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 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/show_mem.c b/mm/show_mem.c
index fd85a028a926..e9701d07549b 100644
--- a/mm/show_mem.c
+++ b/mm/show_mem.c
@@ -421,7 +421,9 @@ 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
-	{
+	static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
+
+	if (spin_trylock(&mem_alloc_profiling_spinlock)) {
 		struct codetag_bytes tags[10];
 		size_t i, nr;
 
@@ -448,6 +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
 }
-- 
2.47.3

On Wed, Sep 03, 2025 at 04:16:14AM -0700, 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: Shakeel Butt <shakeel.butt@linux.dev>

On 3 Sep 2025, at 7:16, 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>
> ---
>  mm/show_mem.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>

Acked-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

On Wed, Sep 3, 2025 at 9:30 AM Zi Yan <ziy@nvidia.com> wrote:
>
> On 3 Sep 2025, at 7:16, 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>
> > ---
> >  mm/show_mem.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
>
> Acked-by: Zi Yan <ziy@nvidia.com>

Acked-by: Suren Baghdasaryan <surenb@google.com>


>
> Best Regards,
> Yan, Zi

On 9/3/25 13:16, 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 | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/show_mem.c b/mm/show_mem.c
> index fd85a028a926..e9701d07549b 100644
> --- a/mm/show_mem.c
> +++ b/mm/show_mem.c
> @@ -421,7 +421,9 @@ 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
> -	{
> +	static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
> +
> +	if (spin_trylock(&mem_alloc_profiling_spinlock)) {
>  		struct codetag_bytes tags[10];
>  		size_t i, nr;
>  
> @@ -448,6 +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 03/09/2025 12:16, 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 | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/show_mem.c b/mm/show_mem.c
> index fd85a028a926..e9701d07549b 100644
> --- a/mm/show_mem.c
> +++ b/mm/show_mem.c
> @@ -421,7 +421,9 @@ 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
> -	{
> +	static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
> +
> +	if (spin_trylock(&mem_alloc_profiling_spinlock)) {
>  		struct codetag_bytes tags[10];
>  		size_t i, nr;
>  
> @@ -448,6 +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
>  }