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b=EMx2BUw/mk9z5LR2kM5oqWedT160RYUpYEAIINZtWONcWcjqPg7BbXE56Qy6PEFam er/CkcI7E6VOBemyixM11nwUvcQ1XKBMiAncHZP91YpvllIrSPf8H/cLAQ/lpp332A Qtv+93+m9pamvx79iyt3kcinjJoV6MKxvr/VP/QOi3kTzsHgyO8811a6f7qByR/fyG knhMjDWoSOMdbwmEIkwrIlJXT6qKJJW/UOrunSUKjSy1TeTUI/iVnJy+lLsWabJA8k 4LxhuCGGnn23LXaza2y8FWpdBKPmMJzpXXJQ92qg6AOGPRlXY5F6M+6B332VUPtaom 2qZ+OGzzcdjTw== Message-ID: <602bdc5f-e9fa-4ed5-a009-03af860d31a6@kernel.org> Date: Mon, 31 Aug 2026 05:02:54 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] serial: core: replace get_zeroed_page() with kzalloc() To: "Mike Rapoport (Microsoft)" , Greg Kroah-Hartman Cc: Andrew Morton , David Hildenbrand , Matthew Wilcox , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-serial@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <20260830-tty-v1-0-0cbe6170649b@kernel.org> <20260830-tty-v1-2-0cbe6170649b@kernel.org> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; keydata= xsFNBE6S54YBEACzzjLwDUbU5elY4GTg/NdotjA0jyyJtYI86wdKraekbNE0bC4zV+ryvH4j rrcDwGs6tFVrAHvdHeIdI07s1iIx5R/ndcHwt4fvI8CL5PzPmn5J+h0WERR5rFprRh6axhOk rSD5CwQl19fm4AJCS6A9GJtOoiLpWn2/IbogPc71jQVrupZYYx51rAaHZ0D2KYK/uhfc6neJ i0WqPlbtIlIrpvWxckucNu6ZwXjFY0f3qIRg3Vqh5QxPkojGsq9tXVFVLEkSVz6FoqCHrUTx wr+aw6qqQVgvT/McQtsI0S66uIkQjzPUrgAEtWUv76rM4ekqL9stHyvTGw0Fjsualwb0Gwdx ReTZzMgheAyoy/umIOKrSEpWouVoBt5FFSZUyjuDdlPPYyPav+hpI6ggmCTld3u2hyiHji2H cDpcLM2LMhlHBipu80s9anNeZhCANDhbC5E+NZmuwgzHBcan8WC7xsPXPaiZSIm7TKaVoOcL 9tE5aN3jQmIlrT7ZUX52Ff/hSdx/JKDP3YMNtt4B0cH6ejIjtqTd+Ge8sSttsnNM0CQUkXps w98jwz+Lxw/bKMr3NSnnFpUZaxwji3BC9vYyxKMAwNelBCHEgS/OAa3EJoTfuYOK6wT6nadm YqYjwYbZE5V/SwzMbpWu7Jwlvuwyfo5mh7w5iMfnZE+vHFwp/wARAQABzSFKaXJpIFNsYWJ5 IDxqaXJpc2xhYnlAa2VybmVsLm9yZz7CwXcEEwEIACEFAlW3RUwCGwMFCwkIBwIGFQgJCgsC BBYCAwECHgECF4AACgkQvSWxBAa0cEnVTg//TQpdIAr8Tn0VAeUjdVIH9XCFw+cPSU+zMSCH eCZoA/N6gitEcnvHoFVVM7b3hK2HgoFUNbmYC0RdcSc80pOF5gCnACSP9XWHGWzeKCARRcQR 4s5YD8I4VV5hqXcKo2DFAtIOVbHDW+0okOzcecdasCakUTr7s2fXz97uuoc2gIBB7bmHUGAH XQXHvdnCLjDjR+eJN+zrtbqZKYSfj89s/ZHn5Slug6w8qOPT1sVNGG+eWPlc5s7XYhT9z66E l5C0rG35JE4PhC+tl7BaE5IwjJlBMHf/cMJxNHAYoQ1hWQCKOfMDQ6bsEr++kGUCbHkrEFwD UVA72iLnnnlZCMevwE4hc0zVhseWhPc/KMYObU1sDGqaCesRLkE3tiE7X2cikmj/qH0CoMWe gjnwnQ2qVJcaPSzJ4QITvchEQ+tbuVAyvn9H+9MkdT7b7b2OaqYsUP8rn/2k1Td5zknUz7iF oJ0Z9wPTl6tDfF8phaMIPISYrhceVOIoL+rWfaikhBulZTIT5ihieY9nQOw6vhOfWkYvv0Dl o4GRnb2ybPQpfEs7WtetOsUgiUbfljTgILFw3CsPW8JESOGQc0Pv8ieznIighqPPFz9g+zSu Ss/rpcsqag5n9rQp/H3WW5zKUpeYcKGaPDp/vSUovMcjp8USIhzBBrmI7UWAtuedG9prjqfO wU0ETpLnhgEQAM+cDWLL+Wvc9cLhA2OXZ/gMmu7NbYKjfth1UyOuBd5emIO+d4RfFM02XFTI t4MxwhAryhsKQQcA4iQNldkbyeviYrPKWjLTjRXT5cD2lpWzr+Jx7mX7InV5JOz1Qq+P+nJW YIBjUKhI03ux89p58CYil24Zpyn2F5cX7U+inY8lJIBwLPBnc9Z0An/DVnUOD+0wIcYVnZAK DiIXODkGqTg3fhZwbbi+KAhtHPFM2fGw2VTUf62IHzV+eBSnamzPOBc1XsJYKRo3FHNeLuS8 f4wUe7bWb9O66PPFK/RkeqNX6akkFBf9VfrZ1rTEKAyJ2uqf1EI1olYnENk4+00IBa+BavGQ 8UW9dGW3nbPrfuOV5UUvbnsSQwj67pSdrBQqilr5N/5H9z7VCDQ0dhuJNtvDSlTf2iUFBqgk 3smln31PUYiVPrMP0V4ja0i9qtO/TB01rTfTyXTRtqz53qO5dGsYiliJO5aUmh8swVpotgK4 /57h3zGsaXO9PGgnnAdqeKVITaFTLY1ISg+Ptb4KoliiOjrBMmQUSJVtkUXMrCMCeuPDGHo7 39Xc75lcHlGuM3yEB//htKjyprbLeLf1y4xPyTeeF5zg/0ztRZNKZicgEmxyUNBHHnBKHQxz 1j+mzH0HjZZtXjGu2KLJ18G07q0fpz2ZPk2D53Ww39VNI/J9ABEBAAHCwV8EGAECAAkFAk6S 54YCGwwACgkQvSWxBAa0cEk3tRAAgO+DFpbyIa4RlnfpcW17AfnpZi9VR5+zr496n2jH/1ld