In production, show_mem() can be called concurrently from two
different entities, for example one from oom_kill_process()
another from __alloc_pages_slowpath from another kthread. This
patch adds a spinlock and invokes trylock before printing out the
kernel alloc info in show_mem(). This way two alloc info won't
interleave with each other, which then makes parsing easier.
Signed-off-by: Yueyang Pan <pyyjason@gmail.com>
---
mm/show_mem.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/show_mem.c b/mm/show_mem.c
index 51892ce2efc4..4c876ea2b66f 100644
--- a/mm/show_mem.c
+++ b/mm/show_mem.c
@@ -396,6 +396,7 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
{
+ static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
unsigned long total = 0, reserved = 0, highmem = 0;
struct zone *zone;
@@ -421,7 +422,7 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
#endif
#ifdef CONFIG_MEM_ALLOC_PROFILING
- {
+ if (spin_trylock(&mem_alloc_profiling_spinlock)) {
struct codetag_bytes tags[10];
size_t i, nr;
@@ -449,6 +450,7 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
ct->lineno, ct->function);
}
}
+ spin_unlock(&mem_alloc_profiling_spinlock);
}
#endif
}
--
2.47.3Hi 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@intel.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)),
| ^~~~~~~~~~
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);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
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);
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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@intel.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.
> 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.
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 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);
>
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@intel.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);
> >
>
On 02/09/2025 16:57, Yueyang Pan wrote:
> In production, show_mem() can be called concurrently from two
> different entities, for example one from oom_kill_process()
> another from __alloc_pages_slowpath from another kthread. This
> patch adds a spinlock and invokes trylock before printing out the
> kernel alloc info in show_mem(). This way two alloc info won't
> interleave with each other, which then makes parsing easier.
>
> Signed-off-by: Yueyang Pan <pyyjason@gmail.com>
Acked-by: Usama Arif <usamaarif642@gmail.com>
> ---
> mm/show_mem.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/show_mem.c b/mm/show_mem.c
> index 51892ce2efc4..4c876ea2b66f 100644
> --- a/mm/show_mem.c
> +++ b/mm/show_mem.c
> @@ -396,6 +396,7 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
>
> void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> {
> + static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
> unsigned long total = 0, reserved = 0, highmem = 0;
> struct zone *zone;
>
> @@ -421,7 +422,7 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
> #endif
> #ifdef CONFIG_MEM_ALLOC_PROFILING
> - {
> + if (spin_trylock(&mem_alloc_profiling_spinlock)) {
> struct codetag_bytes tags[10];
> size_t i, nr;
>
> @@ -449,6 +450,7 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> ct->lineno, ct->function);
> }
> }
> + spin_unlock(&mem_alloc_profiling_spinlock);
> }
> #endif
> }
On 9/2/25 17:57, Yueyang Pan wrote:
> In production, show_mem() can be called concurrently from two
> different entities, for example one from oom_kill_process()
> another from __alloc_pages_slowpath from another kthread. This
> patch adds a spinlock and invokes trylock before printing out the
> kernel alloc info in show_mem(). This way two alloc info won't
> interleave with each other, which then makes parsing easier.
>
> Signed-off-by: Yueyang Pan <pyyjason@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> mm/show_mem.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/show_mem.c b/mm/show_mem.c
> index 51892ce2efc4..4c876ea2b66f 100644
> --- a/mm/show_mem.c
> +++ b/mm/show_mem.c
> @@ -396,6 +396,7 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
>
> void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> {
> + static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
> unsigned long total = 0, reserved = 0, highmem = 0;
> struct zone *zone;
>
> @@ -421,7 +422,7 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
> #endif
> #ifdef CONFIG_MEM_ALLOC_PROFILING
> - {
> + if (spin_trylock(&mem_alloc_profiling_spinlock)) {
> struct codetag_bytes tags[10];
> size_t i, nr;
>
> @@ -449,6 +450,7 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> ct->lineno, ct->function);
> }
> }
> + spin_unlock(&mem_alloc_profiling_spinlock);
> }
> #endif
> }
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