linux-kernel - Re: kernel/futex/core.c:505:38: sparse: sparse: cast removes address space '_

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Message-ID: <20260113115946.L49jwJMx@linutronix.de>
Date: Tue, 13 Jan 2026 12:59:46 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Peter Zijlstra <peterz@...radead.org>
Cc: kernel test robot <lkp@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: kernel/futex/core.c:505:38: sparse: sparse: cast removes address
 space '__user' of expression

On 2026-01-13 19:22:40 [+0800], kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   b71e635feefc852405b14620a7fc58c4c80c0f73
> commit: cec199c5e39bde7191a08087cc3d002ccfab31ff futex: Implement FUTEX2_NUMA
> date:   9 months ago
> config: arm64-randconfig-r123-20260113 (https://download.01.org/0day-ci/archive/20260113/202601131901.j7WJ9OeZ-lkp@intel.com/config)
> compiler: clang version 16.0.6 (https://github.com/llvm/llvm-project 7cbf1a2591520c2491aa35339f227775f4d3adf6)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260113/202601131901.j7WJ9OeZ-lkp@intel.com/reproduce)
…
>sparse warnings: (new ones prefixed by >>)
>>> kernel/futex/core.c:505:38: sparse: sparse: cast removes address space '__user' of expression
>>> kernel/futex/core.c:505:51: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected unsigned int [noderef] [usertype] __user *naddr @@     got void * @@
>   kernel/futex/core.c:505:51: sparse:     expected unsigned int [noderef] [usertype] __user *naddr
>   kernel/futex/core.c:505:51: sparse:     got void *
>   kernel/futex/core.c:894:9: sparse: sparse: context imbalance in 'futex_q_lockptr_lock' - wrong count at exit
…
>  > 505			u32 __user *naddr = (void *)uaddr + size / 2;

[ ] I (PeterZ) have it fixed, will post soon
[ ] Fix it for me, I'm saving the world atm
[ ] Ignore it because of $reasonable_reason

Sebastian