it might be also useful on its own. > > > > > > Signed-off-by: Andrey Konovalov > > > --- > > > include/linux/mempool.h | 2 ++ > > > mm/mempool.c | 27 ++++++++++++++++++++++++--- > > > 2 files changed, 26 insertions(+), 3 deletions(-) > > > > > > diff --git a/include/linux/mempool.h b/include/linux/mempool.h > > > index 4aae6c06c5f2..822adf1e7567 100644 > > > --- a/include/linux/mempool.h > > > +++ b/include/linux/mempool.h > > > @@ -18,6 +18,7 @@ typedef struct mempool_s { > > > int min_nr; /* nr of elements at *elements */ > > > int curr_nr; /* Current nr of elements at *elements = */ > > > void **elements; > > > + bool use_prealloc_only; /* Use only preallocated elements */ > > > > This increases the struct size from 56 to 64 bytes (64 bit arch). > > mempool_t is embedded in lots of other larger structs, and this may > > result in some unwanted bloat. > > > > Is there a way to achieve the same thing without adding a new bool to > > the mempool struct? > > We could split out the part of mempool_alloc that uses preallocated > elements without what waiting part and expose it in another API > function named something like mempool_alloc_preallocated. Would that > be better? Yes, that might be better. As long as other users of mempool (esp if KASAN is disabled) are unaffected then it should be fine.