wRO/S+QNSA8qdABqMb9WI4BNaoANgcg0AS429Mq0taaWKkAjkkGAT7mD1Q5PiLr06Y/+Kzdr 90eUVneqM2TUQQbK+Kh7JwmGVrRGNqQrDk+gRNvKnGwFNeTkTKtJ0P8jYd7P1gZb9Fwj9YLx jhn/sVIhNmEBLBoI7PL+9fbILqJPHgAwW35rpnq4f/EYTykbk1sa13Tav6btJ+4QOgbcezWI wZ5w/JVfEJW9JXp3BFAVzRQ5nVrrLDAJZ8Y5ioWcm99JtSIIxXxt9FJaGc1Bgsi5K/+dyTKL wLMJgiBzbVx8G+fCJJ9YtlNOPWhbKPlrQ8+AY52Aagi9WNhe6XfJdh5g6ptiOILm330mkR4g W6nEgZVyIyTq3ekOuruftWL99qpP5zi+eNrMmLRQx9iecDNgFr342R9bTDlb1TLuRb+/tJ98 f/bIWIr0cqQmqQ33FgRhrG1+Xml6UXyJ2jExmlO8JljuOGeXYh6ZkIEyzqzffzBLXZCujlYQ DFXpyMNVJ2ZwPmX2mWEoYuaBU0JN7wM+/zWgOf2zRwhEuD3A2cO2PxoiIfyUEfB9SSmffaK/ S4xXoB6wvGENZ85Hg37C7WDNdaAt6Xh2uQIly5grkgvWppkNy4ZHxE+jeNsU7tg= In-Reply-To: <20260830-tty-v1-2-0cbe6170649b@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 125CEA0008 X-Stat-Signature: k76eifdsg3arkjpa9nrjb4a8d93cz777 X-HE-Tag: 1788145378-516598 X-HE-Meta: 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 vqSF3CqW Lv9wWLcwRYS2xm7HGrbhLpnwFPjPWPZmd3fuQz5UT6JBGg8jteftzpIu2WDS+HyPRnpnAavUusArz+dQLDVn+wl6qpdONYldwnqFd7/xkYs1kbfDjd/N4MvpUC0hajA2D5xn8Sn5YsqcwnZbJSP6m8WrnpD9SxnFxrRWc1jTjQCrdhSeY8U2Z1qZoxH/zMah32c8uAwgtGogmpQYYwnksvktXK/hU/krSEtAyQfEuokXyXkBu5KTKuRRycJ5YbwFR+yJX9w1SVLSXi6fR5byJqBh0K1iGL/nD0UNCmBesRxKEZwppcVGLCIXNzioHnl5SYSSRH7xHEDEeELdqdu+279nFGWcFNuNQrvnk Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 30. 08. 26, 9:49, Mike Rapoport (Microsoft) wrote: > uart_alloc_xmit_buf() allocates the transmit buffer of a serial port. The > buffer only backs the port's kfifo, the data being sent is copied in and > out of it. > > This buffer can be allocated with kmalloc() as there's nothing special > about it to go directly to the page allocator. > > kmalloc() provides a better API that does not require ugly casts and > kfree() does not need to know the size of the freed object. > > Performance difference between kmalloc() and __get_free_pages() is not > measurable as both allocators take an object/page from a per-CPU list for > fast path allocations. > > For the slow path the performance is anyway determined by the amount of > reclaim involved rather than by what allocator is used. > > While on it, make the local variable holding the buffer a pointer to get > rid of the casts. > > Replace use of get_zeroed_page() with kzalloc() and free_page() with > kfree(). > > Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com > Assisted-by: copilot:claude-opus > Signed-off-by: Mike Rapoport (Microsoft) > --- > drivers/tty/serial/serial_core.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index 95774b0f1484..f12ce7d190fe 100644 > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -247,29 +247,29 @@ static int uart_alloc_xmit_buf(struct tty_port *port) > struct uart_state *state = container_of(port, struct uart_state, port); > struct uart_port *uport; > unsigned long flags; > - unsigned long page; 1: > + unsigned char *buf; > > /* > * Initialise and allocate the transmit and temporary > * buffer. > */ > - page = get_zeroed_page(GFP_KERNEL); > - if (!page) > + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); > + if (!buf) > return -ENOMEM; > > uport = uart_port_ref_lock(state, &flags); > if (!state->port.xmit_buf) { > - state->port.xmit_buf = (unsigned char *)page; > + state->port.xmit_buf = buf; xmit_buf is u8 *. This uchar was omitted when I was changing the type back then. Could you use the right type at 1b now? thanks, -- js suse labs