linux-kernel - Re: [ANNOUNCE] 6.6.12-rt20

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Date: Wed, 24 Jan 2024 10:48:43 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Clark Williams <williams@...hat.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
	linux-rt-users <linux-rt-users@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Carsten Emde <C.Emde@...dl.org>, John Kacur <jkacur@...hat.com>,
	Daniel Wagner <daniel.wagner@...e.com>,
	Tom Zanussi <tom.zanussi@...ux.intel.com>,
	Pavel Machek <pavel@...x.de>,
	Joseph Salisbury <joseph.salisbury@...onical.com>
Subject: Re: [ANNOUNCE] 6.6.12-rt20

On 2024-01-18 20:59:45 [-0000], Clark Williams wrote:
> Hello RT-list!
Hi Clark,

> I'm pleased to announce the 6.6.12-rt20 stable release.

I've been looking over it and it looks okay. Then I compared how it
would do it vs your outcome and noticed this:

--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -575,12 +575,6 @@ static int check_unaligned_access(void *param)
 	if (per_cpu(misaligned_access_speed, cpu) != RISCV_HWPROBE_MISALIGNED_UNKNOWN)
 		return;
 
-	page = alloc_pages(GFP_NOWAIT, get_order(MISALIGNED_BUFFER_SIZE));
-	if (!page) {
-		pr_warn("Can't alloc pages to measure memcpy performance");
-		return;
-	}
-
 	/* Make an unaligned destination buffer. */
 	dst = (void *)((unsigned long)page_address(page) | 0x1);
 	/* Unalign src as well, but differently (off by 1 + 2 = 3). */

You shouldn't allocate that page. Nobody will free it, that page is
passed via an argument now. Please drop hunk.

While at it, do you think you can drop patch
   preempt-Put-preempt_enable-within-an-instrumentation.patch

or revert commit
   c15abad8f7159 ("preempt: Put preempt_enable() within an instrumentation*() section.")

I've been looking over it and it is fixed as of v6.6 so this patch is no
longer needed.

> Enjoy!
> Clark

Sebastian