linux-kernel - kernel/events/core.c:7429 perf_virt_to_phys() warn: always true condition '(virt >= 0) => (0-u64max >= 0)'

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Message-ID: <202305071045.e0D7M8pZ-lkp@intel.com>
Date:   Sun, 7 May 2023 10:11:31 +0800
From:   kernel test robot <lkp@...el.com>
To:     Yimin Gu <ustcymgu@...il.com>
Cc:     oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Palmer Dabbelt <palmer@...osinc.com>,
        Jesse Taube <Mr.Bossman075@...il.com>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Conor Dooley <conor.dooley@...rochip.com>
Subject: kernel/events/core.c:7429 perf_virt_to_phys() warn: always true
 condition '(virt >= 0) => (0-u64max >= 0)'

Hi Yimin,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   fc4354c6e5c21257cf4a50b32f7c11c7d65c55b3
commit: b5e2c507b06c9d36411845149162a804ae7b04a9 riscv: Kconfig: Allow RV32 to build with no MMU
date:   6 weeks ago
config: riscv-randconfig-m041-20230507 (https://download.01.org/0day-ci/archive/20230507/202305071045.e0D7M8pZ-lkp@intel.com/config)
compiler: riscv32-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202305071045.e0D7M8pZ-lkp@intel.com/

New smatch warnings:
kernel/events/core.c:7429 perf_virt_to_phys() warn: always true condition '(virt >= 0) => (0-u64max >= 0)'

Old smatch warnings:
arch/riscv/include/asm/atomic.h:204 arch_atomic_fetch_add_unless() warn: inconsistent indenting

vim +7429 kernel/events/core.c

5622f295b53fb6 kernel/perf_counter.c Markus Metzger   2009-09-15  7418  
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7419  static u64 perf_virt_to_phys(u64 virt)
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7420  {
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7421  	u64 phys_addr = 0;
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7422  
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7423  	if (!virt)
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7424  		return 0;
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7425  
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7426  	if (virt >= TASK_SIZE) {
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7427  		/* If it's vmalloc()d memory, leave phys_addr as 0 */
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7428  		if (virt_addr_valid((void *)(uintptr_t)virt) &&
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28 @7429  		    !(virt >= VMALLOC_START && virt < VMALLOC_END))
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7430  			phys_addr = (u64)virt_to_phys((void *)(uintptr_t)virt);
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7431  	} else {
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7432  		/*
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7433  		 * Walking the pages tables for user address.
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7434  		 * Interrupts are disabled, so it prevents any tear down
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7435  		 * of the page tables.
dadbb612f6e50b kernel/events/core.c  Souptick Joarder 2020-06-07  7436  		 * Try IRQ-safe get_user_page_fast_only first.
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7437  		 * If failed, leave phys_addr as 0.
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7438  		 */
d3296fb372bf74 kernel/events/core.c  Jiri Olsa        2020-04-07  7439  		if (current->mm != NULL) {
4716023a8f6a0f kernel/events/core.c  Greg Thelen      2021-11-10  7440  			struct page *p;
4716023a8f6a0f kernel/events/core.c  Greg Thelen      2021-11-10  7441  
d3296fb372bf74 kernel/events/core.c  Jiri Olsa        2020-04-07  7442  			pagefault_disable();
4716023a8f6a0f kernel/events/core.c  Greg Thelen      2021-11-10  7443  			if (get_user_page_fast_only(virt, 0, &p)) {
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7444  				phys_addr = page_to_phys(p) + virt % PAGE_SIZE;
4716023a8f6a0f kernel/events/core.c  Greg Thelen      2021-11-10  7445  				put_page(p);
4716023a8f6a0f kernel/events/core.c  Greg Thelen      2021-11-10  7446  			}
d3296fb372bf74 kernel/events/core.c  Jiri Olsa        2020-04-07  7447  			pagefault_enable();
d3296fb372bf74 kernel/events/core.c  Jiri Olsa        2020-04-07  7448  		}
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7449  	}
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7450  
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7451  	return phys_addr;
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7452  }
fc7ce9c74c3ad2 kernel/events/core.c  Kan Liang        2017-08-28  7453  

:::::: The code at line 7429 was first introduced by commit
:::::: fc7ce9c74c3ad232b084d80148654f926d01ece7 perf/core, x86: Add PERF_SAMPLE_PHYS_ADDR

:::::: TO: Kan Liang <kan.liang@...el.com>
:::::: CC: Ingo Molnar <mingo@...nel.org>

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests