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Message-ID: <aLgXVIxyFpvZ9PU7@devbig569.cln6.facebook.com>
Date: Wed, 3 Sep 2025 03:24:20 -0700
From: Yueyang Pan <pyyjason@...il.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: kernel test robot <lkp@...el.com>,
Suren Baghdasaryan <surenb@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Michal Hocko <mhocko@...e.com>,
Brendan Jackman <jackmanb@...gle.com>,
Johannes Weiner <hannes@...xchg.org>, Zi Yan <ziy@...dia.com>,
Vishal Moola <vishal.moola@...il.com>,
Shakeel Butt <shakeel.butt@...ux.dev>,
Usama Arif <usamaarif642@...il.com>, oe-kbuild-all@...ts.linux.dev,
Linux Memory Management List <linux-mm@...ck.org>,
kernel-team@...a.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] mm/show_mem: Add trylock while printing alloc info
On Wed, Sep 03, 2025 at 12:16:45PM +0200, Vlastimil Babka wrote:
> On 9/3/25 11:47, kernel test robot wrote:
> > Hi Yueyang,
> >
> > kernel test robot noticed the following build warnings:
> >
> > [auto build test WARNING on akpm-mm/mm-everything]
> >
> > url: https://github.com/intel-lab-lkp/linux/commits/Yueyang-Pan/mm-show_mem-Dump-the-status-of-the-mem-alloc-profiling-before-printing/20250903-000616
> > base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> > patch link: https://lore.kernel.org/r/1491df0ac12a7626b7c9b00e26a6e10adb8c9045.1756827906.git.pyyjason%40gmail.com
> > patch subject: [PATCH v2 2/2] mm/show_mem: Add trylock while printing alloc info
> > config: i386-buildonly-randconfig-001-20250903 (https://download.01.org/0day-ci/archive/20250903/202509031744.HcibSETe-lkp@intel.com/config)
> > compiler: gcc-13 (Debian 13.3.0-16) 13.3.0
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250903/202509031744.HcibSETe-lkp@intel.com/reproduce)
> >
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@...el.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202509031744.HcibSETe-lkp@intel.com/
> >
> > All warnings (new ones prefixed by >>):
> >
> > In file included from mm/show_mem.c:18:
> > mm/show_mem.c: In function 'show_free_areas':
> > mm/show_mem.c:336:49: error: 'NR_ZSPAGES' undeclared (first use in this function); did you mean 'NR_STATS'?
> > 336 | K(zone_page_state(zone, NR_ZSPAGES)),
> > | ^~~~~~~~~~
>
> This is from a different patch and being fixed. Interesting that lkp will
> report additional warnings even in presence of prior errors.
Thanks. Understood.
>
> > mm/internal.h:560:16: note: in definition of macro 'K'
> > 560 | #define K(x) ((x) << (PAGE_SHIFT-10))
> > | ^
> > include/linux/printk.h:512:26: note: in expansion of macro 'printk_index_wrap'
> > 512 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
> > | ^~~~~~~~~~~~~~~~~
> > mm/show_mem.c:298:17: note: in expansion of macro 'printk'
> > 298 | printk(KERN_CONT
> > | ^~~~~~
> > mm/show_mem.c:336:49: note: each undeclared identifier is reported only once for each function it appears in
> > 336 | K(zone_page_state(zone, NR_ZSPAGES)),
> > | ^~~~~~~~~~
> > mm/internal.h:560:16: note: in definition of macro 'K'
> > 560 | #define K(x) ((x) << (PAGE_SHIFT-10))
> > | ^
> > include/linux/printk.h:512:26: note: in expansion of macro 'printk_index_wrap'
> > 512 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
> > | ^~~~~~~~~~~~~~~~~
> > mm/show_mem.c:298:17: note: in expansion of macro 'printk'
> > 298 | printk(KERN_CONT
> > | ^~~~~~
> > In file included from include/linux/spinlock.h:89,
> > from include/linux/wait.h:9,
> > from include/linux/wait_bit.h:8,
> > from include/linux/fs.h:7,
> > from include/linux/highmem.h:5,
> > from include/linux/bvec.h:10,
> > from include/linux/blk_types.h:10,
> > from include/linux/blkdev.h:9,
> > from mm/show_mem.c:8:
> > mm/show_mem.c: In function '__show_mem':
> >>> mm/show_mem.c:399:32: warning: unused variable 'mem_alloc_profiling_spinlock' [-Wunused-variable]
> > 399 | static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
>
> This is the warning
>
> I think you can simply move the definition to the existing #ifdef
> CONFIG_MEM_ALLOC_PROFILING block above the spin_trylock(). The kernel now
> uses a new enough C standard to allow this and not only at the beginning of
> a cuntion. While not encouraged to do that in general, this seems to be a
> valid use case.
>
Let me quickly fix both and push v3
>
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > include/linux/spinlock_types.h:43:44: note: in definition of macro 'DEFINE_SPINLOCK'
> > 43 | #define DEFINE_SPINLOCK(x) spinlock_t x = __SPIN_LOCK_UNLOCKED(x)
> > | ^
> >
> >
> > vim +/mem_alloc_profiling_spinlock +399 mm/show_mem.c
> >
> > 396
> > 397 void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> > 398 {
> > > 399 static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
> >
>
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